Note: Descriptions are shown in the official language in which they were submitted.
12~ 86
This invention re].atefl to an improved concrete, ~nd in particulflr to
what can be characterized by a polymer concrete ill which a monomer polymerized
in situ is used as the binder component for the concrete aggregate instead of
conventional hydraulic binders which require the addition of water to set.
More specifically, the present invention relates to a polymer con-
crete free oE water in which the polymeric binder comprisefl furfuryl alcohol
monomer polymerized in situ with the aid of an acid catalyst.
Generally, a significant proportion of concrete used today in pave-
ments, structural supports for buildings and machinery and other widely known
uses is formed from a mixture of fine and coarse mineral aggregates and a paste
of Portland cement and water. Such Portland cement formulations comprise from
about 60% to 75% aggregates and from about 25% to 40% paste by volume of the
formulation. The quality of Portland cement concrete depends on many factors
including the type of aggregate used and gradation of the aggregate size as
well as the quality and availability of the paste and the amount and quality
of the water relative to the amount of Portland cement added.
; Studies and tests have been performed on polymeric additives to con~
crete and polymeric materials used as substitutes for the typical hydraulic
cement binder materials. For example, polymer cement concrete which is a
mixture of convantional hydraulic cement concrete and high molecular weight
polymers has been formed comprising generally thermoplaGtic or rubber polymers
which are added as emulsions or dispersions to the hydraulic concrete mix.
Polymers which have been utilized in such systems include polyvinylacetate,
polyacrylates, polyvinylchloride, styrene-butadiene and polyvinylidenechloride.
Copolymers of two or more of the polymers have also been utilized. While
improvements in the physical properties such as compressive strength, bending
strength and decreased water peremeability have been reported in the literature
for these polymer cement concretes, these improvements have been offset by
significant dimensional shrinkage. It has been found that the wear-resistance
of polymer cement concretes is significantly better than Portland cement
--1--
concrete ancl thus, polymer cement concretes have eound some ufle A8 ~loor and
deck COVerirlgR in public buildingA, indu~trial plants and brLdges.
Over the last ~ifteen years, extensive laboratory studies have been
performed in the United States on both polymer-impregnated concrete and polymer
concrete in which the hydraulic binder i8 totally substituted with a polymeric
material. Such studiefl have primarily focused on solvLng problem~ on failing
concrete bridge decks and on concrete pipe in corrosive waste water environ-
ments. Polymer-impregnated concrete consists of polymer-impregnation of
Portland cement concrete with a low viscosity monomer that is subsequently
polymerized in situ. The monomer penetrates the concrete matrix to a finite
depth (sometimes controlled) and i8 subsequently polymerized by heat, catalysts,
or radiation. Significant property improvements in compressive strength (285%),
tensile strength (292%), modulus of elasticity (80%), freeze-thaw durability
(300%) and water permeability have been reported by U.S. Department of Interior/
Bureau of Reclamation, W. C. Cowan & H. C. Riffle Investigation of Polymer-
Impregnated Concrete Pi~, September, 197~. Data on the resistance of polymer-
impregnated concrete to mild hydrochloric and sulfuric acids and permeation by
chloride was presented by the Brookhaven National Laboratory in 1976, L. E.
KuKacka and M. Steinberg Concrete-Polymer Composites,_A Material For Use In
Corrosive Environments, March, 1976.
Polymer concrete differs from typical Portland cement concrete,
polymer cement concrete and polymer-impregnated concrete. Polymer concrete
contains no cement or water. The development of physical and chemical proper-
ties of polymer concrete depends entirely on the chemical and slightly physical
reaction between the polymeric binder, hardener and the aggregate system. Most
of the early experimentation on polymer concrete has occurred in Eastern Europe
and the Soviet Union. More recent experimentation in the United States has
focused on bridge deck and highway repairs and experimental attempted use of
a polymer concrete lining for steel pipe in geothermal applications. Few
commercial applications of polymer concrete are known, but experimental use of
--2--
36
polymer concrete materials has been ongoing since about l960. ai'or exaMple, in
bridge deck and geothermal applications, polymer concrete syRtems containing
methylmethacrylate and blends of polyester/styrene have been evaluated and
their properties have been measured and reported by G. W. DePuy, L. E. Kukacka,
Concrete-Po_ymer Materials, Fifth Topical Report, Brookhaven National Labora-
tory, December, 1973. Significant improvements in co~npressive strength
(18-20,000 PSI) water absorption (less than 1%) and chemical resistance are
obtained versus conventional Portland cement concretes. However, for appli-
cations in heavy industrial environments, even more chemically resistant
polymer concretes are needed.
