U.S. patent application number 09/906933 was filed with the patent office on 2002-01-24 for sprayable phosphate cementitious coatings and a method and apparatus for the production thereof.
Invention is credited to Goodson, David M..
Application Number | 20020009622 09/906933 |
Document ID | / |
Family ID | 32912925 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020009622 |
Kind Code |
A1 |
Goodson, David M. |
January 24, 2002 |
Sprayable phosphate cementitious coatings and a method and
apparatus for the production thereof
Abstract
A sprayed-on phosphate cement coating formed from the
combination and reaction of a phosphoric acid solution and a base
metal solution. The acid solution and base solution may be
intermixed prior to spraying, during spraying, or on a substrate.
The curing reaction rate of the phosphate cement coating and its
final physical properties may be controlled by adding various
retardants, accelerants, reducers, wetting agents,
superplasticizers, buffers, water reducers, adhesive agents,
hardening agents, and/or sequestrants to the precursor solutions.
The curing rate and properties of the cement coating may be further
controlled by adjusting the temperature of the precursor solutions
and/or the target substrate.
Inventors: |
Goodson, David M.;
(Hinsdale, IL) |
Correspondence
Address: |
C. John Brannon
Woodard, Emhardt, Naughton, Moriarty and McNett
Bank One Center/Tower, Suite 3700
111 Monument Circle
Indianapolis
IN
46204-5137
US
|
Family ID: |
32912925 |
Appl. No.: |
09/906933 |
Filed: |
July 17, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09906933 |
Jul 17, 2001 |
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09631445 |
Aug 2, 2000 |
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60146912 |
Aug 3, 1999 |
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Current U.S.
Class: |
428/703 ;
428/689; 428/704 |
Current CPC
Class: |
Y02W 30/92 20150501;
C04B 41/70 20130101; B32B 13/00 20130101; C04B 41/67 20130101; C04B
28/34 20130101; C04B 2111/72 20130101; C04B 2111/00577 20130101;
Y02W 30/91 20150501; C04B 41/52 20130101; Y02W 30/94 20150501; C04B
41/5092 20130101; C04B 41/009 20130101; C09D 7/00 20130101; C04B
2111/00637 20130101; C04B 28/34 20130101; C04B 14/045 20130101;
C04B 14/06 20130101; C04B 14/062 20130101; C04B 14/304 20130101;
C04B 18/08 20130101; C04B 18/146 20130101; C04B 28/34 20130101;
C04B 14/045 20130101; C04B 14/06 20130101; C04B 14/062 20130101;
C04B 14/26 20130101; C04B 18/08 20130101; C04B 18/146 20130101;
C04B 28/34 20130101; C04B 14/045 20130101; C04B 14/06 20130101;
C04B 14/062 20130101; C04B 18/08 20130101; C04B 18/101 20130101;
C04B 18/146 20130101; C04B 28/34 20130101; C04B 22/00 20130101;
C04B 24/00 20130101; C04B 40/0641 20130101; C04B 41/5092 20130101;
C04B 41/455 20130101; C04B 41/009 20130101; C04B 28/34 20130101;
C04B 41/009 20130101; C04B 28/04 20130101 |
Class at
Publication: |
428/703 ;
428/704; 428/689 |
International
Class: |
B32B 013/00 |
Claims
I claim:
1. A sprayed-on phosphate cement coating on a surface, the
phosphate cement coating produced through a process comprising the
steps of: a) providing a first cementitious constituent; b)
providing a second cementitious constituent adapted to combine with
the first cementitious constituent to produce a phosphate cement
coating; c) spraying the surface with the first cementitious
constituent; d) spraying the surface with the second cementitious
constituent; and e) reacting the first and second cementitious
constituents to produce a phosphate cement coating.
2. The coating of claim 1 wherein the first constituent is a
phosphoric acid and the second constituent is a metallic base.
3. The coating of claim 2 wherein the first constituent includes at
least one of the following group: potassium phosphate, calcium
phosphate, magnesium phosphate, sodium phosphate, aluminum
phosphate, zinc phosphate; and wherein the second constituent
includes at least one of the following group: magnesium oxide,
magnesium hydroxide, calcium hydroxide, zirconium oxide, zirconium
hydroxide, potassium hydroxide, sodium hydroxide, dolomite, zinc
oxide, aluminum oxide, potash, calcium oxide, lithium carbonate,
barium carbonate, molybdenum oxide, calcium hydroxide, aluminum
hydroxide, tin oxide, tin, nickel oxide, magnesium hydroxide, iron
oxide, titanium oxide, or wood ash.
4. The coating of claim 1 wherein the first constituent is a
metallic base and the second constituent is a phosphoric acid.
5. The coating of claim 4 wherein the first constituent includes at
least one of the following group: magnesium oxide, calcium oxide,
magnesium hydroxide, calcium hydroxide, zirconium oxide, zirconium
hydroxide, potassium hydroxide, sodium hydroxide, dolomite, zinc
oxide, aluminum oxide, iron oxide, titanium oxide, wood ash; and
wherein the second constituent includes at least one of the
following: potassium phosphate, magnesium phosphate, zinc
phosphate, ammonium phosphate, sodium phosphate, calcium phosphate,
iron phosphate.
6. The coating of claim 1 further comprising the step of; g) after
step c) and before step d), adding at least one of the following to
the first constituent: a retardant, an accelerant, a reducer, a
wetting agent, a superplasticizer, a buffer, a water reducer, an
adhesive agent, an air entraining agent, a hardening agent, a
toughening agent, a smoothening agent and a sequestrant.
7. The coating of claim 6: wherein the retardant comprises at least
one of the following: ammonium nitrate, citric acid, acetic acid,
boric acid, fine rice husk ash, chilled water, tri-sodium
phosphate, colostrum, distilled water, deionized water, calcium
citrate, calcium fluoride, sodium fluoride, tartaric acid,
bentonite, diatomaceous earth, sodium carboxy-methycellulose,
cellulose, and guar; wherein the accelerant comprises at least one
of the following: nitric acid, sodium chloride, calcium chloride,
tin, tin oxide, calcium carbonate, potassium carbonate, carbonated
water, hydrogen peroxide, potassium permanganate, sodium
permanganate, sodium silicate, potassium silicate, sodium
aluminate, aluminum hydroxide, fly ash, wollastonite, sodium
hypochlorite, sodium chloride, potassium chloride, volcanic ash,
distilled petroleum, and heated water; wherein the adhesive agent
comprises at least one of the following: sodium phosphate, fly ash,
and aluminum phosphate; wherein the hardening agent comprises at
least one of the following: calcium fluorosilicate, sodium
fluorosilicate, magnesium fluorosilicate, silicon carbide, boron
nitride, tungsten carbide, molybdenum, molybdenum oxide, nickel
oxide, chromium oxide, mullite, kyanite, alumina, ammonium
meta-vanadate, ferrovanadium, vanadium oxide, aluminum, diamond,
magnesium phosphate, sodium phosphate, zinc phosphate, colostrum,
sodium silicate, potassium silicate, fly ash, zirconium hydroxide,
zirconium oxide, zirconium silicate, zirconium stearate, silica
fume, calcium silicate, titanium dioxide, cordierite, and aluminum
phosphate; wherein the smoothening agent comprises at least one of
the following: fumed silica, colloidal silica, silica flour,
Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, kaolin, smectite, hectorite,
potassium phosphate, potassium oxide, potassium hydroxide, and
nitro cellulose, potassium peroxymonosulfate, sodium persulfate,
sodium hypochlorite, Al2O3; and wherein the toughening agent
comprises at least one of the following: polyvinyl acetate and
ground hard rubber.
8. The coating of claim 1, further comprising the step of: h) after
step c) and before step d) adding a polymerizing agent to the first
constituent.
9. The coating of claim 8, further comprising the step of: i) after
step c) and before step d) adding a polymer initiator to the second
constituent.
10. The coating of claim 1 wherein the surface is heated.
11. The coating of claim 1 wherein the surface is cooled.
12. The coating of claim 1 wherein the steps d) and e) occur
substantially simultaneously and wherein the first and second
constituents intermix during spraying.
13. The coating of claim 1 further comprising the step: after step
c) and before step d) mixing the first and the second constituents;
wherein steps d) and e) occur substantially simultaneously.
14. The coating of claim 1 wherein at least one of the constituents
is heated.
15. The coating of claim 1 wherein at least one of the constituents
is cooled.
16. The coating of claim 1 further comprising the step: adding a
colorant to the first constituent.
17. A phosphate cement coating for a substrate produced by the
following method: aa) providing a first phosphoric acid liquid
component; bb) providing a second metallic base liquid component
adapted to reactively combine with the first phosphoric acid liquid
component to produce a phosphate cement coating; cc) providing a
cooling agent; dd) spraying the substrate with the first phosphoric
acid liquid component; ee) spraying the substrate with the second
metallic base liquid component; ff) spraying the substrate with the
cooling agent; gg) mixing the first phosphoric acid liquid
component, the second metallic base liquid component and the
cooling agent to form a phosphate cement coating; and hh) curing
the phosphate cement coating.
18. The phosphate cement coating of claim 17 wherein the mixing of
the first phosphoric acid liquid component, the second metallic
base liquid component and the cooling agent occurs on the
substrate.
19. The phosphate cement coating of claim 17 wherein the mixing of
the first phosphoric acid liquid component, the second metallic
base liquid component and the cooling agent occurs during
spraying.
20. The phosphate cement coating of claim 17 wherein the mixing of
the first phosphoric acid liquid component, the second metallic
base liquid component and the cooling agent occurs in a liquid
paint medium.
21. The phosphate cement coating of claim 17 wherein the cooling
agent comprises at least one of the following: ammonium nitrate,
chilled water, and water ice.
22. The phosphate cement coating of claim 17 wherein the substrate
is a first layer of Portland cement and further including a second
layer of Portland cement bondingly coating the phosphate cement
coating.
23. A phosphate cement, comprising: a substrate; a phosphoric acid
portion; a metallic base portion; and a reaction-temperature
controlling means; wherein the phosphoric acid portion and the
metallic base portion are applied to the substrate; and wherein the
phosphoric acid portion and the metallic base portion are reacted
to form a phosphate cement material.
24. The phosphate cement of claim 23 wherein the phosphoric acid
portion and the metallic base portion are intermixed prior to
application to the substrate.
25. The phosphate cement of claim 23 wherein the phosphoric acid
portion and the metallic base portion are sprayed onto the
substrate and wherein the phosphoric acid portion and the metallic
base portion are intermixed during spraying.
26. The phosphate cement of claim 23 wherein the phosphoric acid
portion and the metallic base portion are intermixed on the
substrate.
27. The phosphate cement of claim 23 wherein the phosphoric acid
portion and the metallic base portion are intermixed in a liquid
paint.
28. The phosphate cement of claim 23 wherein the reaction
temperature controlling means is an additive added to a portion
prior to application to the substrate.
29. The phosphate cement of claim 28 wherein the additive comprises
at least on of the following: ammonium nitrate, citric acid, acetic
acid, boric acid, fine rice husk ash, chilled water, tri-sodium
phosphate, colostrum, distilled water, deionized water, calcium
citrate, calcium fluoride, sodium fluoride, tartaric acid,
bentonite, diatomaceous earth, sodium carboxy-methycellulose,
cellulose, guar, nitric acid, sodium chloride, calcium chloride,
tin, tin oxide, calcium carbonate, sodium carbonate, potassium
carbonate, carbonated water, hydrogen peroxide, potassium
permanganate, sodium permanganate, sodium silicate, potassium
silicate, sodium aluminate, aluminum hydroxide, fly ash,
wollastonite, distilled petroleum, and heated water.
30. A method of toughening paint, comprising the steps of: a)
dissolving a phosphate source in the paint; b) applying the paint
to a surface; and c) reacting the phosphate with a anions present
in the paint to form a dispersed phosphate cement phase in the
paint.
31. The method of claim 30 wherein the phosphate source includes at
least one of the following group: potassium phosphate, calcium
phosphate, magnesium phosphate, sodium phosphate, aluminum
phosphate, and zinc phosphate.
32. The method of claim 31 wherein the phosphate source also
includes silica.
