U.S. patent application number 16/708524 was filed with the patent office on 2021-01-07 for producing cementitious materials with improved hydrophobicity and strength using reclaimed waste substances.
This patent application is currently assigned to AllNew Chemical Technology Company. The applicant listed for this patent is Chi-Yao Chen, Fu-Ming Lee, John Lee, Maw-Tien Lee, Zih-Yao Shen. Invention is credited to Chi-Yao Chen, Fu-Ming Lee, John Lee, Maw-Tien Lee, Zih-Yao Shen.
Application Number | 20210002173 16/708524 |
Document ID | / |
Family ID | |
Filed Date | 2021-01-07 |
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United States Patent
Application |
20210002173 |
Kind Code |
A1 |
Lee; Maw-Tien ; et
al. |
January 7, 2021 |
Producing Cementitious Materials with Improved Hydrophobicity and
Strength Using Reclaimed Waste Substances
Abstract
A hydrophobic admixture, for cementitious materials such as
cement paste, mortar, and concrete, includes solid polymer
particles with a coating of hydrophobic agent and surfactant. The
solid polymer particles adhere to exterior surfaces of hydrated
cement particles in the cement matrix. The solid polymer particles
deliver the hydrophobic agent into the cement matrix which is
hydrophilic. The hydrophobic agents are distributed uniformly
throughout the cement matrix. The solid polymer particles can be
crumb rubber particles derived from waste rubber tires, recycled
plastics and similar solid materials. The hydrophobic liquid agent
is derived from waste lubricant oil, spent motor oil, base oil,
esters of fatty acids, vegetable oil and the like. Fine particles
such as activated carbon, silica fume and spent catalyst can be
employed to fill the large pores or cracks that develop in the
cementitious matrix. The cured cementitious materials exhibit high
contact angles and high compressive strengths.
Inventors: |
Lee; Maw-Tien; (Taipei,
TW) ; Shen; Zih-Yao; (Taipei, TW) ; Chen;
Chi-Yao; (Taipei, TW) ; Lee; Fu-Ming; (Katy,
TX) ; Lee; John; (Taipei, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lee; Maw-Tien
Shen; Zih-Yao
Chen; Chi-Yao
Lee; Fu-Ming
Lee; John |
Taipei
Taipei
Taipei
Katy
Taipei |
TX |
TW
TW
TW
US
TW |
|
|
Assignee: |
AllNew Chemical Technology
Company
Taipei
TW
|
Appl. No.: |
16/708524 |
Filed: |
December 10, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16458771 |
Jul 1, 2019 |
10590038 |
|
|
16708524 |
|
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Current U.S.
Class: |
1/1 |
International
Class: |
C04B 14/02 20060101
C04B014/02; C04B 18/04 20060101 C04B018/04; C04B 18/14 20060101
C04B018/14; C04B 18/22 20060101 C04B018/22 |
Claims
1. A set cementitious composition, that comprises cement paste,
mortar, or concrete, and which comprises a cement mixture with
hydrated cement particles dispersed therein and which comprises
solid polymer particles that have a surface coating comprising a
hydrophobic agent, wherein the solid polymer particles adhere to
exterior surfaces of the hydrated cement particles, (ii) a
surfactant that is blended with the hydrophobic agent and (iii)
fine particles that are selected from the group consisting of
activated carbon, silica fume, spent catalyst, and mixtures thereof
and that fill pores or cracks in the composition.
2. (canceled)
3. The set cementitious composition of claim 1 wherein the
composition has an exterior surface which has a contact angle of at
least 45 degrees.
4. The set cementitious composition of claim 1 wherein the
composition has a compressive strength of at least 15 to 50
MPa.
5. The set cementitious composition of claim 1 wherein the cement
mixture is prepared from a cementitious material, water, and a
hydrophobic admixture comprising coated solid polymer particles
comprising solid polymer particles that are coated with the
hydrophobic agent, wherein the coated solid polymer particles are
mixed with the cementitious material in a weight ratio from 1:1 to
1:100.
6. The set cementitious composition of claim 5 wherein the weight
ratio from 1:1 to 1:10.
7. (canceled)
8. (canceled)
9. The set cementitious composition of claim 1 wherein the solid
polymer particles comprise crumb rubber particles, the hydrophobic
agent is selected from the group consisting of waste lubricant oil,
spent motor oil, base oil, ester of fatty acids, vegetable oil, and
mixtures thereof, the fine particles are selected from the group
consisting of activated carbon, silica fume, spent catalyst, and
mixtures thereof
10. (canceled)
11. A method of preparing a cementitious composition which
comprises (a) forming a cement mixture by mixing dry cement, water,
and a hydrophobic admixture which comprises solid polymer particles
that have a surface coating comprising (i) a hydrophobic agent
whereby the solid polymer particles adhere to exterior surfaces of
hydrated cement particles that develop in the cement mixture, (ii)
a surfactant that is blended with the hydrophobic agent and (iii)
fine particles; and (b) curing the cement mixture to form a set
cementitious composition wherein the solid polymer particles
comprise crumb rubber particles, the hydrophobic agent is selected
from the group consisting of waste lubricant oil, spent motor oil,
base oil, ester of fatty acids, vegetable oil, and mixtures
thereof, the fine particles are selected from the group consisting
of activated carbon, silica fume, spent catalyst, and mixtures
thereof and the fine particles fill pores or cracks in the set
cementitious composition.
12. The method of claim 11 wherein the cementitious composition
comprises cement paste, mortar, or concrete.
13. The method of claim 11 wherein the set cementitious composition
has an exterior surface which has a contact angle of at least 45
degrees.
14. The method of claim 11 wherein the set cementitious composition
has a compressive strength of 15 to 50 MPa.
15. The method of claim 11 wherein the hydrophobic admixture is
mixed with the cement in a weight ratio from 1:1 to 1:100.
16. The method of claim 15 wherein the weight ratio from 1:1 to
1:10.