The present invention provides a polymer concrete with improved
physical properties over conventional Portland cement concretes and which
can be used for a wide variety of uses such as coatings, coverings, repairs
and for applications in he~vy industrial environments in which strength,
flexibility and chemical resistance are required. It has been found that
furan resins, particularly those formed from furfuryl alcohol monomers can
be mixed with a novel aggregate system to yield polymer concretes of
improved chemical and physical characteristicfi. Furan polymers have found
wide ufie in the formation of foundry cores in which small-sized aggregates
(sand) are mixed therewith, all large-sized aggregates being excluded
from such formulations. Likewise9 there have been studiefi performed on
polymer concrete syste~s including polymer concrete systems utilizing furan
polymers in the United States, such as by the U.S. Atomic Energy Commission,
Oak Ridge National Laboratory, Oak Ridge, Tennessee, Translation Series AEC-
tr-7]47, ~ovember9 1971, and further testing on furan polymer concretes in
the Soviet Union in which it was found that the performance of polymer con-
cretes are significantly influenced by aggregate selection to produce furan
polymer concretes with a range of compressive strengths varying from 5000 to
15,000 PSI; I. M. Elshin, Scientific Research Institute of Hydrotechnics,
~iev, U.S.S.R., "Experience in Using Plastic Concrete with Furan Resins in
-3-
lz~.s~7a6
Di~ferent Structures". Likewise, Sneck, Tenho, Martt;ne.r, Pertti, ~neback,
and Carl, The State Institute for Technical Research, Otamiemi, FLnland,
A Preliminary Investigation on the Properties of Some Fufural Acetone Resin
Mortars, have tested various physical properties of furan polymer concretes
as has The Quaker Oats Company, Chemical Division, Chicago, Illinois.
In accordance with the present invention, an improved polymer con-
crete is provided in which a resin binder of polymerized furfuryl alcohol is
formed in situ within a novel aggregate system.
Briefly, the polymer concrete of the present invention comprises
about 40 to about 70% by weight coarse aggregate, about 20 to about 55% by
weight fine aggregate (sand), about 2 to about 15% silica flour and about 8
to about 12% furan resin formed by the in situ polymerization of furfuryl
alcohol with aid of an acid catalyst. It has been found that by varying the
aggregate formulation within the disclosed range, furan polymer concretes can
be produced with compressive strengths varying from 5000 to 15,000 PSI, r
flexural strengths of 2500 to 5400 PSI and tensile strengths of about 2000
PSI. Porosity can be controlled by varying the aggregate gradation, binder
level and curing temperature.
Ln accordance with the teachings of the present invention, certain
factors have been recognized which are critical if a viable furfuryl alcohol
polymer concrete is to be produced. Accordingly, it has been found that aggre-
gate sources and types of aggregates are critical to achieve proper curing and
high strength. In particular, aggregate size gradations as well as the pH of
the aggregate components must fall within the range set forth in the present
invention. Moisture content is very critical and must be minimized. Relatively
high moisture content retards cure and greatly reduces strength of the furan
polymer concrete. Control of the polymerization reaction is important
especially when large batches of the concrete product are made to allow for
uniform mixing and ease of pouring.
The furan polymer concretes of the present invention when cured
--4--
~21~37~6
produce a highly cross-linked resinous concrete in which the aggregate
materials are dispersed within the resin binder. The furan polymer concretes
of the present invention offer the broadest range of chemical resistance over
all other types of polymer concretes which are based upon different polymer
systems or based on furan polymer system~ of different aggregate type~.
Accordingly, it is an object of the present invention to provide an
improved concrete.
In accordance with the aforementioned object, another object of the
present invention i9 to provide a polymer concrete in which a furan polymer
is utilized as the binder for the concrete aggregate system, replacing typical
hydraulic cement and water binder systems.
Another object of the present invention ;s to provide a polymer
concrete devoid of water and which is formed from the in situ polymerization
of furfuryl alcohol monomer mixed with an aggregate system to provide a con-
crete product which can be used successfully for a wide variety of purposes.
Still another object of the present invention is to provide an
improved furan polymer concrete which comprises the in fiitU polymerization
product of furfuryl alcohol monomer mixed with an aggregate syfitem comprising
coarse and fine aggregates of controlled size gradation to yield a concrete
product usable for a wide variety of purposes.