33. The method of claim 31 wherein the paint includes at least one
of the following: an oxide of a cation chosen from the group
including Ca, Mg, Zn, Ti, K, Zr, Co, Al, Ni, MO, Cr and V, a
hydroxide of a cation chosen from the group including Ca, Mg, Zn,
Ti, K, Na, Zr, Co, Ni, Al, Ni and Cr; a carbonate of a cation
chosen from the group including Ca, Mg, Co, Ba, Li and K; barium
titanate; boric acid; tartric acid; acetic acid; citric acid;
oxalic acid; and a nitrate of a cation chosen from the group
including Na, K, and Ca.
34. A method of tuckpointing a substrate with phosphate cement
slurry, comprising the steps of: a) imparting an electrical charge
to the substrate; b) imparting an opposite electrical charge to the
phosphate cement slurry; and c) applying the phosphate cement
slurry to the substrate.
35. The method of claim 32 wherein the phosphate cement slurry
contains ferromagnetic particles.
36. The method of claim 32 wherein step a) includes applying a
charged solution to the substrate.
37. The method of claim 32 further comprising before step b),
precoating the substrate with an alkali coating.
38. The method of claim 35 wherein the alkali coating is an aqueous
solution including at least one of the following in solution: NaOH,
KOH, caustic soda, and soda ash.
39. A method of forming a laminate, comprising the steps of: a)
forming a first non-phosphate cement layer; b) depositing a second,
phosphate cement layer over the first non-phosphate cement layer;
c) depositing a third non-phosphate cement layer over the phosphate
cement layer.
40. The method of claim 39, wherein the first non-phosphate cement
layer is Portland cement and the third non-phosphate cement layer
is Portland cement.
41. The method of claim 39 wherein the first non-phosphate cement
layer is Portland cement and the third non-phosphate cement layer
is asphalt.
42. The method of claim 39 wherein the first non-phosphate cement
layer is asphalt and the third non-phosphate cement layer is
Portland cement.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 09/631,445 filed Aug. 2, 2000 and claims
priority to U.S. Provisional Application Serial No. 60/146,912
filed Aug. 3, 1999.
TECHNICAL FIELD OF THE INVENTION
[0002] The present invention relates generally to ceramic materials
and, more particularly, to sprayable phosphate cement coatings and
a novel method and apparatus for producing them.
BACKGROUND OF THE INVENTION
[0003] Ceramic cements are mixtures of water and reactive metal
oxides that harden and fasten upon setting. Cements have a variety
of familiar uses, such as the adhesive component to concrete
(essentially an agglomeration of rocks held together by cement),
the bonding layer that holds bricks together to form walls, as
structural building materials such as patio or garage slabs. The
cement of choice for most of these familiar uses is Portland
cement, a mixture of water and calcined lime and silica. Upon
curing, the primary constituents of Portland cement are dicalcium
silicate and tri-calcium silicate phases. Portland cement has the
advantage of being cheap to produce and relatively easy to mix and
pour. Part of the reason Portland cement is so cheap is because the
silica component may come from a wide variety of sources, usually
silica-containing clays, and also because these clays do not have
to be especially pure or consistent.
[0004] Portland cement also suffers from some disadvantages,
inconsistency of physical properties arising from the inherent
inconsistency of the source materials (both in composition and
quality) being chief among them. Portland cements also have the
disadvantage of having a relatively high viscosity. While they are
well adapted to pouring and spreading, Portland cements are not
well suited for pumping and spraying. Moreover, Portland cements
are characterized by a relatively slow curing time. Another
disadvantage of Portland cement is that it does not bond well to
itself, especially if the existing cement surface is already
hardened. Portland cement-containing structures, such as cement
driveways or road segments, must be formed in essentially one step.
If there is an interruption in the forming of a Portland cement
body sufficient to allow the cement to begin to cure, a structural
discontinuity or "cold joint" can result. Moreover, Portland cement
cannot be used to patch a Portland cement structure absent costly
and time consuming surface pre-treatment at the patch interface,
for example sawing out the old rebar and damaged concrete, drilling
holes for new rebar, placing the new rebar in the holes, and
pouring and finishing the new concrete.
[0005] While Portland cement is usually applied by pouring from a
mixer and Portland cement mortar is spread from a palette, Portland
cement can also be sprayed. Sprayed Portland cement, or
"shotcrete", is applied as a thick, rough layer of cement only in
industrial applications that do not necessitate even or controlled
coating, such as "shotcreting" over wire mesh for producing the
foundations of swimming pools and for walls of tunnels and mines.
Shotcrete is applied in very thick rough coats through enormous and
expensive pneumatic sprayers and pumps that are not suited for
smaller scale applications. Shotcrete sprayers cannot produce thin
coatings or smooth finishes, and shotcreted surfaces sacrifice
aesthetics for functionality. Often, half of the shotcreted
Portland cement is lost to "rebound". The rebounded Portland cement
becomes widely scattered, cannot be reused, and contributes to
waste products that require time and effort to clean up. Portland
cements set up and harden very slowly and are fairly porous,
especially to road salt, which can degrade and rust steel
reinforcement members in the concrete, causing expansion of the
reinforcement members and the eventual rupture of the cement from
within.
[0006] Another kind of cement is phosphate cement. Phosphate
cements undergo an acid-base reaction during curing. Typically, the
acid component is either phosphoric acid (usually in liquid form)
or an alkali-earth phosphate salt such as magnesium phosphate,
calcium phosphate or ammonium phosphate. The base component is
typically highly calcined magnesium oxide, one supplier of which is
Martin Marietta Magnesia Specialties of Baltimore, Md. The
compositions of the acid and base pair are chosen such that the
resulting combination will react to form a cementitious
metal-phosphate. The acid and base components when mixed rapidly
cure to form a cementitious metal phosphate phase. The phosphate
cement forms by a highly exothermic reaction and sets up rapidly,
quickly agglomerating and increasing in viscosity.
[0007] Most phosphate cements have excellent strength and hardness
characteristics, and have the additional advantage of adhering to
most other materials, including cement (both phosphate and
Portland), brick, metal, wood, most wood products, insulation,
asphalt, roofing materials, membranes and some glasses. Phosphate
cements also have excellent chemical stability and compressive
strength, and have toughness characteristics superior to those of
Portland cement. Moreover, phosphate cements tend to set up with
little or no open porosity and therefore can be used to form
waterproof forms and seals. Phosphate cements, like most ceranucs,
are fireproof and resistance to very high and tend to be
electrically nonconductive and are good thermal and acoustic
insulators.
[0008] Traditionally, phosphate cements have been used almost
exclusively for dental and biological applications, road patching,
and specialized refractory applications. This is because phosphate
cements are roughly an order of magnitude more expensive than
Portland cement and cannot be used in bulk because the highly
exothermic nature of the phosphate reaction causes phosphate
cements to set up rapidly and to agglomerate, while generating a
lot of heat. Unlike in Portland cement, where the heat of hydration
evolves slowly and plateaus, the heat of hydration of phosphate
cements spikes quickly, with great heat evolution occurring
promptly after the cement is mixed. This results in the phosphate
cement setting up too quickly (and exothermically generating too
much heat) to be workable for anything except road patching, thus
rendering phosphate cement undesirable for mass pours.
[0009] There are a variety of coating applications (fireproofing,
water and fluid sealants, electrical insulation foam, electrical
insulation coatings, thermal insulation coatings, chemical
insulation coatings, rust proofing, overcoating existing roofs,
walls, drywall, siding, floors, basements, roads and the like) that
could be addressed by a thin or thick ceramic coating of a material
having the properties of phosphate cement, but currently the
technology does not exist to commercially apply thin cement
coatings and, more particularly, to spray phosphate cements
coatings. While the superior properties of phosphate cements would
make them desirable for a much wider range of applications, their
reactivity makes them ill-suited for bulk mixing, dipping,
brushing, rolling and spraying since they tend to thicken and
agglomerate quickly, rapidly clogging and packing spray nozzles,
needle valves, hoses, and containers. This makes phosphate cements
impractical for spraying, especially since most commercial spray
apparati have orifices and conduits too small to accommodate the
flow of a liquid having the density and viscosity of a phosphate
cement. Further, most commercial spray apparati are expensive, and
would be ruined by phosphate cements (especially those containing
aggregates) setting up in the sprayer hoses, nozzles, and
containers, thus making their usage with phosphate cements
impractical. Moreover, since ejecting the phosphate cement is the
primary method of dissipating the excess waste heat generated by
the acid-base reaction, a clogged spray line or nozzle can
contribute to the overheating of the sprayer system, therefore
increasing the hazard of fire or an explosion of the closed
container. Further, overheating of the cement mixture in the
sprayer also increases the reaction rate, thereby evolving even
more heat and potentially causing further agglomeration in the
spray gun and hoses resulting in a catastrophic runaway
reaction.
[0010] There are currently no known mineral cements capable of
being applied as a thin, sprayed on coating or layer. There are
also currently no known phosphate cement compositions that may be
applied to a substrate by conventional spraying, coating, dipping
or brushing techniques. There is therefore a need for a phosphate
cement material with a controllably slow reaction and curing rate
that can be mixed in bulk with a stable, low viscosity suitable for
application as a thin coating via sprayer or via conventional
application techniques. The present invention addresses this
need.
SUMMARY OF THE INVENTION
[0011] One form of the present invention relates to a phosphate
cement composition with a sufficiently controlled reaction rate
that the phosphate cement may be mixed in bulk and with suitable
viscosity to be sprayed or used for mass pours. Another form of the
present invention relates to a method and apparatus for mixing and
spray applying a phosphate cement composition.
[0012] One object of the present invention is to provide an
improved cement. Related objects and advantages will be apparent
from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a perspective view of a commercial embodiment of a
prior art spray gun apparatus.
[0014] FIG. 2 is a first perspective view of four different
phosphate cement spray coatings on a concrete floor.
[0015] FIG. 3 is an enlarged perspective view of two of the
phosphate coatings of FIG. 2.
[0016] FIG. 4 is a perspective view of a sprayed-on phosphate
cement coating partially covering a brick and mortar wall.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiment illustrated in the drawings and specific language will
be used to describe the same. It will nevertheless be understood
that no limitation of the scope of the invention is thereby
intended, such alterations and further modifications in the
illustrated device, and such further applications of the principles
of the invention as illustrated therein being contemplated as would
normally occur to one skilled in the art to which the invention
relates.
[0018] General Composition and Criteria for Maintaining
Sprayability
[0019] The present invention relates to a sprayable phosphate
cement material with a controlled curing reaction time and
viscosity. The cement composition includes a phosphoric acid
component, a metallic alkali or base component, and water. The
phosphoric acid component and the metallic base component are mixed
with water separately to form component slurries (i.e., an acid
slurry and a base slurry), and each slurry is maintained separately
until the application step. The application step preferentially
involves first coating a desired surface with the phosphoric acid
mixture and then with the metallic base slurry. Alternately, the
application step may involve first coating the desired surface with
the base slurry and then the phosphoric acid solution, or
simultaneously spraying the desired surface with the both the
phosphoric acid solution and the base slurry from separate sources,
wherein the acid and base components mix in transit or in situ on
the desired surface.
[0020] Preferentially water, metallic base and one or more
retardants, emulsifiers, deflocculents, sequestrants and/or
dispersants are added to cold water and mixed in with the silica
source(s) and other aggregates and fillers and colorants to form a
slurry. Next, the liquid phosphoric acid or phosphate salts are
quickly mixed into the slurry, and the slurry is then preferably
immediately sprayed onto a desired target, although the use of cold
precursors and strong retarders can extend the shelf-life, pot life
and working time of the mixed phosphate cement slurry such that
immediate spraying is not a requirement. Alternately, with the use
of strong retardant additives, dry powder phosphate salts, silica
sources, and metallic oxide alkali powders can be mixed together to
form a slurry having a long enough pot-life to make spraying
possible.
[0021] After the phosphoric acid and/or the phosphoric salt(s) and
the metallic base components are mixed, the phosphate cement slurry
is preferably used promptly. The individual cement components may
be mixed in spray cans or any clean containers and mixed right on
the job, preferably in a cool environment. Preferably, the water
used in the mixture is added cold in order to retard the
progression of the exothermic acid-base phosphate cement-forming
reaction.
[0022] Alternately, the phosphoric acid and/or the base coat may be
brushed, troweled or squeeged on, with the other coat also either
sprayed or brushed or troweled or squeeged on. One coat of the
slurry with acid and base and silica sources is usually enough to
provide good coverage, although subsequent coats are easy to apply
and may be applied immediately after the first coat is applied.
This material may also be rolled on.