17-20. (canceled)
21. The method of claim 11 wherein the hydrophobic admixture is
prepared by (i) mixing the hydrophobic agent and surfactant to form
a modified hydrophobic agent, (ii) mixing the solid polymer
particles with the modified hydrophobic agent to form coated solid
polymer particles and (iii) blending the fines particles into the
coated solid polymer particles.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional application of U.S. patent
application Ser. No. 16/458,771, that was filed on Jul. 1,
2019.
FIELD OF THE INVENTION
[0002] The present invention relates to hydrophobic admixtures for
cementitious materials and more particularly to admixtures, which
are formed from (i) crumb rubber which is derived from waste rubber
tires and plastics, (ii) waste lubricant oil and the like, (iii)
surfactant, and (iv) fine particles, that impart water repellant
properties without compromising the cementitious materials'
mechanical strength.
BACKGROUND OF THE INVENTION
[0003] A cementitious mixture refers to pastes, mortars, and
concrete compositions comprising a hydraulic cement binder having
consistencies ranging from stiff to extremely dry. Pastes are
defined as mixtures composed of a hydraulic cement binder, either
alone or in combination with pozzolans such as fly ash, silica
fume, or blast furnace slag, and water. Mortars are defined as
pastes that additionally include fine aggregate. Concretes
additionally include coarse aggregate. These compositions may
additionally include other admixtures such as set retarders, set
accelerators, defoaming agents, air-entraining or air detraining
agents, corrosion inhibitors, water reducing agents, and
pigments.
[0004] Water repellant components have also been incorporated into
conventional cement mixtures but the hydrophobic cementitious
mixtures that are produced tend to exhibit reduced mechanical
strengths. In addition, most hydrophobic agents are lipophilic
organic solvents whereas the cement matrix is hydrophilic. The
hydrophobic agents are insoluble in the water phase, causing
inhomogeneous dispersion of the hydrophobic agent in aqueous
cementitious mixtures. Industry is in need of developing improved
hydrophobic cementitious mixtures using low-cost additives
particularly from reclaimed waste materials.
SUMMARY OF THE INVENTION
[0005] The present invention is based in part on the development of
an admixture comprising of (i) crumb rubber particles which are
preferably derived from waste rubber tires, recycled plastics and
similar solid materials and (ii) a hydrophobic liquid agent that is
preferably derived from waste lubricant oil, spent motor oil, base
oil, esters of fatty acids, vegetable oil and the like. The crumb
rubber particles serve as solid polymer carriers for the
hydrophobic agent. The admixture is incorporated into cementitious
mixtures or materials to enhance their hydrophobicity without
reducing their strengths. A surfactant can be blended into the
hydrophobic agent to form a modified hydrophobic agent. The
surfactant improves the surface property of the carrier particles.
The hydrophobic admixture can also include fine particles, which
are non-polymeric (non-rubber and non-plastic) solid particles,
such as, for instance, activated carbon, silica fume, and spent
catalyst. The fine particles fill the large pores or cracks that
develop in the cementitious matrix to increase the mechanical
strength of the cementitious material. The cured or set
cementitious materials that are formed, including cement paste,
mortar, and concrete, exhibit high contact angles and high
compressive strengths.
[0006] In one aspect, the invention is directed to an admixture
composition, for improving the hydrophobicity of a cementitious
material that includes a cement mixture with hydrated cement
particles dispersed therein, which comprises solid polymer
particles that have a surface coating comprising a hydrophobic
agent, wherein the solid polymer particles adhere to exterior
surfaces of the hydrated cement particles, and at least one of (i)
a surfactant that is blended with the hydrophobic agent or (ii)
fine particles.
[0007] In another aspect, the invention is directed to a set
cementitious composition which includes a cement mixture with
hydrated cement particles dispersed therein and which comprises
solid polymer particles that have a surface coating comprising a
hydrophobic agent, wherein the solid polymer particles adhere to
exterior surfaces of the hydrated cement particles, and at least
one of (i) a surfactant that is blended with the hydrophobic agent
or (ii) fine particles.
[0008] In yet another aspect, the invention is directed to a method
of preparing a cementitious composition which includes (a) forming
a cement mixture by mixing dry cement, water, and a hydrophobic
admixture which comprises solid polymer particles that have a
surface coating comprising a hydrophobic agent whereby the solid
polymer particles adhere to exterior surfaces of hydrated cement
particles that develop in the cement mixture, and at least one of
(i) a surfactant that is blended with the hydrophobic agent or (ii)
fine particles; and (b) curing the cement mixture to form a set
cementitious composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIGS. 1A, 1B, 1C and 1D are schematics that depict treated
hydrophobic carriers homogeneously distributed in an aqueous
cementitious mixture;
[0010] FIGS. 2A, 2B, and 2C are photographic views of cement paste
samples with hydrophobic admixtures of rubber particles, lubricant
oil (without any surfactant), and activated carbon;
[0011] FIGS. 3A, 3B, and 3C are photographic views of cement paste
samples with hydrophobic admixtures of rubber particles, lubricant
oil, SPAN 20, and activated carbon;
[0012] FIGS. 4A, 4B, and 4C are photographic views of cement paste
samples with hydrophobic admixtures of rubber particles, lubricant