These together with other objects and advantages which will become
subsequent apparent reside in the details of the composition and method of
making same as more fully herein after described and claimed.
Specifically, the po]ymer concrete of the present invention is
formed from a blend of furfuryl alcohol mOnOMer and an acidic hardener
mixed with a mineral aggregate system. The furfuryl alcohol monomer is
polymerized in situ within the mixture to produce a highly cross-linked
resinous polymer concrete in which the mineral aggregates are dispersed
or bound within the polymer binder.
Polymer concretes formed from furan polymers offer the broadest
range Oe chemical resistance reported ancl are Eurther advanta~olls eor pro-
ducing fl usflble concrete prodllct becfluse Oe the relatively low viscosity,
ease of handling, mixing, consolidation, Elow aDd finish, rapid cure at
ambient temperatures of such concretes and because of the Pdvantageous
raw material availability and cost perEormance relative to other organic
binders which have been utilized in polymer concretes. The chemical
resistance of various polymer concretes are presented in TABLE 1.
TABLE l*
,, ,, , _ , . . , _ _ . . _ _ . . _ .
RELATIVE CHEMICAL RESISTANCE OF POLYMER CONCRETE AND PORTLAND
CEMENT CONCRRTE
, ~
Rated 1 (Poorest) to 10 (Best)
To Fats and
To To To To To Petroleum
Material Acids Oxidizers Alkali Salts Solvents Products
_r~ :: -_.. __ _ ____~_ - . _ ~, - _ _ _: _ . . ~ _ ~__~__._
Phenol PC 9-10 3-4 3-4 10 7 8
Furan PC 10 2-3 10 10 8 8
Polyester PC 8- 9 7 3-h 3-5 1-5 7-9
Epoxy PC 9 3 8 5-6 3-7 9
Portland Cement 1 1 9 2-3 3-7 5-6
Concrete
.
*Taken from Translation Series AEC-tr-7147, November, 1971, U.S. Atomic
Energy Commission, Oak Ridge National Laboratory, Oak Ridge, Tennessee.
Furfuryl alcohol monomer cures in the presence of most inorganic,
organic and latent acid hardeners, such as phosphoric acid, sulfuric acid,
urea nitrate, benzene sulfonic acid, and toluene sulfonic acid. Selection of
an optimum catalyst system, whether solid or liquid, depends on many factors
including the field conditions in which the polymer concrete is to be used.
Such field conditions as temperature, humidity and batch size of the polymer
concrete must be considered since all of these condition will be a factor in
which catalyst system is utilized.
~:9.l3~786
Furtller, the perEormance of Euran polymer concrete i8 significantly
influenced by aggregate selection including type and size gradation. Many
fine and coarse aggregate types are available and can be chosen to produce
furan polymer concretes with a range of compres6ive strengths varying from
5000 to 15,000 PSI. It has been found that the size gradation of both the
coarse and fine aggregates used in polymer concrete mixture not only affect
the compressive strengths of the polymer concrete but greatly influence the
ability to form a uniform concrete mixture, ease of handling and chemical
resistance properties of the formed polymer concrete. Furthermore, aggregates
containing base substances such as carbonates, limestone, sandstone and clay
are undesirable because these impurities neutralize the hardener (acid cata-
lyst) and as such optimum property development will not occur. Accordingly,
the aggregate must have a pH less than 7 in order to produce a concrete
product which can be used successfully in the field.
The polymerization rate and the final properties of furan polymer
concrete are also greatly influenced by the amount of moisture in the aggregate.
Published data has shown that when containing as little as 5% to 6~ moisture
in the aggregate, the furan polymer concrete develops very low compressive
strength, and at higher moisture contents, the material will not harden.
Accordingly, to produce a high quality furan polymer concrete, the aggregate
which is selected must have the proper sizing, be clean and free of any
alkaline impurities, and have a moisture content preferably below 1%.
Initial laboratory work on furan polymer concretes focused on char-
acterizing and optimizing the chemical property development, binder levels,
handling properties and chemical resistance. In performing this work, three
aggregates and a 65~ toluene sulfonic acid hardener in water were used.
