U.S. patent application number 11/269230 was filed with the patent office on 2006-06-15 for process for the stabilization of dusting surfaces.
This patent application is currently assigned to Wacker Polymer Systems Gmbh & Co. KG. Invention is credited to Eric Ferrall, Manfred Selig, Michael Spradling.
Application Number | 20060128839 11/269230 |
Document ID | / |
Family ID | 36096446 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060128839 |
Kind Code |
A1 |
Ferrall; Eric ; et
al. |
June 15, 2006 |
Process for the stabilization of dusting surfaces
Abstract
The invention relates to a process for the stabilization of
dusting surfaces characterized in that the dusty ground is tilled
or scarified and mixed with polymers in form of water-redispersible
polymer powders, which are optionally re-emulsifiably modified, or
reemulsifiable modified aqueous polymer dispersions, which are
optionally sprayed on to the untreated dusty ground. In a preferred
embodiment the redispersible polymer powder, respectively the
reemulsifiable modified redispersible polymer powder or the
reemulsifiable modified aqueous polymer dispersion, is combined
with hydraulically setting compounds, preferably cement and/or
gypsum.
Inventors: |
Ferrall; Eric; (Saline,
MI) ; Spradling; Michael; (Ann Arbor, MI) ;
Selig; Manfred; (Burghausen, DE) |
Correspondence
Address: |
BROOKS KUSHMAN P.C.
1000 TOWN CENTER
TWENTY-SECOND FLOOR
SOUTHFIELD
MI
48075
US
|
Assignee: |
Wacker Polymer Systems Gmbh &
Co. KG
Burghausen
DE
|
Family ID: |
36096446 |
Appl. No.: |
11/269230 |
Filed: |
November 8, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11012647 |
Dec 15, 2004 |
|
|
|
11269230 |
Nov 8, 2005 |
|
|
|
Current U.S.
Class: |
524/5 ; 524/556;
524/571 |
Current CPC
Class: |
C09K 17/16 20130101;
C09K 17/18 20130101; C09K 17/40 20130101; Y10S 106/90 20130101 |
Class at
Publication: |
524/005 ;
524/556; 524/571 |
International
Class: |
C08K 3/00 20060101
C08K003/00; C04B 24/26 20060101 C04B024/26 |
Claims
1. A process for stabilizing a soil surface, comprising treating
soil by means of at least one of a. admixing with soil a
water-redispersible polymer powder or reemulsifiable-modified
redispersible polymer powder to form a soil/polymer mixture and
wetting said soil/polymer mixture to form a polymer-bound soil; or
b. applying to soil an aqueous dispersion of at least one of a
water-redispersible polymer powder or a reemulsifiable-modified
redispersible polymer powder, and optionally compacting the soil
thus treated, with the proviso that the soil surface is free of
water-impermeable polymer film such that the soil is rewettable
with water.
2. The process of claim 1, wherein the soil surface is free of any
water-impermeable polymer film.
3. The process of claim 1, wherein the soil is sand and an aqueous
dispersion of a water-redispersible polymer powder or
remulsifiable-modified redispersible polymer powder is applied to
the soil.
4. The process of claim 1, wherein a water-redispersible polymer
powder or a reemulsifiable-modified redispersible polymer powder is
admixed with soil, and said wetting is accomplished by applying an
aqueous dispersion of a water-redisperesible polymer powder and/or
a reemulsifiable-modified redispersible polymer powder.
5. The process of claim 1, wherein a composition comprising a
water-redispersible polymer powder and a hydraulically settable
cement is admixed with soil and wetted.
6. The process of claim 1, wherein a composition comprising a
reemulsifiable-modified redispersible polymer powder and a
hydraulically settable cement is admixed with soil and wetted.
7. The process of claim 1 wherein said water-redispersible polymer
is a polymer prepared by copolymerizing a monomer mixture
comprising at least one monomer selected from the group consisting
of vinyl esters, (meth)acrylates, vinyl aromatics, olefins,
1,3-dienes, and vinyl halides, in the presence of a protective
colloid.
8. The process of claim 1, wherein said water-redispersible polymer
is a polymer prepared by copolymerizing a monomer mixture
comprising vinyl acetate and ethylene in the presence of a
protective colloid.