oil, SPAN 80, and activated carbon;
[0013] FIGS. 5A and 5B are photographic views of mortar specimens
incorporating a hydrophobic admixture of (i) rubber mixture
containing 40 wt % crumb rubber particles, no lubricant oil, and 60
wt % activated carbon and (ii) no SPAN 20 surfactants;
[0014] FIG. 6 is a photographic view of a mortar specimen
incorporating a hydrophobic admixture of 35 wt % crumb rubber
particles, 5 wt % lubricant oil and SPAN 20 blend, and 60 wt %
activated carbon, wherein the surfactant to lubricant oil weight
ratio is 3:7;
[0015] FIGS. 7A and 7B are photographic views of mortar specimens
incorporating a hydrophobic admixture of 52.2 wt % crumb rubber
particles, 7.8 wt % lubricant oil and SPAN 20 blend, and 40 wt %
activated carbon and (ii) surfactant, wherein the surfactant to
lubricant oil weight ratio is 3:7;
[0016] FIGS. 8A and 8B are photographic views of mortar specimens
incorporating a hydrophobic admixture of 41.7 wt % crumb rubber
particles, 8.3 wt % lubricant oil and SPAN 20 blend, and 50 wt %
activated carbon, wherein the surfactant to lubricant oil weight
ratio is 3:7;
[0017] FIGS. 9A and 9B are photographic views of mortar specimens
incorporating a hydrophobic admixture of 32 wt % crumb rubber
particles, 8 wt % lubricant oil and SPAN 20 blend, and 60 wt %
activated carbon, wherein the surfactant to lubricant oil weight
ratio is 3:7;
[0018] FIG. 10 is a photographic view of a mortar specimen
incorporating a hydrophobic admixture of 30 wt % crumb rubber
particles, 10 wt % lubricant oil and SPAN 20 blend, and 60 wt %
activated carbon, wherein the surfactant to lubricant oil weight
ratio is 3:7;
[0019] FIGS. 11A and 11B are photographic views of mortar specimens
incorporating a hydrophobic admixture of 25 wt % crumb rubber
particles, 15 wt % lubricant oil and SPAN 20 blend, and 60 wt %
activated carbon, wherein the surfactant to lubricant oil weight
ratio is 3:7;
[0020] FIG. 12 is a photographic view of a mortar specimen
incorporating a hydrophobic admixture of 15 wt % crumb rubber
particles, 15 wt % lubricant oil and SPAN 20 blend, and 70 wt %
activated carbon, wherein the surfactant to lubricant oil weight
ratio is 3:7;
[0021] FIG. 13 is a photographic view of a mortar specimen
incorporating a hydrophobic admixture of 5 wt % crumb rubber
particles, 15 wt % lubricant oil and SPAN 20 blend, and 80 wt %
activated carbon, wherein the surfactant to lubricant oil weight
ratio is 3:7;
[0022] FIGS. 14A, 14B, 14C, and 14D are photographic views of
mortar specimens incorporating a hydrophobic admixture of 35 wt %
crumb rubber particles, 5 wt % oil and SPAN 20 blend, and 60 wt %
activated carbon, wherein the surfactant to lubricant oil weight
ratio is 3:7 and the oil consisted of spent lubrication oil, used
motor oil, castor oil, and caprylic/capric triglyceride,
respectively;
[0023] FIGS. 15A, 15B, 15C, 15D, 15E, 15F, 15G, 15H, and 15I are
photographic views of mortar specimens incorporating a hydrophobic
admixture of 30 wt % crumb rubber particles, 10 wt % oil and SPAN
20 blend, and 60 wt % activated carbon, wherein the surfactant to
oil weight ratio is 3:7 and the oil consisted of spent lubrication
oil, used motor oil, castor oil, caprylic/capric triglyceride,
silicone oil 350, silicone oil 1000, basil oil 150, base oil 500,
and n-butyl stearate, respectively;
[0024] FIG. 16 is a photographic view of the surface and interior
of a mortar specimen incorporating a hydrophobic admixture of 30 wt
% crumb rubber particles, 10 wt % lubricant oil and SPAN 20 blend,
20 wt % activated carbon, and 40 wt % silica fume, wherein the
surfactant to lubricant oil weight ratio is 3:7;
[0025] FIG. 17 is a photographic view of the surface and interior
of a mortar specimen incorporating a hydrophobic admixture of 30 wt
% crumb rubber particles, 10 wt % lubricant oil and SPAN 20 blend,
20 wt % activated carbon, and 40 wt % spent RFCC catalyst, wherein
the surfactant to lubricant oil weight ratio is 3:7;
[0026] FIG. 18A is a photographic view of a cement paste specimen
incorporating a hydrophobic admixture of 30 wt % crumb rubber
particles, 10 wt % spent lubricant oil and SPAN 20 blend, and 60 wt
% activated carbon, wherein the surfactant to spent lubricant oil
weight ratio is 3:7 and FIGS. 18B and 18C are SEM images of the
specimen;
[0027] FIG. 19A is a photographic view of a cement paste specimen
incorporating a hydrophobic admixture of 30 wt % crumb rubber
particles, 10 wt % base oil 500 and SPAN 20 blend, and 60 wt %
activated carbon, wherein the surfactant to base oil weight ratio
is 3:7 and FIGS. 19B, 19C and 19D are SEM images of the
specimen;
[0028] FIG. 20A is a photographic view of a cement paste specimen
of a hydrophobic admixture of 30 wt % crumb rubber particles, 10 wt
% n-butyl stearate and SPAN 20 blend, and 60 wt % activated carbon,
wherein the surfactant to n-butyl stearate weight ratio is 3:7 and
FIGS. 20B and 20C are SEM images of the specimen; and
[0029] FIG. 21A is a photographic view of a cement paste specimen
incorporating a hydrophobic admixture of 30 wt % crumb rubber
particles, 10 wt % n-butyl stearate and SPAN 20 blend, 40 wt %
activated carbon, and 20 wt % silica fume, wherein the surfactant
to n-butyl stearate weight ratio is 3:7 and FIGS. 21B, 21C and 21D
are SEM images of the specimen.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] The present invention provides hydrophobic admixtures that
impart hydrophobic properties to cementitious materials without
adversely affecting the strengths of the cementitious materials.
The hydrophobic admixture includes solid polymer particles that
have a surface coating comprising a hydrophobic agent. Preferred
embodiments of the admixture also include a surfactant that is
blended into the hydrophobic agent and fine particles that are
distributed in the admixture.