[0023] In the preferred embodiment, the waterborne base coating is
applied first. More preferably, the second, phosphoric acid coat
contains a silica source admixed therein.
[0024] Alternatively, the base coating is applied secondly,
preferably by spraying, such that it penetrates the existing
phosphoric acid layer and allows the cementitious reaction to
begin. The silica source, aggregates, flyash and fillers may be
contained in either the first coat, second coat, or both. It should
be noted that spraying is also a densifying technique, since during
spraying much of the water is rebounded or misted out of the
composite.
[0025] The reaction progresses rapidly since the reactants are
spread as a thin coating over a large surface area with a brush,
spray gun, caulking gun, roller, trowel or squeegee. Also, the heat
generated by the reaction is dissipated quickly, again because the
reaction occurs over a large area and is generated in a thinly
spread film having a very high surface area to volume ratio. In one
alternate embodiment, the base coat is applied first, followed by
the phosphoric acid coat, thereby catalyzing the in-place base
slurry.
[0026] Some preferred phosphoric acid components include calcium
phosphate, potassium phosphate, magnesium phosphate, sodium
phosphate, aluminum phosphate, ammonium phosphate, zinc phosphate
and combinations thereof. By using controlled combinations of
different phosphate salts, each one spiking in temperature at a
different time, the overall temperature profile of the composition
is controlled so as to substantially minimize the maximum
temperature reached. Therefore, the controlled combination of the
above-listed phosphate salts has the same effect as the addition of
a temperature retarder, especially when the sizes of the phosphate
salt precursors are varied and also when the sizes of the oxides
are varied, as well as replacing in whole or in part the oxides
and/or acid salts with slower reacting acids and bases and/or
oxides of lower valences. For example, the reaction may be retarded
by replacing about 1-80% of the calcined MgO with Fe.sub.2O.sub.3,
KOH, Al.sub.2O.sub.3, calcined mullite, kyanite or zirconium
oxides. Likewise, adding in or replacing some or all of the fast
reacting ammonium, calcium, or magnesium phosphate salts with less
active MKP (mono potassium phosphates) or polyphosphates or with
di-potassium phosphate, di-calcium phosphate, di-ammonium phosphate
and/or other alkali earth phosphates with higher pH values than MCP
(mono calcium phosphate) or MKP or MAP (mono ammonium phosphate) or
MMP (mono magnesium oxide), also phosphorous acid in whole or as a
partial replacement for phosphoric acid or phosphate salts. In
addition, the resultant mix of different shaped and size crystals
can yield denser packing and gives a "granite effect" to a
composition formed therefrom, whereby the composition has improved
fracture strength as cracks cannot as easily propagate through a
composition with no common cleavage lines.
[0027] The phosphoric acid component may be either a solid
(preferably a powder) or a liquid. Some preferred metallic base
components include magnesium oxide, dolomite, zinc oxide, aluminum
oxide, calcium oxide, lithium carbonate, barium carbonate, barium
sulfate, molybdenum oxide, calcium hydroxide, aluminum hydroxide,
tin oxide, nickel oxide, nickel hydroxide, cobalt oxide, cobalt
hydroxide, vanadium oxide, magnesium hydroxide, iron oxide,
titanium oxide, chromium oxide, chromium hydroxide, dolomite,
manganese oxide, zirconium oxide, zirconium hydroxide, NaOH, KOH,
sodium carbonate, potassium carbonate, calcium feldspar, sodium
feldspar, potassium feldspar, potash, caustic potash, lime,
dolomitic lime, hydrated lime, finishing lime, air entrained lime,
air entrained dolomitic lime, mason's lime, EZ Spread (available
from Rockwell Lime Company, Manitowoc, Wis.) and wood ash.
[0028] One means of controlling the reaction rate of the cement is
by controlling the temperatures of the cement components. The
colder one or both of the components are kept, the slower the
reaction progresses. One way of controlling the temperature of the
phosphoric acid component and the metallic base component is by
cooling the water used in the admixture of each. Another means of
temperature control is cooling one or both of the components'
containers and/or the spraying apparatus, such is in an ice bath,
by refrigeration or with dry ice. Another means of controlling the
reaction rate is to keep the surface to be sprayed cold, such as
with ice or cold water or dry ice. Various combinations of these
cooling techniques may be employed to obtain maximum temperature
control of the reaction.
[0029] The following cooling additives may be added to the
phosphate cements to reduce the reaction temperature thereof:
ammonium nitrate (preferably added either as a powder or in aqueous
solution) or any other like chemical that reacts endothermically.
Such additives allow the mass pouring of phosphate cement with less
heat shrinkage, even in hot weather. Likewise, using potassium
metal oxide ions, potassium hydroxide and/or potassium oxide or
feldspars in lieu of ammonium or magnesium phosphate salts or
phosphoric acid also reduces the heat of reaction. Similarly, the
reaction heat may be reduced through the novel use of phosphorous
acid in lieu of the phosphate salts of ammonia or magnesium or
phosphoric acid. Cooling the phosphate cement reaction retards
initial and final set and lowers the overall heat generation,
reducing shrinkage and allowing more work time and pot life. Heat
shrinkage in both phosphate and Portland cements is also
significantly reduced by addition of CMC's, cellulosic materials,
guar, aloe vera, saw dust, Berylex.TM. (made by Chemstone Products
of San Jose, Calif.) and the like.
[0030] Another means of controlling the reaction rate is the use of
the retarders (surfactants, retarders, dispersants, water reducers,
super plasticizers, barium sulfate, air entrainers (such as
Silipon.TM. and Desinate.TM. by Hercules of Wilmington Del.),
cellulose, cmc's and sequestrants) in the cement-forming
components. Preferably, the retarders are added to the water before
it is added to the powdered phosphoric acid solution and/or the
metallic base precursors (minerals, metal oxides, and the like) to
form the base slurry. This approach provides that no water contacts
the component materials (usually powders) without a
dispersant/retarder present. Since cement-forming powders are
reactive, the retarders slow the setting time by keeping them
apart, eliminating or reducing rapid agglomeration and aiding to
control the reaction of the cement. Alternately, the cementitious
precursors and retarders may be prepared as a single dry mixture
ready to use with the addition of water.
[0031] Another embodiment of the present invention contemplates
pre-mixing the phosphoric acid solution and the metallic base
slurry before spraying. In this embodiment, it becomes necessary to
reduce the reaction rate of the cement sufficiently to keep the
mixed cement slurry from becoming too viscous to remain sprayable
as a thin coating. This is achieved through cooling the mixed
solution, by using chilled water and/or refrigeration of the
container and sprayer and/or through the use of retarders. As
above, retarders are used to keep the component particles dispersed
in order to slow the chemical reaction and prevent agglomerations
from forming inside the sprayer. Additionally, either or both the
acid and base components may be saturated in carriers such as
sawdust, cellulose, cmc's, guar and the like to provide a mechanism
through which they may slowly and controlledly enter the slurry.
Another method for retarding curing is to put the slurry into the
mixing vessel, spray gun, pump, or pressure pot and keeping it
agitated, as these slurries tend to be thixotropic and agitation
retards curing. Still another method of controlling the speed of
the phosphate cement-forming reaction is through the use of pH
buffers to regulate the pH of the solution and thereby its reaction
rate. Yet another means of regulating the reaction rate is by
controlling the concentration of the acid and base components or,
conversely, the water component. Increasing the water concentration
will slow the reaction rate of the cement. Traditionally phosphate
cement manufacturers want a low water/cement ratio, as they believe
that like Portland cement, the lower the w/c ratio the greater the
compressive strength. Through the addition of more mix water, the
crystals continue to grow/form as long as there is unreacted acid
and base present, the extra water facilitating exchange of
unreacted acid and base ions for continued hardening and pore
filling. By keeping the size of the reactive particles small (such
as by choosing to include fly ash and miconized silica) the
reaction may be coaxed to nearly theoretical completion in
reasonably short times. Small particle sizes also facilitates
achieving nearly theoretical density through the filling of pores,
which contributes to increased tensile, elastic, ductile, shear and
compressive strengths.
[0032] It is preferred that the phosphate cement be mixed
thoroughly. If an even stronger and less porous cement is desired,
it is more preferred that a plastic resin and/or catalyst/initiator
be admixed therein to yield a strong phosphate cement that is less
porous and more water resistant. The additions of MMA (methyl
methacrylate), EMA (ethyl methacrylate), BMA (butyl methyl
methacrylate) and other epoxies, urethanes and plastics (especially
moisture-cured plastics) can also yield harder or tougher cements.
Moreover, the addition of an emulsifier helps to better disperse
the above additives in the cementitious mixture, as do some water
reducers (such as Darvon 2 from R. T. Vanderbilt of Norwalk,
Conn.). Darvon 2 is especially attractive for this use, since it
also acts as a dispersant and an emulsifier. Phosphate cements cure
exothermically, generating substantial amounts of heat quickly. The
heat generated by the curing phosphate cement likewise speeds the
curing of endothermic plastics and plastic coatings, such as bunary
epoxies, polyurethanes and moisture-cure resins. Additionally, the
heat generated by the curing phosphate cements is often sufficient
to raise the energy of a system containing an exothermically curing
component enough to initiate the reaction (in other words, if the
system includes a component that requires a predetermined energy
influx in order to begin reacting, the heat spike produced by the
curing phosphate cement usually exceeds the predetermined energy
influx requirement). These phosphate cements are compatible with
numerous catalysts, such as BPO, and will even mix with Bondo.TM.
(available from Dynatron/Bondo Corp. of Atlanta, Ga.).
[0033] It is preferred that the sprayed surface first be cleaned in
order to optimize the bonding of the reactive phosphate cement. It
is not necessary to abrade or acid etch a surface in preparation
for cement spraying, although a wash with phosphoric acid (or other
acids such as TSP=tri sodium phosphate) or NaOH or KOH solutions
does tend to enhance bonding. Attaching an electrical charge to the
substrate or the substrate wetting solution along with an opposite
charge imparted on the slurry being applied increases adhesion.
Including a magnetic ingredient, such as iron oxide or the like,
into the wetting solution on the substrate and/or into the slurry
to be applied can also increase adhesion. This is useful for tuck
pointing, in that is greatly reduces the labor in an otherwise
labor intensive process, and makes it possible to use power mortar
guns or caulking guns, instead of placing all mortar with very
small hand trowels from small handheld palettes. Other cementitious
or plastic based products for overlaying concrete require that the
concrete surface first be cleaned and then either etched or
abraded.
[0034] A smooth surface finish may be produced by limiting the size
and/or amount of the aggregate component of the cement. Also, the
additions of diatomaceous earth and/or bentonite, Laponite.TM.
(available from Southern Clay Products, Inc., Gonzales, Tex.),
hectorites, smectites, montmorillonite, MetaMax.TM. (available from
the Engelhard Corporation of Iselin, N.J.), air entrainers,
defoamers, cmc's, ethyl methyl celluloses, ethyl hydroxyethyl
celluloses, potash, feldspars, small micron or nanosized particles
of ingredients, smaller less reactive aggregates, lower valence
oxides. Barium sulphate, CMC's, ethyl hydroxyethyl cellulose,
cellulose ethers, cellulose, methyl propyl cellulose, Culminol.TM.
and Nexton.TM. (made by Hercules Incorporated's Aqualon Division in
Wilmington, Del.), Bermocoll.TM. (available from Akzo-Nobel,
Sweden), sodium silicate, potassium silicate, fumed silica,
colloidal silica, silica flour or the like may improve the surface
finish without substantially diminishing the cement's strength or
chemical stability. The aforementioned clays and diatomaceous earth
and combinations thereof and barium sulfate retard the initial
setting or curing of the phosphate cement, as well as enhancing the
flowability and workability of the cement (i.e., producing a cement
that is self-leveling and self-consolidating). Diatomaceous earth
and/or bentonite additions (preferably at levels of about 0.1 to
4%) may be thoroughly mixed into the cement precursor to achieve
the result of reducing the number and size of surface pores. Gums,
air entrainers, clays, round aggregate, small aggregate, super
plasticizers, wetting agents, Kelco-Crete.TM. (available from
Astaris LLC of St. Louis Mo.), Berylex.TM., guar, and the treated
cellulosic materials named herein such as cmc's are rheology
modifiers and assist in reducing sag, and making portland and
phosphate cements self-leveling and self-consolidating. Likewise,
the surface finish may be controlled by the additions of
dispersants and/or sequestrants that control the distribution of
the aggregates in the mix. Pre-coating the acid and base and
reactive aggregates with water reducers and/or slow dissolving
non-reactant coatings and/or mixing either the base or acid portion
in last, tend to reduce agglomeration, increase pot life and
initial set times.