9. The process of claim 1 wherein said water-redispersible polymer
is a polymer prepared by copolymerizing a monomer mixture
comprising at least one vinyl ester and an olefin, in the presence
of a protective colloid, and wherein a dispersant is added to the
water-redispersible polymer prior to adding said
water-redisperesible polymer to the soil, or is added to the soil
with the water-redispersible polymer, prior to compaction of the
soil.
10. The process of claim 1, wherein said water-redispersible
polymer is a polymer prepared by copolymerizing a monomer mixture
comprising vinyl acetate and ethylene in the presence of a
protective colloid, and wherein a dispersant is added to the
water-redispersible polymer prior to adding said
water-redisperesible polymer to the soil, or is added to the soil
with the water-redispersible polymer, prior to compaction of the
soil.
11. The process of claim 1, wherein the soil is compacted in a
moist state.
12. The process of claim 2, wherein the soil is compacted in a
moist state.
13. A process for restabilizing stablized soil prepared by the
process of claim 1, comprising rewetting the soil.
14. The process of claim 13, wherein the soil is tilled or
scarified prior to, during, or following rewetting, and is
subsequently compacted.
15. A stabilized soil, prepared by the process of claim 1, having a
hard surface permeable to water.
16. A stabilized soil, prepared by the process of claim 2, having a
hard surface permeable to water.
17. A stabilized soil, prepared by the process of claim 3, having a
hard surface permeable to water.
18. A stabilized soil, prepared by the process of claim 4, having a
hard surface permeable to water.
19. A stabilized soil, prepared by the process of claim 5, having a
hard surface permeable to water vapor.
20. A stabilized soil, prepared by the process of claim 6, having a
hard surface permeable to water vapor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 11/012,647,filed Dec. 15, 2004.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a process for the stabilization of
dusting surfaces with polymers in form of water-redispersible
polymer powders, which are optionally reemulsifiable modified, or
reemulsifiable modified aqueous polymer dispersions.
[0004] 2. Background Art
[0005] Dust control and soil stabilization is a major environmental
and health issue. Dust, for example road dust of unpaved roads and
gravel roads, pollutes the environment and poses health risks. Soil
stabilization retards both wind and water erosion. Furthermore the
condition of roads is an important part of road safety. It is
improved by the stabilization of unpaved roads preventing the
development of ruts, bumps and washboards. Fine particle
stabilization also has significant economic advantages in extending
the working lives of such machinery as air heating and cooling
units and turbine engines. In general dust is composed of fine
particles with a particle size of 1 .mu.m to 2 mm.
[0006] For soil stabilization it has been the state of art to spray
mineral oil products onto the surface of unpaved roads with all the
environmental disadvantages. Water-dilatable binders like calcium
chloride solutions and lignosulfonate solutions have also been used
for dust control and surface stabilization. JP-B 05-53881, ZA-A
8803253, and JP-B 49046716 concern surface stabilization with
conventional aqueous polymer dispersions. Aqueous polymer
solutions, e.g. solutions of polyacrylic acid have been used to
control dust on gravel roads. The major problem of water based
polymer products is that 1) they only bind dusting particles a
single time because they do not redisperse, 2) they are slow to dry
and form films due to the water necessary to apply the dispersions
and 3) they are more difficult to till or scarify into the material
being bound due to their inherent liquid state. Therefore every
half year these compounds have to be applied again. When used in
deep reaching applications (i.e. depths of more than one inch) to
improve durability, water based products show the additional
disadvantage of drying much too slowly, which leads to prohibitive
closure times of the road. Considering the above mentioned rate of
erosion and the subsequent frequent rate of application, the state
of the art is not only economically disadvantageous but also
environmentally questionable considering the biodegradability and
the chemical nature of most monomer bases now in use for this type
of application.
[0007] U.S. Pat. No. 3,736,758 discloses a process for rendering
soil at chemical storage sites impervious to liquids, by adding a
conventional polymer dispersion to a depth of soil, moistening and
compacting the soil, and applying an impermeable thick film or
coating of an organic polymer over the treated and compacted soil
to render the surface impermeable. The process is expensive due to
the amount of impermeable polymer added onto the surface, and for
many such polymers requires an organic solvent which is
environmentally undesirable. If the integrity of the stabilized
soil is compromised, the soil cannot be again stabilized without
removing the impermeable coating and adding additional polymer
dispersion.