[0031] The solid polymer particles are preferably crumb rubber
particles that are derived from used or waste tires, recycled
plastics, and other sources of polymeric waste materials. Where the
source is waste tires, the crumb rubber is recycled tires in a
process that initially separates the rubber component from the
steel wires, glass fibers, and other non-rubber materials;
subsequently, debris-free rubber is recovered by cryogenic freezing
with liquid nitrogen or other suitable means. The rubber then is
mechanically grounded and screened into irregular-shaped particles
of the desired size that typically ranges from 100-1000 .mu.m and
preferably from 300-600 .mu.m. The crumb rubber comprises natural
rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber,
and/or isoprene rubber. These polymers are typically cross-linked
by organic sulfur compounds that improve the durability and
strength of cured rubber. The solid polymer particles serve as
carrier particles for the hydrophobic agent and typically comprise
10 to 40% and preferably 15 to 30% by weight of the hydrophobic
admixture.
[0032] The fine particles refer to non-polymeric materials with
diameters that typically range from 1 to 1000 .mu.m and preferably
from 1 to 500 .mu.m. The non-polymeric materials can be reclaimed
from the waste materials. Preferred fine particles includes, for
example, activated carbon, silica fume which is reclaimed from
thermal cracking unit or incinerator bottoms, and spent catalyst
which is reclaimed from an FCC (fluid catalytic cracking) unit in a
refinery. The fine particles are particularly suited for filling
the large pores or cracks in the cement matrix to increase the
mechanical strength of the hydrophobic cementitious material. Some
fine particles have polar functional groups on their surfaces that
bond to the cement matrix. When fine particles are used, these
particles typically comprise 1 to 80% and preferably 40 to 60% by
weight of the hydrophobic admixture. The weight ratio of the solid
polymer particles to fine particles typically ranges from 2:1 to
1:2. In a preferred embodiment, the weight ratio of (i) the
combination of solid polymer particles and the fine particles to
(ii) the hydrophobic agent ranges from 10:1 to 10:3.
[0033] The hydrophobic agent refers to a material, which is liquid
at ambient temperatures (20.degree. C.), and that does not adsorb
or absorb water and which forms a coating on treated solid polymer
particles. Preferred hydrophobic agents are hydrocarbon hydrophobic
agents that include, for example, waste lubricant oil, spent motor
oil, base oil, ester of fatty acids, and vegetable oil. The
hydrophobic agent typically comprises 0.1 to 15% and preferably 1
to 10% by weight of the hydrophobic admixture.
[0034] The surfactant refers to any molecule having both a polar
hydrophilic head group, which energetically prefers solvation by
water, and a hydrophobic tail that is not well solvated by water.
The surfactant reduces surface tension when dissolved in water or
water solutions, or reduces interfacial tension between two
liquids, or between a liquid and a solid. A cationic surfactant has
a cationic head group, an anionic surfactant has an anionic, and an
amphoteric surfactant simultaneously carries both the anionic and
cationic head groups. The surfactant is preferably incorporated
into the hydrophobic agent to form a viscous modified hydrophobic
agent before being mixed with the solid polymer particles.
Preferred surfactants have an HLB value of 1.0 to 15.0 and
preferably 5.0 to 10.0. When a surfactant is used, the surfactant
typically comprises 1 to 20% and preferably 1 to 15% of the
hydrophobic admixture. The surfactant is preferably blended with
the hydrophobic agent and weight ratio of surfactant to hydrophobic
agent in the blend typically ranges from 0.1 to 0.7 and preferably
0.1 to 0.5.
[0035] To avoid the influence of ions on cement hydration,
non-ionic surfactants are preferred. SPAN and TWEEN series
surfactants are commercially available non-ionic surfactants which
have advantages over ionic surfactants, such as increased
stability, formulating flexibility and wider compatibility. TWEEN
surfactants are polyethoxylated sorbitan esters and SPAN
surfactants are sorbitan esters. They are stable in mild acids,
alkalis and electrolytes and over a wide pH range. In particular,
the non-ionic surfactants are preferably selected from TWEEN series
(20-21-40-60-61-65-80) and SPAN series (20-40-60-80-83-85-120)
which are further described in Table 1.
TABLE-US-00001 TABLE 1 Chemical Identities and Hydrophile Lipophile
Balance of SPAN and TWEEN Surfactants HLB HLB Product Identity
value Product Identity value SPAN 20 Sorbitan 8.6 TWEEN 20 PEG-20
16.7 monolaurate sorbitan monolaurate SPAN 40 Sorbitan 6.7 TWEEN 21
PEG-4 13.3 monopalmitate sorbitan monolaurate SPAN 60 Sorbitan 4.7
TWEEN 40 PEG-20 15.6 monostearate sorbitan monopalmitate SPAN 80
Sorbitan 4.3 TWEEN 60 PEG-20 14.9 monooleate sorbitan monostearate
SPAN 83 Sorbitan 3.7 TWEEN 61 PEG-4 9.6 sesquioleate sorbitan
monostearate SPAN 85 Sorbitan 1.8 TWEEN 65 PEG-20 10.5 sorbitan
tristearate SPAN 120 Sorbitan 4.7 TWEEN 80 PEG-20 15.0 isostearate
sorbitan monoolate
[0036] The SPAN products listed in Table 1 are partly soluble in
water at 10% w/w at 25.degree. C. TWEEN 20 and 60 are also partly
soluble, whereas TWEEN 40 and 60 are soluble and TWEEN 65 forms a
gel in water. Due to the lower HLB values, SPAN surfactants have
better solubilities in an oil phase than the TWEEN surfactants.
SPAN surfactants were selected for further testing and mixed with
the hydrophobic agent to coat the polymer particles.
[0037] Contact angle is the angle between a static drop of water
and a flat and horizontal surface upon which the droplet is placed.
The contact angle is conventionally measured through the liquid,
where a liquid/vapor interface meets a solid surface, and
quantifies the wettability of a solid surface by a liquid. The
higher the contact angle, the higher the hydrophobic interaction
between the surface and the liquid. If the liquid spreads
completely on the surface and forms a film, the contact angle is
zero degrees. As the contact angle increases, the wetting
resistance increases, up to a theoretical maximum of 180.degree.,
where the liquid forms spherical drops on the surface.