[0035] Some Preferred Phosphate Cement Compositions
[0036] In one preferred embodiment, the phosphate cement
composition is comprised of a non-aqueous portion and an aqueous
portion. The non-aqueous portion comprises about 85% silica or
other aggregate and about 15% cement paste (by wt.); wherein the
cement paste consists of an acid component, a base component, and
additives (mostly dispersants and retarders). One preferred
retarder additive is the commercial preparation Dequest 2000.TM. (a
dispersant and sequestrant in one). The base component includes
calcined MgO, and the acid component includes equal amounts of mono
potassium phosphate (MKP) and mono magnesium phosphate (MMP) and
mono calcium phosphate (MCP) or tri-calcium phosphate (TCP) salts.
The aqueous portion is at least about 20% by weight of the cement
paste. The silica/aggregate component is preferably about 13%
silica flour, abut 80% class "C" or class "F" fly ash or micron or
sub-micron sized silicas, about 7% sodium and/or potassium silicate
and/or colloidal silica and/or fumed silica and/or silica fume
and/or anhydrous silica. Using the Schutz automotive undercoating
spray gun (available from the 3M company of St. Paul, Minn.) or
another medium-to-large orifice gun (such as a sandblasting gun),
fine crushed gravel can be mixed in to achieve a sprayed concrete
of any type, including Portland cement. Phosphate cements can also
be sprayed through traditional paint spray guns, shotcreting
equipment or all sizes of sand blasting equipment, including hand
held equipment, with the additions of appropriate retarding and/or
lubricating admixtures, as detailed hereinbelow.
[0037] The cement compositions may be tailored to the desired end
use. For example, it is possible to activate the silica sources by
treating them with about 2-50% NaOH or KOH or MgOH solution, or
with a solution of about 2-50% phosphoric acid to increase their
reactivity. Likewise, it is possible to use potassium and/or sodium
silicate, in either liquid or powder form, to replace or supplement
some of the other silica sources and to fill in pores and increase
hardness. Likewise, liquid Na or K silicates, or mixtures thereof,
may be added as adhesion enhancers and accelerants, as well as
contributing to "self-healing" and smoothness.
[0038] Replacing high calcined MgO with low calcined dolomite, MgO
or CaO as the base increases coating strength and reactivity.
Alternately, a mixture of calcined MgO and dolomite may be used
with liquid phosphoric acid or phosphate salts as the cement
precursors, with total acid and base combined concentrations
ranging from about 5%-60% of the total cement mixture, more
preferably about 20%. Decreased acid-base concentrations mean
increased water concentrations, which yields better "wetting" and
slower drying, giving the acid more time to react completely with
as much base as possible, resulting in an enhanced hardness with
time. Using sawdust, guar, Berylex.TM., cmc's, or cellulosic fibers
increases the amount of water inside the matrix, yielding a slower
and longer and more complete reaction which typically results in
harder and/or less porous materials.
[0039] It is also possible to partially or completely replace MgO
with natural wood ashes, such as wood potash, as the base
component. The use of wood ash resulted in a smooth cement finish
and a very hard coating. The reaction rate is slowed by replacing
part or all of the MgO with slower reacting bases such as
dead-burned MgO or with ZnO, TiO.sub.2, Al2O3, Fe2O3, TiO2,
zirconium silicates, zirconium floc, cubic zirconium, zirconium
oxides, monoclinic zirconia (available from Carpenter Engineering,
Inc. of Bow, N.H.), barium sulphate, ZrOH or Fe3O4.
[0040] Adding adhesive admixtures or mixtures of mono sodium
phosphate (MSP) and aluminum phosphate yields a cement having
enhanced adhesion, as does the addition of chlorinated polyolefin,
other adhesion enhancing polymers, resins, glues, adhesives and
polymers such as moisture-cured polyurethanes. The advantages of
increased adhesion include greatly reduced rebound upon spraying
and less running and dripping on vertical walls and/or ceilings.
These adhesive phosphate cements make excellent mortars. For
spraying overhead or vertical walls, more adhesiveness is desirable
and MSP, or MSP and aluminum phosphate, colloidal silicas,
K-silicate, Na-silicate, silica flour or polymers may be combined
to admix to or to replace up to 20% of the primary phosphate
component of the cement. The additions of fine aggregates, such as
fly ash, silica fume, colloidal silica, and fumed into or in
combination with finer particles of phosphate salts and the base
oxide or oxides have been demonstrated to enhance the adhesion of
phosphate cement to substrates (both chemically similar and
dissimilar to the phosphate cement). Further, phosphate cement
adhesion may be improved by pre-treating the substrate with one of
the following: a solution of magnesium, calcium, potassium, and/or
sodium hydroxide; a suspension of one or more oxides of magnesium,
ammonia, potassium, sodium, and/or calcium; a suspension of one or
more phosphates of magnesium, ammonia, potassium, sodium, and/or
calcium. Moreover, phosphate cement adhesion may be enhanced
through acid-etching the substrate, such as with sulfamic,
sulfuric, muriatic or hydrochloric acids. Likewise, roughening the
substrate may also enhance adhesion. Additionally, unlike surface
charges may be imparted to the substrate and the phosphate cement
coating to further enhance adhesion therebetween. These phosphate
binders can bind/adhere to most materials including but not limited
to: themselves, fabrics, cloth, wood, plaster, portland cements and
concretes and mortars, gypsum cements and plasters, plaster holding
materials such as lath and chicken wire, roofing materials,
metal/plastic/natural fiber netting, meshes and screen, metals,
fibers, steel, and all building materials and other materials
having a minimum degree of surface texturing. Otherwise smooth
materials may be textured through etching, abrasion, or the like.
Phosphate coatings and cements are usually considered to be
structural materials, and some novel uses include: filling up empty
spaces in card boards or plastic shipping materials to add strength
and fire/heat resistance; filling the interiors or coating wood or
plastic or laminates such as vinyl windows with phosphate cements
or concretes in order to greatly strengthen same; and adding fire
and heat resistance and increasing insulation R values. For
example, application of a phosphate cement coating and/or filling
its interior may change a window from merely an inexpensive
residential-use window to an expensive commercial window, while
adding stability and fire resistance and increased R values, and
allowing for larger windows to be made based on a plastic or wood
frame.
[0041] The following admixtures, aggregates, have been found to
improve or modify the properties of the phosphate cements,
phosphate cements being acid-base reactive ceramic cements wherein
the acid is phosphoric acid (either liquid or as a phosphate salt,
usually an alkali-earth salt such as a phosphate of magnesium,
calcium, sodium, aluminum, zinc, or the like or ammonia) along with
a base that is usually calcined magnesium oxide, dolomite, calcium
oxide or the like, although it can contain other aggregates, such
as sand and/or stone. The characteristics of the resultant
cementitious product, such as a coating, may be tailored through
the use of one or more additives or other ingredients. For example,
replacing some of the phosphoric acid/salt with nitric acid results
in a modified binder system. Lithium, zirconium, and aluminum
oxides are especially useful where the composite will be subject to
high temperatures.
[0042] Hardness and the hardening rate of the phosphate cement
coatings may be impacted by the addition of Ca, Na, or Mg
fluorosilicates and/or hydroxides, multiple-phosphate salts,
phosphoric acid, magnesium silicate, aluminum oxides, hard metals,
cermets and ceramics, calcium fluoride, glass frit, zinc stearate,
boric acid, borates such as sodium borate, zirconium hydroxide,
silica dust, plastics, zirconium, iron, sodium tetraborate
decahydrate and aluminum oxides. Likewise, hardness may be
increased through the addition of Ca, K and/or Na ions from such
sources as feldspars, carbonates, and hydroxides, barium sulfate,
dolomite, calcined dolomite, sodium silicate, potassium silicate
flake and/or potassium silicates, zirconium oxides and silicates,
aggregates, phosphate salts, volcanic ash (such as Mt. St. Helens
Ash), mono magnesium phosphate (MMP), mono calcium phosphate (MCP),
Gibberellic acid, Rockcast.TM. polymer (from the Victor Co. of Des
Plaines, Ill.), and a novel use of colostrum as a very strong
dispersant and sequestrant. Using coal tar shampoo as a water
reducer, smoothing agent, and accelerator is novel. One preferred
cement composition exhibiting excellent hardness is a composition
containing ammonium phosphate cement (APC) as an inexpensive base
to which aqueous colostrum and mono-magnesium phosphate have been
added.
[0043] The addition of K, Ca, Zn, Zr cations or di-ammonium
phosphate or colostrum or a defoamer or sodium or potassium
silicates to ammonium phosphate cements adds significant strength,
eliminates off-gassing of ammonium and eliminates pin holes and
pock marks, leaving a smoother stronger composite at very little
additional expense, whereas Mg, Ca, Zn, and K phosphates are very
expensive. The replacement of magnesium phosphate or ammonium
phosphate with phosphates of calcium or potassium, or using them
along with Mg, K, Ca, Na, or Zn phosphates and sufficient water
allows cementitious reactions to progress even after the cement
sets up, i.e. the cement increases in hardness with time so long as
there is internal moisture to drive the reaction with the unreacted
acid salts and the base(s). This also provides some "self-healing"
properties. Alternatively, hard materials such as silicon carbide,
boron nitride, aluminum oxide, silicon nitride, hard technical
ceramics or cermets, hard metals, aluminum nitride, stabilized ZrO
and ZrO.sub.2, diamond, ammonium metavanadate, vanadium oxides,
tungsten carbide, molybdenum metal and/or oxide, and the like may
be added into the mix to provide an additional composite or
quasi-composite phase. Ultrafine particles of fly ash, silicon
boride, silicon carbide, boron carbide, aluminum nitride, aluminum
oxide and hard metals in the cement matrix also have the effect of
increasing the hardness of the resultant cement body or coating.
These particles are preferably spherical and may also be pretreated
with KOH or NaOH (or nitric, phosphoric or hydrochloric acids or
combinations of these acids) to increase their effectiveness.
[0044] Other additives that increase the hardness of the phosphate
cement compositions include: oxides of aluminum, manganese,
molybdenum, nickel, chromium and vanadium, aluminum paste,
zinc-aluminum paste, tin, silica flour, colostrum, steel, iron ore
concentrate or iron oxides alone or in combination with aluminum.
Hardness is increased in phosphate cements by adding in one or more
of the following: potassium silicates (preferably as powder, liquid
or flake); sodium silicate (preferably as powder, liquid or beads);
potassium feldspar; calcium feldspar, sodium feldspar, third
generation super plasticizers; phosphate salts; fly ash; metal
oxides; fine sized aggregate (including fly ash, phosphate salt
particles, and oxide particles); citric acid; wood ash or potash;
MCP; MKP, and polyphosphates of potassium and/or calcium (such as
di-calcium phosphate or tri-calcium phosphate); nepheline seyenite;
zirconium hydroxide, zirconium oxide and/or zirconium silicate;
calcium hydroxide and/or calcium oxide; fine particles of pre-cured
phosphate cement; silica fume; magnesium aluminum silicate
dispersant; sodium fluorosilicate; mono-potassium phosphate;
MetaMax.TM. (a Portland cement additive); about 1-20% of the total
weight of phosphates to be replaced by mono-sodium phosphate; iron
ore slag; grobbar, granulated blast furnace slag and/or iron
oxides; small particles of mineral colorants; liquid glazes used
internally in the mix, colloidal tin silica, trap rock from the
iron mines; silica sand (preferably in multiple sizes to optimize
PSD); potash; iron ore floc; ammonium perchlorate; sodium
hypochlorite; metakaolin; MCP or MKP with Dequest 2000.TM. or
Dequest 2006.TM.; Surfonyl.TM. (available from Air Products Co. of
Allentown, Pa.) surfactant; MCP anhydrous; MKP anhydrous; red iron
oxide; particulate aluminum foil (especially when used with one or
more of the following: NaOH or KOH and MKP or MCP and/or KCl or
NaCl); magnesium aluminate; potassium perchlorate; silica flour;
cmc's and cellulosic materials; zinc oxide; tin, very fine reactive
fly ash (for example, Micron-3.TM. (available from Boral
Technologies of San Antonio Tex.); dolomite (either calcined or
uncalcined); BPO catalysts; sodium methyl silicates; titanium
dioxide; Wollastonite (calcium silicate); fumed or colloidal
silicas, stabilized colloidal silicas, and/or silica flour; and
cordierite. Feldspar, and especially potassium and 0-9 micron sized
lignite flyashes, are excellent for filling pores in Portland
cement, as they generally have advantageous PSD's for filling
Portland cement pores.