SUMMARY OF THE INVENTION
[0008] It was thus an object of the invention to provide a process
for soil stabilization of dusting surfaces which avoids
environmental disadvantages, and which does not need a complete
renewal of the surface treatment in short time cycles. These and
other objects are achieved by a process for the stabilization of
dusting surfaces, characterized in that the dusty ground is tilled
or scarified and mixed with polymers in the form of
water-redispersible polymer powders, which are optionally
reemulsifiable modified, or reemulsifiable modified aqueous polymer
dispersions, which are optionally sprayed on to the untreated dusty
ground.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0009] Redispersible polymer powders are characterized in that they
are readily redispersible after stirring with water, largely
breaking down into the original particles of the initial
dispersions, and forming water resistant polymer films.
Redispersible reemulsifiable modified polymer powders are
redispersible polymer powders that are modified by the addition of
an amount of dispersant which causes controlled partial
reemulsification of the polymer film on exposure to sufficient
moisture. Reemulsifiable modified polymer dispersions, in contrast
to common polymer dispersions which build up water-resistant
polymer films, contain an additional amount of dispersant which
causes controlled reemulsification of the first obtained polymer
film after further contact with water. In general, reemulsifiable
modified polymer powders or reemulsifiable modified aqueous polymer
dispersions mean that a polymer film resulting from application of
the polymer or polymer dispersion will begin reemulsifying
(breaking down) immediately on exposure to water under normal
conditions to a degree of at least 50% by weight, preferably of at
least 90% by weight. The polymers are based on one or more monomers
from the group consisting of vinyl esters, (meth)acrylates, vinyl
aromatics, olefins, 1,3-dienes and vinyl halides and, if required,
further monomers copolymerizable therewith.
[0010] Suitable vinyl esters are those of carboxylic acids having 1
to 12 C atoms. Vinyl acetate, vinyl propionate, vinyl butyrate,
vinyl 2-ethylhexanoate, vinyl laureate, 1-methylvinyl acetate,
vinyl pivalate and vinyl esters of .alpha.-branched monocarboxylic
acids having 9 to 11 C atoms, for example VeoVa9.sup.R or
VeoVa10.sup.R (trade names of Resolution Performance Products), are
preferred. Vinyl acetate is particularly preferred.
[0011] Suitable acrylate and methacrylate monomers include esters
of straight-chain or branched alcohols having 1 to 15 carbon atoms.
Preferred methacrylates or acrylates are methyl acrylate, methyl
methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate,
propyl methacrylate, n-butyl acrylate, n-butyl methacrylate,
tert-butyl acrylate, tert-butyl methacrylate and 2-ethylhexyl
acrylate. Methyl acrylate, methyl methacrylate, n-butyl acrylate,
tert-butyl acrylate and 2-ethylhexyl acrylate are particularly
preferred. Preferred vinyl aromatics are styrene, methylstyrene and
vinyltoluene. A preferred vinyl halide is vinyl chloride. The
preferred olefins are ethylene and propylene, and the preferred
dienes are 1,3-butadiene and isoprene.
[0012] If required, 0.1 to 5% by weight, based on the total weight
of the copolymer, of auxiliary monomers may also be copolymerized.
Preferably, 0.5 to 2.5% by weight of auxiliary monomers is used.
Examples of auxiliary monomers are ethylenically unsaturated mono-
and dicarboxylic acids, preferably acrylic acid, methacrylic acid;
ethylenically unsaturated carboxamides and carbonitriles,
preferably acrylamide and acrylonitrile; and ethylenically
unsaturated sulfonic acids and their salts, preferably vinyl
sulfonic acid and 2-acrylamido-2-methylpropane sulfonic acid.
Further examples are precrosslinking co-monomers such as
polyethylenically unsaturated comonomers, for example divinyl
adipate or triallyl cyanurate, or postcrosslinking comonomers, for
example N-methylolacrylamide (NMA), N-methylol-methacrylamide,
alkyl ethers, such as the isobutoxy ether, or esters, of
N-methylolacrylamide. Comonomers having epoxide functional groups,
such as glycidyl methacrylate and glycidyl acrylate, are also
suitable. Further examples are comonomers having silicon functional
groups, such as (meth)acryloyloxypropyltri(alkoxy)silanes,
vinyltrialkoxysilanes and vinylmethyldialkoxysilanes.