"Hydrophobic" is a term used to describe a wetting resistant
surface where the reference liquid is water. The higher the contact
angle, the higher the hydrophobic interaction between the surface
and the liquid. With the present invention, incorporation of the
hydrophobic admixture into a cementitious material renders the
cured or set cementitious material hydrophobic so that the its
surface can generate a contact angle of greater than 90.degree.
with water as the reference liquid. Preferred set cementitious
materials will have contact angles of at least 45 degrees and more
preferably greater than 90 degrees.
[0038] A method of preparing the hydrophobic admixture is to first
incorporate the hydrophobic agent such as waste lubricant oil with
a surfactant by mixing the components together to yield a modified
hydrophobic agent that has the consistency of a viscous liquid
wherein the surfactant is dispersed within the hydrophobic agent.
The modified hydrophobic agent is then mixed with the solid polymer
particles such as crumb rubber. If fine particles such as activated
carbon are used, they are blended into the mixture to form a
hydrophobic admixture that is ready for use.
[0039] The hydrophobic admixture of the present invention is mixed
with cementitious materials such as hydraulic cement binder and
water to form a cement mixture. Pozzolans, fine aggregates and
coarse aggregates can be added as necessary. The weight ratio of
the hydrophobic admixture to cementitious materials (including
cement and aggregates) is typically from 1:1 to 1:100 and
preferably from 1:1 to 1:10. As illustrated in FIGS. 1A and 1B, as
the cement mixture cures, hydrated cement (2) consisting of cement
particles and water forms throughout the cement solution or matrix
(4). Each hydrated cement (2) is surrounded by treated solid
polymer particles (14). Some isolated solid polymer particles 12
are distributed within the cement matrix (4). Fine particles are
not shown.
[0040] As shown in FIGS. 1C and 1D, the treated solid polymer
particle comprises a solid polymer particle (6) with a layer (8) of
modified hydrophobic agent that is coated on the exterior surface
of the particle (6). The alignment of the surfactants (10) within
the layer (8) further improves the exterior surface properties of
the solid polymer particle (6) so that the hydrophobic solid
particles, as the carrier along with the carried hydrophobic agent,
form a thin continuous oil phase around each hydrated cement (2).
Hydration of the cement paste proceeds without interference of the
modified hydrophobic agent in the continuous oil phase. Upon
completion of the hydration, the thin continuous oil phase provides
excellent hydrophobic property and mechanical strength for the
cementitious materials. When set or cured, the cementitious
material has a compressive strength of 15 to 50 MPa and preferably
of 25 to 40 MPa.
[0041] Cement Paste Samples
[0042] Cement pastes containing different hydrophobic admixtures
were initially evaluated for hydrophobic properties. Various
hydrophobic admixtures comprising different amounts of (i) crumb
rubber, (ii) waste lubricant oil (hydrophobic agent), (iii) SPAN 20
(HLB=8.6) and SPAN 80 (HLB=4.3) (non-ionic surfactant) and (iv)
activated carbon were incorporated into cement pastes to assessment
hydrophobic characteristics. The crumb rubber was made from rubber
tires and were 300 to 600 .mu.m in size. In particular, various
surfactant/hydrophobic agent blends (SHB) were prepared by mixing
the non-ionic surfactant and waste lubricant oil in the weight
ratios of 0:10, 1:9 and 3:7. Various crumb rubber and activated
carbon (RAC) combinations were tested wherein the crumb rubber
particles and activated carbon particles were in the weight ratios
of 10:0, 8:2, 6:4, 4:6, 2:8 and 0:10. Selected hydrophobic
admixtures had different weight proportions of SHB to RAC
combinations which ranged from ratios 10:0, 10:1, 10:2, . . . ,
10:9, and 0:10) to obtain the hydrophobic admixture. In practice,
each hydrophobic admixture was prepared by first thoroughly
blending the crumb rubber with the SHB and then subsequently adding
the activated carbon, if any.
[0043] In the preparing individual cement paste samples, cement
powder and the hydrophobic admixture were mixed in a weight ratio
of 10:1. The water to cement weight ratio was 0.45. The cement
paste samples were poured into petri dishes and allowed to cured
for 28 days at ambient temperature of about 20.degree. C. Water
droplets were deposited on the surface of the samples and the
contact angles were evaluated visually.
[0044] In general, it was observed that hydrophobic admixtures that
contained neither the surfactant nor activated carbon conferred
minimal hydrophobicity improvements to the cement paste samples.
That is, modified rubber particles with adsorbed waste lubricant
oil alone provided minor improvements in water repellency. However,
modified rubber particles with the surfactant/hydrophobic agent
blend (waste lubricant oil and non-ionic surfactant) did enhance
water repellency significantly. In addition, modified rubber
particles with the hydrophobic agent and activated carbon also
improved water repellency. Representative cured cement samples with
water droplets deposited thereon are shown in FIGS. 2 to 6. FIGS.
2A, 2B, and 2C are cured cement paste samples made from cement
powder, crumb rubber, lubricant oil, and activated carbon but with
no surfactant. Each sample was 6 cm in diameter. In particular, the
hydrophobic admixture included 30 wt % crumb rubber while the
combined amount of crumb rubber and activated carbon (if any)
comprised 85-90 wt % of the hydrophobic mixture. The weight ratio
of activated carbon to crumb rubber was varied. The weight ratio of
crumb rubber to activated carbon of the samples was 10:0 (FIG. 2A),
6:4 (FIG. 2B) and 4:6 (FIG. 2C) respectively. The images show a
modest increase in the contact angle with increasing activated
carbon levels. Thus, even without the surfactant, use of activated
carbon improved water repellency.