[0045] Hard, smooth reactive cements are made by combining
phosphate cement with silica fume, fumed silica, perlite, colloidal
silica, sodium silicate, potassium silicate, one or more feldspars
(such as K-feldspar), MCP and/or MKP anhydrous, small and
preferably spherical seeds of phosphate cements including that of
magnesium and calcium phosphate cements, lignite and other flyashes
under 10 microns in size, air entrainer, steel and/or plastic
fibers and/or carbon fibers of two or more diameters and lengths,
and micron or nanoparticles sized aggregates. Portland cement can
be used in lieu of a phosphate binder for these reactive
cements.
[0046] OPC is also hardened by feldspars, colostrom, small
spheroidal seeds of OPC or phosphate cements, latest generation
super plasticizers, and Na and K silicates. Also, solvents and/or
other fuels (i.e., distilled petroleum products or the like) or
explosive materials such as kerosene, ammonium nitrate, ammonium
chlorate, strong oxidizers, hydrogen peroxide, nitro cellulose,
alcohols, methane, dried corn, gasoline, diesel fuel, lacquer
thinner and hair sprays such as Aquanet.TM. (manufactured by
Cheesebrough Ponds USA Co., Greenwhich, Conn.), Japan thinner,
and/or urea, when added to the slurry or spread on the hardened or
not yet hardened cements of above compositions can be ignited to
rapidly cure and densify the composites. These composites can be
made in-situ, resulting in very inexpensive and hard net-shape
products. Cmc's, sawdust or paper may be soaked with the fuel and
placed on the periphery of the material to be fired or placed in
layers within the material to be fired to more evenly heat the
in-situ composite. For sprayed coatings, fuel may be mixed into the
slurry (either with or without an emulsifier) before firing.
Alternately, the fuel may be sprayed, brushed or otherwise
topically applied to the substrate before applying the slurry, and
the applied cementitious material then sprayed with a top coating
of fuel before igniting same. Still alternately, fuel may be
topically applied on top of the cementitious coating and ignited as
the cement approaches or exceeds its initial set. These cements and
their composites may also be fired in a furnace. Ceramic fluxes
such as feldspars may be used in these firings. These phosphate
cements can be added integrally to ordinary Portland cement
materials. Also, a thermite reaction of iron oxide and powdered
aluminum can be mixed into the phosphate cements or mixed into
other metal or ceramic materials and lit with magnesium ribbon or
another high temperature ignition source to create flash fired
reaction parts in-situ or as a hardened coating. By using the
thermite ingredients, the need for placing the precursors in a
slurry is obviated, as the temperature approaches 4000 degrees
Fahrenheit and so the composite is a melt. Parts can be made in
molds or by ramming or shooting them through an extrusion die, via
a hydraulic ram, compressed air gun, or a spud gun.
[0047] The process of spraying concrete may also act to increase
its density. The density of sprayed phosphate cements may also be
influenced by such factors as particle size and shape, the particle
size distribution, or PSD, of the component materials, temperature
of the mix and surfaces, the oxygen content in the water, the
purity of the water, the reactivity of the mix, and the amount of
air mixed into the spray jet.
[0048] The use of chemical retarders to regulate the reaction rate
is important. The use of retarders, along with maintaining smaller
particle sizes of the components and maintaining a low temperature
cement system, is important in making cements sprayable. However,
smaller particle size means more surface area and faster reaction,
setting and hardening. Reaction rate may therefore be controlled
through variations of the PSDs of the precursors. Further, precise
temperature control is not always feasible, especially regarding
large scale construction projects and applications subject to
temperature extremes, such as from the weather. Thus, the use of
retarders, alone or with particle size reduction and/or temperature
control, is the preferred means of controlling the reaction rate of
the phosphate cement coatings. Accelerators are useful in
flash-firing the phosphate binder materials, and also for road
patching and road and roof coating and all types of coating in cold
weather, including the interior and exterior walls of commercial
cold storage buildings; the present material can be sprayed down to
20 degrees Fahrenheit.
[0049] The following as retarders have proven effective in the
control/slowing of the reaction rate of phosphate cements: citric
acid, acetic acid, boric acid, Borax.TM., zinc stearate, fine rice
husk ash (RHA), Berylex.TM., guar, Zr oxides, Zr silicate,
deionized water, distilled water, oxygenated water, water
containing water reducers prior to being introduced into the mix,
polycarboxylic acid or salt therefrom, hydroxycarboxylic acid or
salt therefrom, polyphosphonic acids or salts therefrom,
superplasticizers, water reducers, TSP, calcium citrate, colostrum,
calcium fluoride, sodium fluoride, soy emulsifiers, pyrophosphates,
distilled water, deionized water, alkali metal borates, sodium
silicofluoride, sodium and potassium carbonates, sodium nitrates
and nitrites, Dequest 2000.TM. and Dequest 2006.TM. (available from
the Solutia Company), potassium nitrates and nitrites, water
swelling clays, Laponite.TM., EZ Spread.TM., Castmate.TM. (a Dow
Chemical Co. trademark manufactured by H. C. Spinks Clay Co. of
Paris, Tenn.), diatomaceous earth and/or betonite (or other water
retaining clays which can be calcined), sodium
carboxy-methycellulose (CMC), other CMC's, ethyl celluloses,
Culminol.TM., Nexton.TM., ethyl methyl celluloses, ethyl
hydroxyethyl celluloses, saw dust, cellulose, phosphonates and
mixtures thereof. EZ Spread.TM. is air entrained and it retards set
and adds workability, freeze-thaw protection, elasticity and
increases pot life, work time and board life as does
Easy-Spred.TM.. Other effective retarding agents include:
relatively high pH phosphate salts (i.e., those having higher pH
values greater than mono-phosphate salts); smoothening agents (as
listed herein); potassium feldspar, Na or Ca feldspars, potassium
silicates, potassium hydroxide and/or potassium phosphate;
Berylex.TM.; iron oxides, ground blast furnace slag, aluminum
oxide, and acetic, citric and boric acids.
[0050] The use of a dispersant offers increased reaction rate
control of phosphate cements, and is often used in much higher
quantities than with Portland cement to achieve the same level of
control. During spraying, retarders and sequestrants are
particularly important, since physical intermixture of the cement
precursors (the acid and the base components) that occurs during
mixing and physical spraying drives the curing reaction even
faster, causing heat buildup in the spraying equipment, further
driving the reaction. These sprayed phosphate cements are excellent
overcoats/topcoats for Portland cement concrete and asphalt, and
they often eliminate the need for re-paving using the previous
gravel and pavement in place as the best possible, already
compacted mechanically and by freeze-thaw, road base. In addition,
these phosphate sprays, cements and concretes can be used as a
structural adhesive between layers of Portland. This allows a
Portland cement slab (such as a roof portion) to be coated with a
Portland cement such that the Portland cement coating bonds well to
the pre-existing Portland slab through an intermediary phosphate
cement layer. In other words, the phosphate cement layer is the
adhesive middle layer in a Portland cement "sandwich". Phosphate
cements react chemically with the unreacted calcium oxides and
hydroxides and silicas in the Portland cement layers, creating a
very strong bond for laminating the same or even dissimilar
materials together. This phenomenon likewise allows road patching
on Portland cement and asphalt roads with new Portland cement or
asphalt by merely by spraying or placing a coating of phosphate
cement between the old pavement and the new Portland cement/asphalt
overcoat. Also, a thin coat over freshly poured Portland cement
concrete (preferably applied as soon as the bleed water is gone)
eliminates the need for curing compounds and speeds initial set
while keeping the Portland cement moist for a longer time, thereby
producing stronger Portland cement concrete with fewer cracks and a
harder less porous surface with less heat shrinkage. It also
protects the poured Portland cement from rain and wind. Winds tend
to dry out Portland cements too quickly causing, heat shrinkage and
spalling and decreased strengths. Road markings and colors and art
work can be brushed or rolled or sprayed onto Portland cement,
asphalt or phosphate cements/concretes or pavements.
[0051] Alternately, reaction rate may be controlled by using a less
active base, such as zinc oxide, zirconium oxide, zirconium
silicate, high burn calcined magnesium oxide, iron oxide, or
titanium oxide to slow down the reaction and yield more pot life.
Likewise, a less reactive phosphate salt (such as phosphates of
potassium or zinc) may be used to control the reaction rate.
[0052] Another means of reaction rate control to increase pot life
is to use larger particle sizes for the cement precursors and
additives. Larger particles decrease the effective surface area for
a given volume or mass of reactants, thereby slowing the reaction
rate. Further means of slowing/controlling the cementitious
reaction include using slower acting phosphate salts of Zn or K in
addition to or in replacement of the above-mentioned salts and
using distilled, substitution of some of the phosphate ion source
with phosphoric acid, de-ionized and oxygenated water instead of
standard tap water. Alternately, additions of Berylex.TM., guar,
Easy-Spred.TM. (manufactured by the American Colloid Company of Mt.
Prospect Ill.), clays, colostrum or cellulose or combinations
thereof may be used to slow the cementitious reaction.
Additionally, it should be remembered that by keeping the acid and
the base components separated, pot life is increased.
[0053] Using the above described retarders and retardation
techniques, phosphate cement slurries may be produced that can be
sprayed, troweled, dipped, brushed, flowed, vibrated, stirred or
otherwise placed; the slurries so produced tend to be self-leveling
and can be self-filled into forms.
[0054] Conversely, it is sometimes desirable to accelerate the
curing of the cement coating. This may be accomplished by using
accelerants. Some accelerants include additions of a stronger acid,
or by adding more or more highly concentrated acid, nitric acid,
salt solutions such as sodium chloride or calcium chloride, more
and/or smaller seed crystals, aluminum, tin, tin oxide, faster
reacting oxides, calcium and/or sodium carbonates, yeast,
carbonated water, and/or heated water to the cement components or
admixture. Other accelerants include Mt. St. Helens fly ash;
Micron-3.TM.; volcanic ash; low or uncalcined oxides of magnesium,
sodium, and/or calcium; wollastonite; ammonium metavanadate; and
relatively low pH phosphate salts. It should be noted that in the
case of solid accelerants, the effectiveness of the accelerant
increases with its surface area to volume ratio. Additionally,
warming the target substrate surface will likewise accelerate the
cementitious reactions. Other accelerator additives include MgOH,
NaOH, CaO, CaOH, AlOH.sub.3, uncalcined MgO or dolomite, and/or KOH
additives. Hydrogen peroxide, and/or sodium permanganate also speed
set and hardening, as does metallic tin, polyelectrolytes such as
NaCL, chlorine, Na hypochlorite, and Cascade.TM..
[0055] The sprayable cement components may be made less abrasive,
so as to extend the life of the sprayer equipment, by using silica
flour, silica fume, perlite, class F and C fly ashes, fumed silica
and/or colloidal silica instead of coarser sand particles and rock
as aggregates. Additions of diatomaceous earth and/or bentonite
clay (or the like), in addition to smoothing the surface finish,
also act as excellent retarders and sequestrant and improve the
flowability of the phosphate cement slurry and assist in
self-leveling and self-consolidation. Additions of zinc stearate
also enhance self-leveling and self-filling properties. Additions
of cmc's, buffers, fumed silica, colloidal silica also improve the
finish as to defoamers and air entrainers and black iron oxide,
feldspars, liquid glazes, K and Na silicates (especially in liquid
form), nepheline seyenite, methyl methacrylate, silicate coatings,
wollastonite in powder form, potash, KOH, NaOH, resins,
Bermocoll.TM., multiple sizes of phosphates and two or more
phosphates such as MCP, di- and tri-calcium phosphates, KCl, and
the like. Powdered coating materials, both resins and metals, can
be used on and within the phosphate cements, as they can take the
heat required to fuse the colors and many metals and to enhance
their adhesion to the substrate. These phosphate ceramic cements
are great insulators against very high heat and fire and may be
used as refractories.