[0013] The choice of monomers or the choice of the amounts by
weight of the comonomers is made in such a way that in general a
glass transition temperature Tg of -50.degree. C. to +50.degree.
C., preferably -30.degree. C. to +40.degree. C., most preferably -5
to 15.degree. C., results. The glass transition temperature Tg of
the polymer can be determined in a known manner by means of
differential scanning calorimetry (DSC). The Tg can also be
calculated approximately beforehand using the Fox equation.
According to T. G. Fox, BULL. AM. PHYSICS Soc. 1, 3, page 123
(1956), the following is applicable:
1/Tg=x.sub.1/Tg.sub.1+x.sub.2/Tg.sub.2 + . . . + x.sub.n/Tg.sub.n,
where x.sub.n is the mass fraction (% by weight/100) of the monomer
n and Tg.sub.n is the glass transition temperature in Kelvin of the
homopolymer of the monomer n. Tg values for homopolymers appear in
Polymer Handbook, 2nd Edition, J. Wiley & Sons, New York
(1975).
[0014] Particularly preferred are homopolymers and copolymers of
vinyl ester monomers, particularly vinyl acetate. Most preferred
are polyvinyl acetate, copolymers of vinyl acetate and ethylene,
copolymers comprising vinyl acetate, ethylene and a vinylester(s)
of a-branched monocarboxylic acids having 9 to 11 C atoms. It being
possible for said polymers also to contain, if required, one or
more of the abovementioned auxiliary monomers.
[0015] The polymers are prepared in a manner known per se by the
emulsion polymerisation process or by the suspension polymerisation
process, preferably by the emulsion polymerisation process, the
polymerisation temperature being in general 40.degree. C. to
100.degree. C., preferably 45.degree. C. to 90.degree. C. In the
copolymerisation of gaseous comonomers such as ethylene,
1-3-butadiene or vinyl chloride, superatmospheric pressure, in
general from 5 bar to 100 bar, may also be employed.
[0016] The polymerisation is initiated with the water-soluble or
monomer-soluble initiators or redox initiator combinations
customarily used for emulsion polymerisation or suspension
polymerisation. In a preferred embodiment the monomers are
stabilized by protective colloids.
[0017] Suitable protective colloids are polyvinyl alcohols;
polyvinylpyrrolidones; polyvinyl acetals; polysaccharides in
water-soluble form, such as starches (amylose and amylopectin),
celluloses and their carboxymethyl, methyl, hydroxyethyl and
hydroxypropyl derivatives; proteins, such as casein or caseinate,
soybean protein and gelatin; ligninsulfonates; synthetic polymers,
such as (meth)acrylic acid, copolymers of (meth)acrylates with
comonomer units having carboxyl functional groups,
poly(meth)acrylamide, polyvinylsulfonic acids and their
water-soluble copolymers; melamine formaldehyde sulfonates,
naphthalene formaldehyde sulfonates and styrene maleic acid and
vinyl ether/maleic acid copolymers. Partially hydrolysed or
completely hydrolysed polyvinyl alcohols are preferred. The
protective colloids are generally added in a total amount of 1 to
20% by weight, based on the total weight of the monomers, during
the polymerisation.
[0018] It may be advantageous additionally to use small amounts of
emulsifiers if desired, for example 1 to 5% by weight, based on the
amount of monomers. Suitable emulsifiers are anionic, cationic and
non-ionic emulsifiers, for example anionic surfactants, such as
alkylsulfates having a chain length of 8 to 18 C atoms, alkyl or
alkylaryl ether sulphates having 8 to 18 C atoms in the hydrophobic
radical and up to 40 ethylene oxide or propylene oxide units,
alkane- or alkylarylsulfonates having 8 to 18 C atoms, esters and
monoesters of sulfosuccinic acid with monohydric alcohols or
alkylphenols, or nonionic surfactants, such as alkyl polyglycol
ethers or alkylaryl polyglycol ethers having 8 to 40 oxyetehylene
units therein.
[0019] The thus obtained initial polymer dispersions have a solids
content of 30 to 70%, and may be diluted for further processing or
final application. For the preparation of the water-redispersible
polymer powders, the aqueous dispersions are spray-dried after the
addition of protective colloids as spraying assistants.