[0045] FIGS. 3A, 3B, and 3C are cured cement paste samples made
from cement powder, crumb rubber, lubricant oil, activated carbon,
and SPAN 20. In particular, the hydrophobic admixture included 30
wt % crumb rubber, 10 wt % spent lubricant oil and SPAN 20 blend,
wherein the weight ratio of surfactant to spent lubricant oil in
the blend was 3:7. The combined amount of crumb rubber and
activated carbon (if any) comprised 85-90 wt % of the hydrophobic
mixture. The weight ratio of activated carbon to crumb rubber was
varied. The weight ratio of crumb rubber to activated carbon of the
samples is 10:0 (FIG. 3A), 6:4 (FIG. 3B) and 4:6 (FIG. 3C),
respectively. The images show an increase in the contact angle with
increasing activated carbon levels.
[0046] FIGS. 4A, 4B, and 4C are cured cement paste samples made
from cement powder, crumb rubber, lubricant oil, activated carbon,
and SPAN 80. In particular, the hydrophobic admixture included 30
wt % crumb rubber, 10 wt % spent lubricant oil and SPAN 80 blend,
wherein the weight ratio of surfactant to spent lubricant oil in
the blend was 3:7. The combined amount of crumb rubber and
activated carbon (if any) comprised 85-90 wt % of the hydrophobic
mixture. The weight ratio of activated carbon to crumb rubber was
varied. The weight ratio of crumb rubber to activated carbon of the
samples is 10:0 (FIG. 4A), 6:4 (FIG. 4B) and 4:6 (FIG. 4C),
respectively. The images show an increase in the contact angle with
increasing activated carbon levels.
[0047] Increasing the percentage of non-ionic surfactants or
activated carbon in the hydrophobic admixture can improve the water
repellency of the cement paste samples. The cement pastes
containing SPAN 20 exhibited higher water repellency as compared to
those with SPAN 80, which has lower HLB value. The higher
lipophilic (oil-like) nature of SPAN 80 makes it less dispersible
in aqueous cement matrices.
[0048] Mortar Samples
[0049] Cement mortar specimens incorporating different hydrophobic
admixtures were tested and compared to control cement mortar
specimens made (i) with untreated crumb rubber as the admixture and
(ii) without any admixture. The mixing weight ratio for the control
mortar specimens without any admixture was: 1 cement:2.75 sand:0.6
water. For example, if the starting amount of hydraulic cement is
100 grams, then 275 grams of silica sand and 60 grams of water are
needed.
[0050] For the test cement mortar specimens, 4.5 or 6 wt % of the
silica sand was replaced by a hydrophobic admixture. In the case of
4.5 wt % replacement, for 100 grams of hydraulic cement, 262.625,
12.375, and 60 grams of silica sand, hydrophobic admixture and
water, respectively, were used. The mortar specimens consisted of 5
cm square blocks.
[0051] The hydrophobic admixtures contained (i) crumb rubber, (ii)
waste lubricant oil (hydrophobic agent), (iii) SPAN 20 (non-ionic
surfactant), (iv) activated carbon, and, optionally (v) silica
fume. The surfactant hydrophobic blend was prepared by mixing SPAN
20 and waste lubricant oil in a weight ratio of 3:7. The blend was
mixed with the crumb rubber particles, fine powders to obtain the
hydrophobic admixtures.
[0052] The mortar specimens were prepared by dry mixing the cement,
sand and hydrophobic blend (if any) for 2 minutes and wet mixing
with the water for 6 minutes and casting the mix into cubic molds
(50.times.50.times.50 mm). After 24 hours, all the specimens were
cured in saturated limewater at room temperature.
[0053] Specimens containing only untreated rubber particles, cement
and sand were also prepared as controls.
[0054] Portland Type I cement used was produced by Taiwan Cement
Corporation. (Taiwan) Its physical-chemical properties are set
forth in Table 2. Refined sand used was from Ching-Ching Foundry
Sand Co., Ltd. (Taiwan) The chemical composition and grain
distribution of the sand are given in Table 3. Measurements of
compressive strength were conducted according to ASTM C109.
TABLE-US-00002 TABLE 2 Composition of Portland Type I Cement (Wt %)
Composition Content SiO.sub.2 20.42 Al.sub.2O.sub.3 4.95
Fe.sub.2O.sub.3 3.09 CaO 61.96 SO.sub.3 2.40 MgO 3.29 Loss on
ignition 1.75 Insoluble residue 0.5 C.sub.3S 49 C.sub.2S 21
C.sub.3A 7.9 C.sub.4AF 9.4
TABLE-US-00003 TABLE 3 Chemical composition and grain distribution
of sand Chemical composition (wt %) Sieve size (.mu.m) SiO.sub.2
Al.sub.2O.sub.3 Fe.sub.2O.sub.3 841 595 420 297 210 149 97.5% 2.06%
0.07% 2.2% 29.3% 55.6% 12.3% 0.5% 0.1%
Example 1
[0055] In this example, control mortar specimens were prepared
without any additives. Their compressive strengths were measured
after 7, 14 and 28 day of being cured. Test mortar specimens were
prepared where the hydrophobic admixture replacement levels for
silica sand were 4.5 and 6 wt % and their compressive strengths
were also measured. Table 4 sets forth the components of the
different hydrophobic admixtures used. The hydrophobic oil used was
spent lubricant oil. The amount of oil listed is a blend includes
both the lubricant oil and SPAN 20 surfactant. The SPAN 20 to
lubricant oil ratio of the blend is in a weight ratio of 3:7.