[0056] The appearance of the phosphate cement spray coating may be
aesthetically improved by using colorants and/or less abrasive
additive materials (see above). Patterns, both of different colors
and of different textures and combinations thereof, may be
introduced through additives. For example, a faux marble and/or
faux granite look may be created by the introduction of excess MgO
and colorants that do not disperse evenly, for example aquamarine
blue and others that are not wholly water soluble. This makes
beautiful randomly shaped swirls. Scattering colorants on the
coating while it is still wet is also possible. The final finish is
as variable as an artist's canvas. Wood potash, NaOH, feldspars,
KOH, MMA (methyl methacrylate), EMA (ethyl methacrylate) and other
plastics as additives yield a smoother finish, while the additions
of EMA and MMA and some moisture-cured polyurethanes also yield a
harder finish and often close pores. Additions of milder organic
acids such as vinegar and oxalic acid yield smooth finishes.
Colloidal silica, fumed silica, perlite, amorphous silica, sodium
silicate, potassium silicate, small sized class F fly ash, and
silica fume additives all yield smoother finishes and coatings
having less open porosity, providing increased water resistance and
better encapsulation of cements, mortars, and concretes. The
addition of boric acid, as in ceramic pottery, feldspars, iron
oxide can create a glaze when fired. Sodium silicate in sprays or
on the surfaces of cements or concretes or mortars can create a
glaze without firing, especially if it is repeatedly wet down. The
additions of plastics (polymers, elastomers, resins and the like)
typically yield nonporous cements having enhanced flexibility and
improved fracture, compressive, and tensile strengths. Asphalt,
Renolith.TM., Elvaloy.TM., ethylene terpolymer, ketone ethylene
ester, tin, and polymer additives such as BMA and EMA and
elastomeric coatings also may be added to Portland cement, yielding
similar results; the Portland cement may be poured or sprayed. The
addition of the above-listed plastic and/or elastomeric materials,
such as Elvaloy.TM. or rubber particles, into a phosphate ceramic
coating enables these strong cements to be sprayed onto materials
such as asphalt, roofing, pavements, and the like that experience
compression. Phosphate cement coatings containing such elastomeric
and/or plastic additions are less susceptible to the damaging
effects of thermal cycling (repeated stressing of the material due
to differential thermal expansion of the coating and substrate), UV
rays, freeze-thaw cycles and accordingly extend the life of the
coated substrate. In other words, the elastomeric and/or plastic
particles distributed throughout the phosphate cement matrix act to
absorb some of the compressive and/or tensile forces acting on the
cement due to the presence of heavy loads thereon or thermal
cycling, thereby reducing the incidence of crack formation and
propagation and of material creep. It should be noted that some of
these additions, such as Elvaloy.TM., require an energy influx in
order to initiate polymerization or "setting up"; this energy
influx is partially satisfied by the exothermic heat of curing of
the phosphate cement.
[0057] Powder spraying is accomplished on phosphate cement parts
and surfaces via electrically grounding the cement by spraying it
with a solution of an electrolyte such as NaCl or KCl in water and
placing a conductive metal on the wetted surface to electrically
connect the same to a ground potential and then spraying it with
ionized power coatings from a negatively charged electrostatic gun.
The fusing heat of 275-400 degrees Fahrenheit for ten minutes is
thereafter applied to fuse, smooth and harden the coatings. Powder
coatings are made by various manufacturers and are typically
polyurethane, polyester, Triglycidyl isocyanurate and blocked
polyisocyante materials. One such manufacturer is Morton
International, Inc. of Chicago, Ill.
[0058] Ductile and elastic strengths are improved by using fibers,
preferably graded and multiple types of fibers in the same mix.
Strength may likewise be improved by inserting steel or plastic
rebar, or filling pipes or mats with cement. Adding sodium and/or
potassium silicates to phosphate or portland cements adds to these
two strengths. Materials for pipes can be pvc, steel, iron,
plastics or bamboo. By using the self-filing additives and smaller
particles and no rock aggregates, in either portland or phosphate
cements, mats can be used as fibrous rebar, wherein the cements
infiltrate the mats for strength and the mats improve ductile
strength. By using multiple gradient fibers of two or more types
and two or more materials and using same up to 15% by volume of the
portland or phosphate cements, ductility is increased.
[0059] Elastic, fracture, tensile and ductility are increased by
adding in resins, especially non-deforming plastics, as denoted
herein and also by making resins within the portland or phosphate
concretes.
[0060] Silly Putty, Dilatant.TM. (available from Dow Coming of
Adrian, Mich.), Slime, shock absorbing polyurethane such as
Adzorb.TM. (available from the New Balance Shoe Company of Boston,
Mass.), Hytel.TM. (made by the DuPont Chemical of Wilmington,
Del.), gels, fibers, polyurethanes, waterborne and solvent
plastics, epoxies, moisture-cure resins and gums all contribute to
toughness and elasticity. In addition, the formation of polymers
within the composite, after the Portland or phosphate cements have
been thoroughly wetted and mixed, keeps water and these elastic
shock absorbing materials inside the composite in the pores and
vacancies and allows for the crystals to grow for months or years
afterwards, continuing to fill in spaces and pores, and to continue
to grow and self-heal, especially in calcium phosphate cements and
when using colostrum. Further, these shock absorbing materials act
like water balloons to cushion the shock and to hydraulically
spread any impact force evenly over a great surface area and
therefore increase fracture strength. The use of nanophase
particles produces a smoother finish. If the nanophase particles
are of reactive material, such as silica fume, volcanic ash or
reactive flyash, nanophase MgO and small micron flyashes, they act
as catalysts in phosphate and/or Portland cement compositions.
[0061] In general, smoothness and a reduction or elimination of
pockmarks, surface irregularities and pinholes in magnesium and
ammonium phosphate cements is achieved via the addition of one or
more of the following: fumed or colloidal silicas; stabilized
colloidal silicas; silica flour; oxides generally less active than
calcined MgO, such as, for example, Fe.sub.2O.sub.3 or
Fe.sub.3O.sub.4; Al.sub.2O.sub.3; kaolins; smectites; hectorites;
potassium phosphates; potassium oxide; potassium hydroxide;
Zantac.TM.; air entrainers, defoamers, nitro cellulose; cellulosic
materials; Kelco.TM. and cmc's and other cellulosic materials
(which also provides wash-out protection and facilitate
self-leveling and self-filling/self-consolidating); and gradient
sizes of phosphate salts, fly ashes and aggregates. Surface
smoothness may also be enhanced by using phosphate salt additives
of differing solubility rates. Surface smoothness may likewise be
enhanced by using as poly-phosphates (such as, for example,
tetra-potassium phosphate, tri-calcium phosphate and di-calcium
phosphate) and lower pH of bases and higher pH of phosphate
solutions and more water when using liquid phosphoric acid. The
smooth finish makes the phosphate cements with finer aggregates
suitable for underlayment, which can be featheredged and sets fast
enough that a tile setter can finish grout the tile within an hour
and one-half of laying it. Such grouting substantially does not
shrink, has excellent bonding strength and is extremely resistant
to water damage. Such material is also usable for patching wood,
concrete, tile and asphalt.
[0062] Defoamers and ceramic additives as well as the addition of
potassium ions from such materials as: KOH, K feldspars and other
feldspars, can be used to smooth out and eliminate the pinholes and
gas bubbles in ammonium phosphate cement, enhancing the appearance
and reducing the porosity of this phosphate cement.
[0063] Phosphate cements, glazed or unglazed, may be used on
surfaces including, but not limited to, wood, metal, Portland
cement concrete, drywall, Styrofoam.TM. insulation, plywood,
Dry-Vit.TM. a replacement for stucco exterior, plaster, stucco,
adobe, wood and asphalt shingles, shakes, tar paper, roofing
materials, roof boards--with or without chicken wire or other
material to enhance adhesion, basement walls, Portland cement
concrete and asphalt roads, plaster finishes, all types of flat and
pitched roofs cement bricks and blocks, and ceramic bricks and it
adheres to itself, even if the phosphate substrate or joint is
cold. These phosphate cements react chemically with the unreacted
CaOH and silicates, Portland cements, concretes, plasters and
mortars. Adherence is enhanced by using small particles and more
reactive particles, as well as electrostatic charging, magnetizing,
sticky materials such as potassium and sodium silicates, less
water, oppositely charged chemicals and chemical additives and
polyelectrolytes, other admixtures and plastics.
[0064] Different aggregates added to the cement mix change the
appearance, strengths, costs, rheology, and may also change the
equipment requirements. For instance, hard materials such as
glasses or metal oxides may be added to form a second phase in the
cement, imparting increased hardness properties to the final
product. Likewise, fibers, such as those of metal, carbon,
Kevlar.TM. (by Dow Chemical of Wilmington, Del.), graphite, glass,
crushed or recycled glass, or plastic or combinations thereof and
in single or multiple lengths, diameters, and shapes, and in
multiple, preferably gradient sizes, may be added to the pour or
the spray mixes to form a fiber-reinforced cement composite in
quantities of up to 15%, yielding composite with enhanced, tensile
and ductile properties, especially when two or more different types
are used and are used in different sizes compatible with the
aggregate and the ingredients to obtain optimum PSD, along with the
latest generation of super plasticizer to form the most dense
non-porous cements, mortars, coatings and concretes with great
tensile, ductile and elastic strengths.
[0065] Using the two-stage method, additives such as guar, clay,
bentonite, fine sawdust, corn starch and other starches, small wood
chips/fibers, cellulosic material, CMC's methyl cellulose, ethyl
methyl celluloses, ethyl hydroxyethyl celluloses, soy dispersant,
tri-sodium phosphate, aluminum and sodium phosphates, and
thickeners result in increased adhesion and/or increased cushioning
and encapsulating and holding effects upon the aggregate and upon
the sprayed cement as a whole, thereby reducing rebound.
Kelco-Crete.TM. or other gums and cmc's are used along with water
reducers help to prevent washout of cement fines and chemicals and
fine aggregates in underwater construction projects.
[0066] The addition of water in an amount sufficient to
substantially match the viscosity of the slurry to that of
water-based acrylic paints or enamels increases the sprayability of
the cement mixture and slows the reaction rate of the coating. The
particles are maintained in suspension/emulsion/gel state via the
acid-base reaction. Thickeners such as silica flour, cellulosic
materials, methyl cellulose, sawdust, flocculents, corn starch,
gums, wheat starch, powdered gelatin, guar, polyurethane and
Berylex.TM. may be added to maintain a viscosity suitable for spray
coating. Soy lecithin has been found to be an excellent wetting
agent, dispersant and emulsifier. Other emulsifiers include
high-wetting cellulose fiber, yielding high bulking for more air
entraining and longer wetting time (the mush makes for a soft place
to hold more cement and to cushion the silica/aggregate hitting the
hard surface of application, hence preventing rebound), starch
(wheat or corn) along with soy. One preferred source of soy is ADM
(Archer Daniel Midland) Ross & Rowe Lecithins: R & R
551.TM. a Soy Lecithin. R & R 551 is a nonionic surfactant and
is propylene glycol and acetone insoluble. R & R 551 is
non-edible. R & R 551 is used as a wetting and suspending agent
in water based paints, is highly dispersible, and works well in
phosphate cements and in Portland cements. Another preferred
emulsifier/wetting agent is ADM's Yelkin TS.TM.. The above-listed
ADM products also supply carbon (a good hydrophobe), as do wood
potash, saw dust, organic resin, and carbon black. The use of an
emulsifier enables the mixing of the phosphate binder or Portland
cements and/or surfactants with non-aqueous plastic finishes, such
as epoxies, urethanes and other solvent-based coatings, and
elastomeric or hard plastics. These phosphate cements also act as a
filler in plastic adding compressive strength and speeding set
times, all while being inexpensive and allowing for the forming or
injection of net shaped parts in-situ without the need for firing
or machining. The strong acids and bases in the phosphate cements
also polymerize or aid in the polymerization of carbons and carbon
ingredients such as wood resins, especially pine resins and
creosote from oak, thus adding to elastic strength and the filling
of pores.