[0020] As a rule, the spraying assistant is used in a total amount
of 3 to 30% by weight, based on the polymeric components of the
dispersion. This means that the total amount of the protective
colloid before the drying process should be at least 3 to 30% by
weight, based on the polymer fraction; preferably, 5 to 20% by
weight, based on the polymer fraction, are used. Suitable spraying
assistants are partially hydrolysed polyvinyl alcohols;
polyvinylpyrrolidones; polysaccharides in water-soluble form such
as starches (amylose and amylopectin), celluloses and their
carboxymethyl, methyl, hydroxyethyl and hydroxypropyl derivatives;
proteins such as casein or caseinate, soybean protein, gelatin;
ligninsulfonates; synthetic polymers such as poly(meth)acrylic
acid, copolymers of (meth)acrylates with co monomer units having
carboxyl functional groups, poly(meth)acrylamide, polyvinylsulfonic
acids and their water-soluble copolymers; melamine formaldehyde
sulfonates, naphthalene formaldehyde sulfonates and styrene/maleic
acid and vinyl ether-/maleic acid copolymers.
[0021] The rebuilding mechanism can be enhanced by the combination
of the water-redispersible polymer powders with dispersants, to
obtain reemulsifiable modified water-redispersible polymer powders.
This type of polymer powder facilitates the redispersion of the
polymer powder after contact with water. Common dispersants are the
protective colloids and emulsifiers already mentioned above.
Preferred emulsifiers are based on ethoxylated fatty alcohols. The
preferred dosage of additional dispersant is 1 to 20% based on the
total weight percent of redispersible polymer powder used. These
additional components for application and performance control may
be added either during the stage of polymerization, the stage of
spray drying or as a post add, the latter being preferred.
[0022] In the case of the reemulsifiable modified aqueous polymer
dispersions, dispersants are added after the preparation of the
polymer dispersion. Common dispersants are the protective colloids
and emulsifiers already mentioned above. Preferred emulsifiers are
based on ethoxylated fatty alcohols. The preferred dosage of
dispersant is 1 to 20% based on the total weight percent of the
polymer dispersion used.
[0023] In a further preferred embodiment the redispersible polymer
powder, and more preferably the reemulsifiable modified
redispersible polymer powder or the reemulsifiable modified aqueous
polymer dispersion, is combined with hydraulically setting
compounds, preferably cement and/or gypsum. With this combination
an improvement of the drying time is achieved, and redispersion of
compositions containing hydraulically setting compounds is aided as
well.
[0024] The process is suitable for the soil stabilisation and dust
binding of various undergrounds: Unpaved dirt roads, forestry
roads, agricultural access roads, road shoulders, road bed
sub-base, construction sites, land development, slopes, and dumps,
coal piles, seasonal roads, private roads and driveways, parking
lots, airstrips, athletic fields, landing pads, public parks, and
athletic fields. Usually the underground is tilled or scarified to
a depth of 1 to 500 mm, preferably 50 to 150 mm, and the loose
material is admixed with the polymer powder or the polymer
dispersion. Preferably 0.01 to 5% b.w. polymer solids, particulary
0.2 to 2.0% b. w. polymer solids, of polymer powder or polymer
dispersion, based on the soil material to be stabilized, is used.
In general, the thus prepared underground is then levelled and
compacted or graded. Alternativly polymer dispersions can be
sprayed onto the untreated underground.
[0025] For the activation of binding of the underground it only
needs to be exposed to moisture, preferably by spraying with water,
whereupon film-forming of the water-redispersible polymer powder
occurs. Redispersable powders, especially with additional
dispersant(s) (reemulsifiable modified), have unique performance
properties superior to the state of the art: With every rainfall,
the film fibers will desintegrate to a controlled extent allowing a
refilming process to start in the next drying cycle. Thus any newly
formed dust particles will be trapped, with film-forming occuring
as deep as the water penetrates into the material and as deep as
the polymer powder is admixed with the loose dirt material. For
these reasons, in contrast to the soil stabilization by spraying
the underground with common polymer dispersions which build strong
films but without any rebinding capacity, the claimed polymer film
is rebuilt again and again after contact with moisture.