TABLE-US-00004 TABLE 4 (1) Control mortar without additive
Compressive Strength (MPa) 7 days 14 days 28 days 26.786 35.829
39.019 Composition of Admixture (wt %) Compressive Strength (MPa) R
O AC 7 days 14 days 28 days (2) Admixture replacement levels for
silica sand were 4.5 wt % 100 0 0 11.806 13.551 15.412 90.91 9.09 0
12.305 15.583 16.992 66.67 16.67 16.67 13.167 14.92 17.191 46.15
23.08 30.77 13.151 14.993 17.934 28.57 28.57 42.86 17.042 19.998
22.234 (3) Admixture replacement levels for silica sand were 6 wt %
100 0 0 13.174 14.431 17.016 90.91 9.09 0 14.673 17.006 19.336
66.67 16.67 16.67 15.605 18.387 21.46 46.15 23.08 30.77 16.677
18.149 21.007 28.57 28.57 42.86 16.706 19.841 23.474 Note: R--Crumb
rubber particles O--Spent lubricant oil AC--Activated carbon
[0056] The mortar specimen containing untreated crumb rubber as the
sole additive had lower compressive strengths than the control
specimen. The presence of the hydrophobic admixture reduced the
compressive strengths of the mortars relative to that of the
control mortar without any additive. High levels of rubber and oil
decreased the compressive strengths of the mortar specimens. The
presence of activated carbon increased the compressive
strengths.
Example 2
[0057] In this example, test mortar specimens were prepared where
the hydrophobic admixture replacement levels for silica sand was
4.5 wt % and their compressive strengths measured. Table 5 sets
forth the components of the different hydrophobic admixtures used.
The hydrophobic oil used was spent lubricant oil. The amount of oil
listed is a blend that includes both the lubricant oil and SPAN 20
surfactant. The SPAN 20 to lubricant oil ratio of the blend is in a
weight ratio of 3:7.
TABLE-US-00005 TABLE 5 (1) Control mortar without additive
Compressive Strength (MPa) 7 days 14 days 28 days 26.786 35.829
39.019 (2) MRP replacement levels for silica sand were 4.5 wt %
Composition of Admixture (wt %) Compressive Strength (MPa) R O AC 7
days 14 days 28 days 100 0 0.sup. 11.806 13.551 15.412 80 0 20
.sup. 26.057 28.014 33.903 60 0 40 .sup. 27.301 33.531 36.917 50 0
50 .sup. 29.948 37.523 42.245 40 0 60*.sup.5 29.953 35.566 43.66
72.7 7.3 20 .sup. 13.027 16.16 18.181 52.2 7.8 40*.sup.7 22.425
27.931 31.066 41.7 8.3 50*.sup.8 27.233 32.457 34.022 35 5
60*.sup.6 30.754 38.384 42.068 32 8 60*.sup.9 31.001 36.921 42.321
30 10 .sup. 60*.sup.10 29.192 34.771 39.081 66.7 13.3 20 .sup.
11.208 14.031 15.237 46.2 13.8 40 .sup. 16.622 19.49 22.183 35.7
14.3 50 .sup. 21.152 26.16 29.673 25.0 15.0 .sup. 60*.sup.11 26.929
31.352 33.096 15.0 15.0 .sup. 70*.sup.12 28.975 35.221 39.504 5.0
15.0 .sup. 80*.sup.13 31.066 37.18 43.419 Note: R--Crumb rubber
particles O--Spent lubricant oil AC--Activated carbon *designates
mortar specimens subject to hydrophobicity assessment in Example 3.
The number associated with each (*) refers to the figure number in
the drawings.
[0058] The data demonstrate that the mortar specimen containing the
untreated crumb rubber had a lower compressive strength than the
control specimen. The results further show that incorporating
hydrophobic admixtures that contained a large percentage of oil can
significantly weaken the compressive strengths of the mortar
specimens. However, employing hydrophobic admixtures that have
above 50% activated carbon improved the compressive strengths of
the mortar specimens.
Example 3
[0059] The behavior of water droplets deposited on the surface of
the mortar specimen is an indicator of the effectiveness of the
hydrophobic admixtures. Water droplets were placed on the surfaces
of some of the mortar specimens that exhibited good compressive
strengths as described in Example 2. In particular, water droplets
were applied to the mortar specimens designated by (*) in Table 5
and photographs of the specimens taken about 30 seconds after the
water droplets were deposited.
[0060] FIGS. 5A and 5B are views of the mortar specimen wherein the
hydrophobic admixture comprised 40 wt % crumb rubber particles, no
lubricant oil, and 60 wt % activated carbon and no SPAN 20
surfactant. The water completely wets the surface and suggests that
this admixture combination conferred no water repellency. As shown
in FIG. 6, the mortar specimen with 35 wt % crumb rubber, 5 wt %
oil, and 60 wt % activated carbon exhibited no significant
improvement in the water repellency. However, improved water
repellency is evident in mortar specimens where the hydrophobic
admixture had more than 7 wt % oil as shown in the photographs of
FIGS. 7 through 13.
Example 4
[0061] In this example, hydrophobic admixture containing various
oil (hydrophobic agent) sources including spent lubricant oil, used
motor oil, castor oil, caprylic/capric triglyceride, silicone oil
350, silicone oil 1000, base oil 150N, base oil 500N, and n-butyl
stearate were tested. Test mortar specimens were prepared where the
hydrophobic admixture replacement levels for silica sand were 4.5
wt %. The amount of oil listed is a blend that includes both the
lubricant oil and SPAN 20 surfactant. The SPAN 20 to lubricant oil
ratio of the blend is in a weight ratio of 3:7. Table 6 summarizes
the effect of different oils on the compressive strengths of mortar
specimens.