[0067] The toughness and/or resistance to facture may be increased
through the additions of polymer powders or granules (i.e., rubber
particles) to the cement precursors. Adding from about 1% to about
50% of elastic, shock-absorbing materials can significantly
increase the shear, ductile, fracture, and tensile strength of the
resulting cement composition, especially if the elastomeric
material does not deform under the shock, for example non-deforming
elastomeric plastics. This effect is not limited to phosphate
cements, and can be used in Portland cements, although in bulk
applications it must be recognized that the compressive strength
and other cement bonding related properties may suffer as higher
percentages of toughness additives are added. These disadvantages
are partially mitigated by the thin-film nature of phosphate cement
sprays, making the use of toughness increasing additives
particularly attractive therein. Some toughness-enhancing additive
compositions include, but are not limited to: polyvinyl acetate
(PVA); a mixture of PVA and boric acid or sodium tetraborate
(preferably about 2:1); a mixture of PVA and liquid starch
(preferably about 1:1); a mixture of PVA and boric acid or sodium
tetraborate; and ground hard rubber/rubber crumbs. Also, some
commercial products, such as foams, the line of Rubinate.TM.
di-isocyanate moisture-cure resins (available from the Huntsman
Polyurethane Company of Auburn Hills, Mich.), and the New Balance
company's ABZORB.TM. product which is a shock absorbing
polyurethane elastomeric which absorbs the shock with little or no
displacement/deformation to the shock absorbing materials. Archer
Daniel Midland's R 551 soy emulsifier product and other emulsifiers
have been found to assist in the distributing these elastomeric
products (even the solvent based epoxies and urethanes), evenly
throughout the cements. Phosphate cements which can encapsulate
and/or chemically combine with heavy metals and even low level
radioactive materials to render them inert, may similarly
encapsulate or react with VOC's to likewise render the VOC's inert
or at least encapsulated for the protection of humans and the
environment. Adding Ductal.TM. to phosphate cements as an additive
further increases ductility and fracture strength, closes pores,
often retards curing, and adds smoothness to the surface. Adding
phosphate cement binder (alkaline earth metal oxide or hydroxide
along with one or more alkaline earth phosphate salts or ammonium
phosphate salts) as additives accelerates the set and increases the
adhesion of Portland cements and also of Ductal.TM..
[0068] Moreover, in addition to providing enhanced toughness and
crack-resistance in the cured cementitious coatings, the additions
of the toughness enhancing polymer particles also decrease rebound
problems during spraying, enhancing the adhesion of the sprayed on
phosphate cement coating to the target.
[0069] The magnetic properties of the phosphate cement may be
tailored through the additions of such additives as iron filings,
ferromagnetic iron oxides, conductive carbon black, magnets, and
powdered magnetic and ferromagnetic materials. The introduction of
magnetic materials into the phosphate cement forms may provide
radio frequency shielding and/or allow the coatings to function as
magnets and/or as antennas which may be included on or within a
whole road or building foundation or sprayed surfaces thereon. The
magnetic properties of the phosphate cement coating or of Portland
cement may also be influenced by providing a metallic underscreen,
such as through the placement of a copper or aluminum wire mesh
screen underneath or within a phosphate cementitious coating,
cement, mortar or concrete.
[0070] The electrical properties can be tailored or tuned via
addition of magnetic/electrical ingredients as above and including
but not limited to metallic powders and slurries containing: Cu,
Al, Ag, Au, Fe, Sn, conductive carbon black, polyelectrolytes, wire
screens, rebar or metal particles or wires made of
electroconductive materials and/or metals and/or conductive organic
chemicals.
[0071] Hardware
[0072] The present invention works in all types of commercial
sprayers/guns, even such sprayers as automotive-industry spray guns
made to spray thin solvent coatings such as lacquers, enamels and
urethanes and also water based coatings such as acrylics. The only
spray equipment now available is designed for "shotcreting" and is
very large, expensive and inefficient. As much as 40% of the
"shotcreted" material is lost to rebound, and the product can only
be applied in very thick and rough surfaced layers. The off the
shelf Sears Roebuck & Co. of Arlington Heights, Ill., hand held
sand blasting gun works well also, as do top loading spray guns
wherein the material containing container/can is located above the
spraying orfice which requires much less air pressure to vacuum
draw the material up to the spraying chamber/orfice.
[0073] Until now, it was not possible to spray cements using
coating guns because the cement thickness and viscosity were too
great, resulting in a clogging of the paint guns' needle valves and
spray tips and internal flow piping. Moreover, the sand and
abrasive oxides in the cement catastrophically abrades the needle
valves and spray tips of traditional spraying equipment. Increasing
the amount of retarders and sequestrants allows the spraying of
fine aggregates such as fumed and/or colloidal silicas, silica
flour, and precipitated silicas to make fine, thin and attractive
spray coatings. If particularly abrasive materials are sprayed, the
spray gun components (valves, tips, etc.) may have to be
accordingly hardened.
[0074] The preferred sprayer for the above-described phosphate
cements is the 3M BODY SHUTZ APPLICATOR GUN.TM., available form the
3M Corporation and sold as part no. 08997 from 3M's Adhesives,
Coatings and Sealers Division/3M in St. Paul Minn. 55144. The 3M
SHUTZ gun is made to coat auto rocker panels with "chip resistance"
coatings. The gun has no spray tip and a large orifice and few
moving parts to clog up or wear out. With large diameter flow,
short flow length, no spray tip and no spray orifice, clogging or
packing up of the gun is greatly reduced and when it does it can be
easily flushed.
[0075] For fine spraying, any paint or automotive paint gun may be
used with compositions containing sufficiently low amounts of
abrasives. The silica sources for fine spray compositions are
preferentially silica fume, fly ashes, sodium silicate, potassium
silicate, and/or fumed silica, amorphous silica or colloidal silica
as a replacement for the sand. This results in much less abrasion
to the spray gun, less packing up and/or clogging of the gun,
assists in eliminating rebound, and makes a fairly smooth surface.
About 5-10% NaOH or KOH or sodium or potassium silicate or
combinations thereof, may be added to the sodium or potassium
silicate and mixed in prior to adding it to the mix for smoother
spraying.
[0076] Other sprayers useful with the present invention include
standard air pressure paint guns, HVLP guns, LPLV guns, airless
guns, pump fed guns, pumps, sand blasting guns, shotcrete guns,
gravity fed guns, electrostatic guns, undercoating guns, and
suction type guns.
[0077] It should be noted that the phosphate cement slurry behaves
thixotropically, and that the thixotropic character of the slurry
may be modified and controlled through the use of thixotropic
additives. Accordingly, the pot life of the slurry may be extended
by stirring (either by hand or mechanically) or vibrating the
slurry. Moreover, the spray gun used to apply the phosphate cement
may be configured to agitate or to otherwise provide turbulence to
the slurry contained therein to likewise extend its pot life, such
as putting air or spurts of air, or angling and/or having an
opening for the vacuum air or pressurized air in the "paint can"
with a threaded or Archimedes screw interior, causing the air to
become turbulent and providing ongoing and regulated mixing of the
slurry.
[0078] Portland and phosphate cements and coatings are made
self-leveling and self-filling/self-consolidating via additives as
described above and including air entrainers, ethyl hydroxyethyl
cellulose, cellulose ethers, cellulose, methyl hydroxyl propyl
cellulose sometimes known as Culminol.TM., Bermocoll.TM., and
starch. The effect of self-leveling may be enhanced through the
addition of one or more of the following to phosphate cements:
smoothening agents or additives (listed separately herein);
multiple gradient sizes of one or more of the following: alkaline
earth phosphate salts, fly ash, metal oxides and aggregates;
substantially spherical aggregates and fly ashes; second, third and
fourth generation water reducers; Sulfonyl.TM. (available from the
Air Products Company of Allentown Pa.); Ductal.TM.; guar; various
natural and synthetic gums; Kelco-Crete.TM. (a self-consolidating
and anti-washout underwater Portland cement additive); Sikament
100SC.TM. (an anti-washout Portland cement additive by Sika
Corporation of Sweden); metal carboxylmethylcelluloses (cmc's);
potash; barium sulphate, and cellulosic materials in general,
included untreated and chemically treated cellulosic materials.
Similarly, the property of self-consolidation may be enhanced
through the addition of one or more of the following to phosphate
cements: Sulfonyl.TM. surfactant; Dequest 2000 or 2006
sequestrants; multiple sizes/gradients of alkaline earth and/or
ammonium phosphate salts; multiple sizes/gradients of fly ash or
other aggregates; gums, colostrom; CMC's, multiple sizes/gradients
of metal oxides and/or phosphate salts; wetting agents; air
entrainers, and Kelco-Crete.TM..
[0079] Instant densification of a formed phosphate cement may be
achieved through placing an exothermically reacting solvent (such
as a petroleum fuel) on or within the curing phosphate cement and
then igniting the exothermic reaction. Examples of exothermically
reacting coating materials include alcohols, diesel fuel, gasoline
(with and without an emulsifier) and explosives, such as powdered
nitro cellulose or black powder or the like and liquid explosives
such as powdered aluminum and ammonium nitrates and ammonium
perchlorates suspended in diesel or other fuels. The phosphate
cement hardens and densifies due to the heat of the exothermic
reaction.
[0080] Applications
[0081] The following is a non-comprehensive discussion of some of
the possible uses of phosphate cement coatings, both as sprayed and
as otherwise applied. In addition to the traditional cement uses
(blocks, slabs, and the like), the present invention may be used in
the following applications:
[0082] Coatings--for floors and slabs (see FIGS. 1-3), overcoating
roads, driveways, parking garage decks and ramps, bridge decks and
sidewalks along with replacement of ceramic tiles, building walls
(both inside and outside), drywall and plasters, plywood, siding,
roof plywood, shingles both cedar shake and asphalt, coating
asphalt and all concrete surfaces including replacing plasters and
asphalt damp-proofing. The rougher the surface, having more surface
area, the stronger the bond to the surface it is applied to.
Coating properties such as flexibility and toughness may be
modified through the additions of appropriate amounts of additives
to minimize the effects of differential thermal expansion and/or
the inherent flexibility of the coated member.
[0083] The present invention may be used for waterproofing and
decoration. For example, basement walls may be coated to prevent
water penetration and also to provide a quick finish if the spray
has a white or other colorant component, thereby removing the
requirement of framing and drywalling. Also, the exterior of houses
and commercial buildings may be coated with phosphate cement in
lieu of wood siding or brick or stone by putting up foam insulation
and coating it with a rough coat ("scratch coat") of Portland
cement plaster, gypsum plaster or phosphate cement, followed by a
finish coat of phosphate cement or just one coat of phosphate
cement.
[0084] Additionally, elements of the present invention may be
combined with traditional paints to provide painted coatings having
enhanced adhesion and wear properties. Additions of one or more of
the herein named phosphate salts, either alone to react with the
carbonates, oxides, some sulphates, nitrates, and/or titanates in
the paint, or with oxides or other bases named herein such has
lime, KOH or feldspar or silicates and other reactive minerals or
substances such as iron or aluminum oxide colorants and fillers,
zirconium oxides and silicates, in powder or liquid form, to
traditional liquid paint compositions, produce a paint composition
with enhanced adhesion, toughness, scuff resistance, water
resistance, chemical stability, oxidation resistance, durability
and an increase in overall lifetime. The addition of phosphate
salts or binders to paints cause a chemical reaction with oxide
and/or carbonate components to yield an elastomeric ceramic coating
that is chemically bonded to the substrate and/or to prior coatings
of itself. The coating has the advantage of remaining breathable
while enjoying increased flexibility, thermal cycling and creep
resistance, and toughness. Optionally, additional silica and/or
ceramic fillers or aggregates such as flyashes may be added to even
further enhance the durability of the coating. These phosphate
binders when added to silicate coatings will strengthen them and
make them sufficiently hard and waterproof to coat concrete floors
(such as warehouse floors), bridges and parking decks.
[0085] Adding the binder with or without flyash or other silica
sources greatly improves many coatings including paints, especially
exterior coatings such as Duration.TM. (made by Sherwin
Williams-Company of Cleveland, Ohio). Coatings or paints containing
one or more of the following react with phosphate or phosphate
binder or phosphate binders with silica additives: oxides of Ca,
Mg, Zn, Ti, K, Zr, Co, Al, Ni, MO, Cr or V; silicas (such as silica
sand, silica flour, colloidal silicas, silicates of alkaline earth
metals and iron, zirconium, sodium and potassium, micas, nepheline
seyenite, magnesium-aluminum silicate, aluminum silicates and
talc), hydroxides of Ca, Mg, Zn, Ti, K, Na, Zr, Co, Ni, Al, Ni and
Cr; carbonates of Ca, Mg, Co, Ba, Li and K; barium titanate; some
polymers; acids (such as boric, tartric, acetic, citric or oxalic);
and nitrates of Na, K, and Ca. The phosphate binder adds heat
resistance, compressive strength, durability, scuff protection,
hardness, shear strength, UV resistance, and heat and electrical
insulation and increases adhesion and wear life. The
phosphate-containing additives can be in the form of a dry powder
mix in a packet ready for the user to merely toss in when the paint
is mixed. Alternately, the additives may be mixed in to each roller
tray or pre-mixed with the paint in the can (including liquid and
spray paints). The phosphate binders can be added to clay pottery
slurries to make rapidly curing greenware. In this way, finished
ceramic pieces from pottery to tool bits can be made in very short
times without the need for firing.