Additionally dust binding occurs as deep as the dust is admixed
with polymer powder. With common aqueous polymer dispersions,
binding of dust particles only occurs on the initial application
and proper film formation of the polymer only occurs near the
application surface where sufficient drying can occur by
evaporation.
[0026] In the case of reemulsifiable modified polymer dispersions,
no strong water-resistant polymer films occur as is the case with
common polymer dispersions. After rainfall or after spraying with
water following a longer dry period, the polymer film disintegrates
and is rebuilt again and again, and additional dust binding occurs
in a similar mechanism as already described above for redispersible
polymer powders.
[0027] With cementitious materials added, further improvement to
the state of the art occurs as a result of a drying mechanism in
addition to evaporation. Cementitious materials may be added in
amounts of less than 1% by weight to 20% by weight, preferably 1%
to 10%, and most preferably about 1% to 4% by weight, relative to
the weight of soil to be bound. As is the case with common aqueous
dispersions, proper film formation below the surface of an
application, whether initially sprayed onto the surface or tilled
into the ground, may never occur, and then only over very long
periods of time. With the addition of cementitious materials,
drying occurs below the surface via chemical consumption of the
water, whether a polymer powder or an aqueous dispersion is
applied, to support proper film formation regardless of the
localized evaporation rate at varying depths.
[0028] The soil thus stabilized may, in general, be quite hard,
similar upon visual inspection in the case of sand or sandy soils,
to the appearance of cements or mortars. The soil thus stabilized
also possesses considerable tensile strength and modulus, and
depending upon the depth of soil treated and the amount of treating
agent, may support considerable loads. Should the upper level
crack, be pulverized with heavy machinery, or have additional soil
or dust deposited thereon, the soil may be wetted and again
compacted, renewing the stabilization of the soil. While a strongly
stabilized soil is thus obtained, the soil remains permeable to
water.
[0029] Because it is desirable for the soil to be able to be
restabilized by addition of moisture, whether purposefully added or
as a result of natural precipitation, it is most desirable that the
surface remain free of impermeable films and vapor barriers,
whether applied in situ, for example by spraying a non-foaming
polyurethane or other thermoset polymer layer, or by coverage with
a plastics film. Thus, the process of the invention preferably does
not employ the addition of any water impermeable film, and in
particular, any polymer film of sufficient integrity and
imperviousness such that a relatively uniform rewetting of the soil
is prevented. It would not depart from the spirit of the invention,
however, to spray onto the treated area a very thin film of a water
impermeable substance uniformly or over portions, wherein the
thickness or the areal discontinuities or both are such that
rewetting of the soil can in fact readily take place, preferably
without scarifying or reworking of the soil. Such films are, in
general, less than 0.1 mm in thickness, and are themselves
preferably formed of an aqueous polymer dispersion, but not of a
polymer which is water redispersible. Coatings of thermoset,
crosslinked polymers such as polyurethanes, epoxy resins, vinyl
ester resins, and the like are in particular preferably avoided.
Even without such coatings, a hard, stabilized soil is produced,
which, in the case of use of redispersible polymers alone is at
least somewhat water permeable, and in the case where cementitious
ingredients are also added, is water vapour permeable, which is not
the case when films such as polyurethanes or epoxy resins are
applied to the surface.
[0030] The tests below serve as a further illustration of the
invention:
[0031] For the test of soil stabilization, dirt was obtained from
two different Michigan dirt roads that represent the primary target
for such an application. The dirt collected was characterized
before testing began with the following results: TABLE-US-00001
Sieve Size Percent Retained Particle Size Analysis of MI Dirt 16
44.4 30 15.4 50 19.1 70 7.4 100 5.2 200 4.4 Pan 4.2 Physical
Properties of MI Dirt Avg Water Content 3.48% Avg Wet Density 1.92
g/ml Avg Dry Density 1.79 g/ml
Testing of soil stabilisation:
COMPARISON EXAMPLE 1
[0032] 250 g of MI dirt was weighed into a cup.
[0033] For testing a state of art dust binding composition, 4.7 g
of a polyacrylate dispersion (solids content 47%) and 9 g of water
were mixed into the dirt until uniform wet-out appeared to have
been achieved. The cup was then placed in an oven at 50.degree. C.
to accelerate drying. After 12 hours the cup was removed from the
oven and was subjectively evaluated for binding of the dust by
shaking the cup and observe the mass of particles that is
emitted.