TABLE-US-00006 TABLE 6 (1) Control mortar without additive
Compressive Strength (MPa) 7 days 14 days 28 days 26.786 35.829
39.019 Composition of Admixture (wt %) Compressive Strength (MPa)
Oil source R O AC 7 days 14 days 28 days (2) Mortar with Admixture
containing 5 wt % various oils Spent lubricant oil 35 5 60 30.754
33.384 42.068 Used motor oil 35 5 60 31.188 37.8 43.339 Castor oil
35 5 60 25.976 31.145 37.58 Caprylic/capric 35 5 60 23.798 28.15
33.605 triglyceride (3) Mortar with Admixture containing 10 wt %
various oils Spent lubricant oil 30 10 60 29.192 34.771 39.081 Used
motor oil 30 10 60 30.887 36.568 41.972 Castor oil 30 10 60 22.819
26.901 31.274 Caprylic/capric 30 10 60 16.719 17.208 21.367
triglyceride Silicone oil 350 30 10 60 19.298 21.42 24.331 Silicone
oil 1000 30 10 60 18.501 22.694 25.598 Base oil 150N 30 10 60
28.254 36.116 44.424 Base oil 500N 30 10 60 29.491 36.181 41.673
n-butyl stearate 30 10 60 27.336 28.549 39.593 Note: R--Crumb
rubber particles O--Oil AC--Activated carbon
[0062] The data demonstrate that the mortar specimens containing
castor oil, triglyceride, or silicone oil had lower compressive
strengths than the control mortar specimen with no additive. Mortar
specimens where the hydrophobic admixture contained petroleum-based
oils, including spent lubricant oil, used motor oil, base oil 150N,
or base oil 500N, had significantly higher compressive strengths
than those with untreated crumb rubber particles as the sole
additive or those with no additives.
[0063] Water droplets were placed on the surfaces of mortar
specimens and photographs of the specimens taken about 30 seconds
after the water droplets were deposited. The series of images in
FIGS. 14A to 14D show the surface and interiors of the mortar
specimens with 35 wt % rubber, 60 wt % activated carbon, and 5 wt %
oil consisting of spent lubricant oil, used motor oil, castor oil,
and caprylic/capric triglyceride, respectively.
[0064] The series of images in FIGS. 15A to 15I show the surface
and interiors of the mortar specimens with 30 wt % rubber, 60 wt %
activated carbon, and 10 wt % oil consisting of spent lubricant
oil, used motor oil, castor oil, caprylic/capric triglyceride,
silicone oil 350, silicone oil 1000, base oil 150, base oil 500,
and n-butyl stearate, respectively.
[0065] It is evident that hydrophobic admixtures containing 10 wt %
oil improved the water-repelling properties of both surface and
inside of mortar specimens than that of 5 wt % oil. The contact
angle for the inner surface was large which confirmed that the
hydrophobicity in the interior of the sample was good. It also
demonstrates that the hydrophobic admixture was uniformly dispersed
in the cement paste and not just on the surface.
Example 5
[0066] In this example, hydrophobic admixtures were formed by
mixing crumb rubber particles, spent lubricant oil, activated
carbon, and silica fume or spent RFCC catalyst. Test mortar
specimens were prepared where the hydrophobic admixture replacement
levels for silica sand were 4.5 wt %. The amount of oil listed is a
blend that includes both the lubricant oil and SPAN 20 surfactant.
The SPAN 20 to lubricant oil ratio of the blend is in a weight
ratio of 3:7. Table 7 summarizes the compressive test results.
TABLE-US-00007 TABLE 7 Composition of Admixture (wt %) Compressive
Strength (MPa) R O AC SF 7 days 14 days 28 days 30 10 60 0 29.192
34.771 39.081 30 10 40 20 21.978 23.593 29.612 30 10 20 40 22.445
27.082 32.041 Composition of Admixture (wt %) Compressive Strength
(MPa) R O AC RFCC 7 days 14 days 28 days 30 10 60 0 29.192 34.771
39.081 30 10 40 20 23.962 31.581 35.743 30 10 20 40 15.769 19.505
21.231 Note: R--Crumb rubber particles O--Spent lubricant oil
AC--Activated carbon SF--Silica fume RFCC--Spent residual oil fluid
catalytic cracking catalyst
[0067] The addition of silica fume or RFCC reduced the compressive
strengths of the mortar specimens. FIGS. 16 and 17 are photographs
of the surface and interior of the specimens made with hydrophobic
admixtures containing 30 wt % rubber particles, 10 wt % oil, 40 wt
% activated carbon, and 20 wt % silica fume or RFCC, respectively.
The water repellencies of these mortar specimens appear to be
comparable to that of the mortar specimen made of the hydrophobic
admixture with 30 wt % rubber particles, 10 wt % oil, and 60 wt %
activated carbon, as shown in FIG. 10.
Example 6
[0068] The microstructures of the hydrated cement pastes made with
selected hydrophobic admixtures were examined with a scanning
electron microscope. The cement powder and admixtures were mixed in
a weight ratio of 10:1. The water to cement weight ratio was 0.45.
The cement paste samples were poured into petri dishes and allowed
to cured for 28 days at ambient temperature of about 20.degree. C.
Water droplets were deposited onto the cured cement paste samples.
Table 8 sets forth the admixture components of 4 samples tested.
The oil component includes SPAN 20 surfactant, wherein the
surfactant to oil weight ratio is 3:7
TABLE-US-00008 TABLE 8 Composition of Admixture (wt %) R O AC SF 30
10 (SL) 60 0 30 10 (BO) 60 0 30 10 (BS) 60 0 30 10 (BS) 40 20 Note:
R--Crumb rubber particles O--(SL) is spent lubricant oil; (BO) is
base oil 500; (BS) is n-butyl stearate AC--Activated carbon
SF--Silica fume
[0069] FIG. 18A is a photograph of the first specimen and FIGS. 18B
and 18C are SEM images of the specimen.
[0070] FIG. 19A is a photograph of the second specimen and FIGS.
19B, 19C and 19D are SEM images of the specimen.
[0071] FIG. 20A is a photograph of the third specimen and FIGS. 20B
and 20C are SEM images of the specimen.
[0072] FIG. 21A is a photograph of the fourth specimen and FIGS.
21B, 21C and 21D are SEM images of the specimen.
[0073] The photographs show that each of the cement paste specimens
exhibited good hydrophobic properties. The SEM images show a very
tight and uniform microstructure and that the hydrophobic carrier
and agent are well dispersed in the cement matrix. The SEM images
show that more amorphous calcium-silicate-hydrate (C--S--H) gel is
formed, which indicates that the addition of hydrophobic admixture
of into cement paste did not adversely affect the cement hydration.
The formation of different morphologies of C--S--H gel is due to
the different phase compositions of the gel.
* * * * *