[0086] When air entrainers are added, the coatings become even
better electrical and heat insulators, which saves on fuel bills.
Adding the binder with or without flyash or other silica sources
greatly improves silicate coatings which are beautiful mineral
coatings based on potassium and/or sodium silicates but which are
not very hard nor are they water resistant enough to be used for
outdoor floors, indoor floors, roofs, pavements or other wet or
harsh applications.
[0087] Roofing--the present invention can be sprayed right over the
plywood or other roof "decking" as it is fireproof and water proof
and can be made any desired color (or put on two-toned). This
entirely eliminates the need for: shingles, cedar shakes, roof
tiles, metal roofs, siding, exterior or interior painting, and the
like. Holding strips, wire, or mesh may be tacked to the roof
surface to provide a textured substrate for the sprayed cement,
allowing enhanced adhesion. A plastic pattern or form may be used
with the cement spray to modify the appearance of the cement
coating to produce an illusion of slate, wood shakes, or tile. A
plastic pattern can be used, just as is now used to for over
coating concrete with Portland cements or concretes (which have no
reactive adherence and often have thermal cycling problems), to
make the "covered over area" which prevents the coating from
touching the concrete surface, look like "mortar joints" between
the faux paving brick, cobblestone or slate appearing concrete
surfaces. A brown or reddish brown colorant provides an attractive
way to waterproof aged cedar shake roofs, eliminating the need for
expensive re-roofing. Old cedar shakes provide the irregular
pattern and depth and thus the classic look is not lost. Cedar
shake roofs and expensive and slate roof tiles and clay roof tiles
are very expensive. Cement roof tiles are expensive and heavy and
the cement, cedar and slate all require much skilled labor.
Phosphate cements and thin reactive cements where the cement binder
is Portland or aluminum can make good roof tiles or slates if the
aggregate is small and preferably light in weight. These cement
coatings make great overlays for pavements, driveways and sidewalks
and make excellent roof coatings, preferably in a warm climate
where the ceramic coatings with air entrainers and surface or
integrally colored with white mineral colorants/oxides or
photochromic materials to keep the buildings much cooler. Such
ceramic roof coatings have the advantage of substantially longer
life than their traditional counterparts and are immune to damage
from ultraviolet light. For walls, the present invention phosphate
cement coatings may be made to resemble marble also and can be
finished coated with paints or even harlequin coatings. All these
phosphate cements can be machined and polished. Both interior and
exterior walls may benefit from cement spray coating which leaves a
hard impervious smooth or textured insulated ceramic very long life
coating. Shingle, tar, asphalt, tar paper, wood, plywood or
sheathing board roof materials can be spray coated with phosphate
cement to eliminate tearoffs and the need for replacement roofing.
Reflective or absorbing pigments (such as white or black pigments)
may be added to decrease or increase the heat absorbing properties
of the coating to saves on energy bills (depending upon the ambient
environment); likewise, the coatings may be formulated to be air
entraining to further enhance their thermal insulating
properties.
[0088] This phosphate cement spray-coating works well for mortaring
bricks and adhering the layers of laminate materials. Phosphate
cements especially with elastomeric ingredients and small particles
make excellent adhesives for laminates, the elastomeric ingredients
allow enhanced toughness, analogous to the thin layer protein layer
in between the brittle calcium carbonate layers of a conch shell or
the glue layer between the wood/fiber layers of plywood. Fibers in
the phosphate cements also contribute to ductility and elastic
strength, especially if they are oriented or aligned for maximum
strength and especially if they are steel or aluminum or high
strength carbon fibers or fiberglass. The spray coating also works
well to cover asbestos or silica dust-containing insulation to
encapsulate the asbestos or silica dust, and even chemically bond
the dust into the cement matrix.
[0089] Prefabricated or temporary structures may be produced by
spray coating insulation foam blocks and/or forms in situ with a
phosphate cement coating. The cement adds strength, durability,
waterproofing, fireproofing, and thermal insulation (air
entrainment) to a structure. The cement coating also acts as an
adhesive to hold the structure together, eliminating the need for
conventional fasteners.
[0090] Sprayed phosphate cement coatings can also be used to
reinforce and waterproof drywall, wood and plywood and tar paper
and roofing membranes, which are susceptible to water damage and
has little structural strength of its own and must be painted even
for interior use. Also, the hard coating strengthens and adds life
to drywall which otherwise is easily penetrated.
[0091] Tuckpointing--phosphate mortars and cements strongly adhere
to old mortar in the joint and to adjoining brick or cement blocks,
and can be sprayed or squeezed into the joint. Portland cement
mortars suffer from the disadvantage of having to be slowly applied
into the joint from a small palette or mortar board with a small,
thin trowel, a process that is time consuming and labor intensive.
The porous highly air entrained Portland cement mortar is the
weakest and most porous part of a brick wall. The phosphate cement
slurries of the present invention are faster and easier to use,
stronger, tougher, less labor intensive and less porous than
ordinary Portland cements.
[0092] Exhaust and heat shielding--Dipping and/or spraying a thin
coating of phosphate cement on the interior or exterior of exhaust
pipes, engine parts, space travel vehicles, aircraft shells, rocket
coatings, mufflers, catalytic converters, exhauster headers and
manifolds, yields a ceramic coating on the inside, the outside, or
both. The coating protects the metal from chemical attack as well
provides thermal insulation. Phosphate coatings can also provide
ceramic protection of furnaces, heat ducts and other heat
generating and heat carrying equipment. Phosphate cement coatings
may also provide the fire protection of building materials,
including structural steel.
[0093] Environment--coating heavy metals, walls of sewer and septic
systems, interior and exteriors of man holes, pre-coating concrete
pipe so it is more water proof and resistant to corrosive chemical
(acid and alkali) environments. Concrete water pipe that is not
waterproofed loses an astoundingly high percentage of water, as it
is very porous. Phosphate cement may also be sprayed or otherwise
coated onto asbestos-containing structural members to encapsulate
the asbestos and reduce or prevent the incidence of exposure,
thereby creating artificial reef homes for fish and marine
wildlife.
[0094] Pavement--the present invention can be used as a concrete,
mortar, cement or coating and as a strong inert aggregate or as a
filler material in other materials such as in plastics, other
cements, and concretes. The phosphate cement of the present
invention bonds to itself, concrete, and asphalt and can be
aesthetically colored with oxides or other colorants. Adding a
cement coating to asphalt provides the benefits of increasing the
surface hardness, reducing surface cracking, decreasing water and
chemical intrusion, decreasing rutting and buckling caused by
softening asphalt in high temperatures, decreasing UV damage, and
prevents "sweating" of tar and oil from the asphalt surface,
increasing road life and decreasing skid risks. Light colorants
could be added to reflect away light and decrease road temperature,
thereby reducing thermal cycling and saving the tear out and
re-paving of asphalt and Portland cement roads. Filling the cracks
and spalling in concrete and asphalt pavements along with patching
the pot holes and then coating the surface with the present
invention can often avoid the need for tearing out the old concrete
and re-paving the road, saving vast amounts of tax monies and
environmental problems and dumping fees.
[0095] Curing concrete--spray phosphate cements on top of OPC
(ordinary Portland cement concrete) when the bleed water disappears
or is nearly dried up, and that holds curing water in the OPC,
resulting a slower and more complete curing reaction and harder
concrete. It also yields a harder and more chemically stable
phosphate surface coating. The phosphate coating further resists
road salt (calcium chloride) and water, protecting included rebar
from rust. Further, spraying phosphoric acid on the top of the
concrete reacts with free CaO and CaOH to make an in situ coating
that penetrates and chemically binds to the Portland cement
pavement or slab. The use of phosphate cements as curing agents and
top coats/overcoats on Portland cements would greatly increase the
current quantities of phosphate cements used today. The extra
expense would be more than offset by the increased life of the
coated pavement. The savings in re-paving roads and bridge and
parking decks alone necessitated by infusion of NaCl road salt
along would save untold dollars each year. Road salt gets into the
Portland cement pores and rusts the rebar, which expands and breaks
up the Portland cement concrete; a phosphate cement coating would
substantially retard such salt intrusion while simultaneously
reducing wear. Also as a curing enhancer for Portland cement, a
phosphate cement coating would prevent premature evaporation and
elimination of the original water in the Portland cement
understructure, causing the Portland cement to more completely
react during curing and contributing to increased compression
strength. Phosphate cements are attractive coatings for rebar (even
rusty rebar) since they greatly reduce the ability of road salt
and/or other chemicals to reach and react with the ferrous rebar.
This greatly increases the life of Portland cement highways,
parking and bridge decks. Likewise, coating the hulls of ships to
protect them from rust, salt water, and barnacles making for less
maintenance, less downtime, and possible slightly better speed
through the water.
[0096] Rust resistance/conversion--phosphate cements convert the
ferric rust (iron oxides) to inert iron phosphate silicates.
Preferably, for rust conversion, Ca and K nitrates and/or nitrites
are added to the cement. The encapsulating and non-porous and pH
neutral (the pH can be easily tailored) features of this reactive
cement can all contribute to preventing the rusting of steel
reinforcement within the concrete. Dipping or spraying new or rusty
iron rebar or structural steel members with these phosphate cement
coatings (especially ones containing silica fume, fumed silica,
and/or reactive clay), yields reinforcing members that are
impervious to water and salt corruption and chemical attack.
[0097] Artificial Reefs: Phosphate cements may be used to cement
together concrete building units, such as cement blocks, to produce
an artificial reef. Such a reef could be emplaced to attract and
hold fish, prevent erosion, or shore up an eroding reef to prevent
catastrophic change to an existing ecosystem. Moreover, wet
phosphate cement can be applied to either the inside or outside of
the blocks and then sprinkle and/or fertilizer and/or seeds of
water plants onto the surface of the wet cement, thus creating an
artificial reef with its own feed source and more ability to hide
and to have microfood organisms and small food fish with which to
attract the larger fish.
[0098] Preferred Mixing Process
[0099] The following steps describe one preferred mixing
process:
[0100] a) add the retardants: wetting agents, superplasticizer,
buffers, water reducers, defoamers, sequestrants or combinations of
same to the water (preferably deionized or distilled water) which
has been chilled or to which crushed ice or crushed dry ice has
been added;
[0101] b) add the base(s); of calcined MgO or other alkali earth
oxides or hydroxides by itself or with other bases such as Na or K
to the water and mix dissolved; and
[0102] c) add either the acid or acidic salt (potassium or other
acidic phosphates or ammonium phosphates) to the water and mix it
in until it dissolves.
[0103] It should be noted that by delaying the combination of the
acid and the base as long as possible, all of the total mix time
except step c is added onto the "pot life". When using plastic
additives, the following steps are added to a, b, and c above:
[0104] d) after the acid is added per step (c) and thoroughly mixed
in, add in desired plastic and mix; optionally, catalyst and/or
polymer initiator and/or an emulsifier may be admixed at this time;
or
[0105] e) catalyst and/or polymer initiator is added last and
mixed.
[0106] For Portland cement based mortars, cements and concretes and
for gypsum and aluminum and blended cements, the mixing process is
simplified. The retarders/sequestrants are added to the water first
(although that is not necessary, they can be added to the dry
cement) then water is added and the slurry mixed. Desired plastics
or other additives are mixed in last.
[0107] Color may be added to any of these cementitious sprays,
mortars or concretes at any time during the mix cycle, but with the
phosphate cements colorants are preferentially added as dry mineral
powders or liquid colorants after step (c) above.
[0108] For phosphate cements as premixed powders or for pre-mixed
powders with aggregate, perform step (a) and then add in the water
and mix it.
[0109] Agglomeration is reduced if the acid is added in slowly to
the mixer or hand mixed thereinto, thus lengthening pot life and
yielding a smoother and stronger coating.
[0110] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiment has been shown
and described and that all changes and modifications that come
within the spirit of the invention are to be desired to be
protected.
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