COMPARISON EXAMPLE 2
[0034] According to comparison example 1, but instead of 4.7 g of
the polymer dispersion, 15 g of water was mixed with the dust. The
cup was then placed in an oven at 50.degree. C. to accelerate
drying. After 12 hours the cup was removed from the oven and was
subjectively evaluated for binding of the dust by shaking the cup
and observe the mass of particles that is emitted.
EXAMPLE 3
[0035] According to comparison example 1, but instead of 4.7 g of
the polymer dispersion, 5 g of a redispersible polymer powder based
on a vinyl acetate-ethylene copolymer was mixed with a metal
spatula into the dirt until it seemed homogenous. Then 15 g of
water was added to the homogenous mixture and mixed in. The cup was
then placed in an oven at 50.degree. C. to accelerate drying. After
12 hours the cup was removed from the oven and was subjectively
evaluated for binding of the dust by shaking the cup and observe
the mass of particles that is emitted.
EXAMPLE 4
[0036] According to comparison example 1, but instead of 4.7 g of
the polymer dispersion, 1.5 g of a redispersible polymer powder
based on a vinyl acetate-ethylene copolymer, and 3 g of
cementitious material was mixed with a metal spatula into the dirt
until it seemed homogenous. Then 15 g of water was added to the
homogenous mixture and mixed in. The cup was then placed in an oven
at 50.degree. C. to accelerate drying. After 12 hours the cup was
removed from the oven and was subjectively evaluated for binding of
the dust by shaking the cup and observe the mass of particles that
is emitted.
EXAMPLE 5
[0037] Unlike comparison example 1, 1000 g of MI dirt was
introduced into a one liter beaker. To the beaker was added 10 g of
a redispersible polymer powder based on a vinyl acetate-ethylene
copolymer, and 2.5 g of an ethoxylated fatty alcohol was mixed with
a metal spatula into the dirt until it seemed homogenous. Then 15 g
of water was added to the homogenous mixture. The beaker was then
placed in an oven at 50.degree. C. to accelerate drying. After 12
hours the beaker was removed from the oven and was subjectively
evaluated for binding of the dust by shaking the cup and observe
the mass of particles that is emitted.
[0038] The bound layer of dirt at the top of each beaker was then
removed, physically crushed to a similar particle size as the
original MI dirt, was mixed with 5% by weight of the homogeneous
mixture from its respective beaker (to simulate mixing that would
occur in an actual application), and was added back to the beaker.
15 g of water was then added to the top of the beaker, and the was
placed back in the oven at 50.degree. C. to accelerate drying.
After 12 hours, the beaker was removed from the oven and was
subjectively evaluate for binding of the dust by shaking the beaker
and observing the mass of particles that was emitted.
EXAMPLE 6
[0039] According to example 5, but in addition to the redispersible
polymer powder and to the ethoxylated fatty alcohol 20 g of
cementitious material was mixed with a metal spatula into the dirt
until it seemed homogenous. Then 15 g of water was added to the top
of the beaker. The cup was then placed in an oven at 50.degree. C.
to accelerate drying. After 12 hours the cup was removed from the
oven and was subjectively evaluated for binding of the dust by
shaking the cup and observe the mass of particles that is
emitted.
[0040] The bound layer of dirt at the top of each beaker was then
removed, physically crushed to a similar particle size as the
original MI dirt, was mixed with 5% by weight of the homogeneous
mixture from its respective beaker (to simulate mixing that would
occur in an actual application), and was added back to the beaker.
15 g of water was then added to the top of the beaker, and the was
placed back in the oven at 50.degree. C. to accelerate drying.
After 12 hours, the beaker was removed from the oven and was
subjectively evaluate for binding of the dust by shaking the beaker
and observing the mass of particles that was emitted.
Test Results:
[0041] The results were rated as follows: [0042] 3=Very good dust
binding, better than state of the art [0043] 2=Good dust binding,
similar to the state of the art [0044] 1=Low dust binding
[0045] 0=No dust binding TABLE-US-00002 TABLE 1 Cycle/ Comp. Comp.
Example Example Example Comp. Sample Ex. 1 Ex. 2 3 4 5 Ex. 6 First
2 1 3 2 2.5 3 Second -- -- -- -- 2.5 3
* * * * *