Various binder and hardener levels and curing temperatures were evaluated. To
produce laboratory test specimens, the components were mixed according to the
following procedures:
The dried aggregates were blended for 3 minutes, using a small motor
~LZ1878~i
mixer, while the hardener was slowly added to the aggregflte. In flome casefl it
was necessary to further dilute the hardener with solvent to insure uni~orm
distribution. Careful attention was given to measuring the hardener, since
concentration influenced polymerization rate and mechanical propert;es. Excess
hardener led to nearly installtaneous setting of the mix and poor physical prop-
erties. The binder was added to the hardener/aggregate blend and mixed for
5 minutes. The mixed furan polymer concrete was placed in l-inch diameter by
2-inch high compression molds and allowed to cure at room temperature for
~ourteen dayæ. Data on resulting mechanical properties versus type-l Portland
cement concrete are shown in TABLE 2.
TABLE 2
MECHANICAL PROPERTIES OF F~EA~ PC MlXES CURED 14 DAYS
VS .
TYPE l PORTLAND CEMENT CONCRETE CURED 28 DAYS
Type 1 Portland
Furan PC Mix (Wt. %) Cement Concrete
.... . .. . ...
Component Mix A Mix B Mix C 5.5 Bag Mix 7 Bag Mix
#8 Quartz 43.5 44.2 49.2
#50 Quartz17.4 17.7 22.5
Silica Flour 26.1 26.6 18,3
FA Binder 11.8 10.5 9.1
65% TSA Hardener 1.2 1.0 0.9
Total _ 100.00100.00 100.00
Compressive
Strength (psi)
ASTM C5796,370 6,660 5,030
ASTM C39 3.000 4 500
Flexural Strength
(psi )
ASTM C~80 2,880 2,680 3,310
ASTM C78 _ _ 500 750
Tensile Strength
(psi )
ASTM C307 1,470 1,550 1,250
_ _ , . . .
Porosity (Vol.%) 0.35 0.17 0.09
~21~7~3~
The same mixing procedures were Eollowed to obtai~ Hpecimen~ ~or
elevated temperature curing. Aeter curing Eor 14 days at room temperature,
the specimens were post cured for 1 houræ at 200 F. and an additional 2 hours
at 250 F. The affect of post cure on physical property development is shown
in TABLE 3. As can be seen from the TABLE, higher strengths and greater
porosity resulted Erom post curing. For most applications, minimum porosity
is desirflble.
_ TABLE 3 _
MEC~ANICAL PROPERTIES OF FURAN PC
POST CURED AT ELEVATED TEMPERATURES
Test Mix A Mix B Mix C
Compressive Strength (PSI)10,74011,390 12,750
(ASTM C579)
Flexural Strength (PSI) 2,550 5,400 5.400
(ASTM C580)
Tensile Strength (PSI) 1,980 2,070 2,000
(ASTM C307)
Porosity (Vol. %)1.12 .42 .38
Published information has further characterized the mechanical prop-
erties of furan polymer concretes. Such published studies have illustrated
the compressive strength development of furan polymer concrete as a function
of time at 20 C. and 73 relative humidity using a 14% binder/hardener level.
It has been found that at those defined conditions, approximately 28 days are
needed to develop maximum compressive strength properties. However, approxi-
mately 79% of ultimate strength is developed within 7 days and 95% within 14
days. Another published study has characterized the compressive strength
development of furan polymer concrete as a function of relative humidities.
The specimens contained in an 11% binder level and strengths were determined
after exposure to different relative humidities for 28 days at 20 C. This
study found that a significant sacrifice in compressive strength results when
~21~R6
the satnplefl are mixed and cured flt high relative humidities. Another study
has fihown the change o~ length (shrinkage) of furan polymer concrete with
time. In the published studies, various specimens were measured at 20U C.
and 73% relative humidity. The shrinkage measurements started after 24
hours cure and continued through 28 dayfl. The data reveal a low level oE
shrinkage (less than 0.72%) occurs, most during the first 7 days Oe ambient
cure.
Laboratory chemical resistance tests were conductéd by totally
immersing the poæt cured compression cylinders formed by the procedures set
forth above in selected reagents at 150 F. for various times. Changes in
compressive strength, weight, and color were observed. The 6-month data are
presented in TABLE 4. With the exception of immersion in 5% sodium hydroxide,
which attack the aggregate, furan polymer concrete exhibited excellent resis-
tance to the reagents. The reagent color changes may indicate only surface
attack of furan polymer concrete specimens.
TABLE 4
70 Compres~siveReagent Color
Strength 7 Weightat Six
_ Reagent _ ~etention _ _ _Change Months
Deionized Water 92 ~ .70 Clear
Saturated Sodium Chloride 105 ~ .16 Clear
5% Sodium Hydroxide49 - 5.46 ~lack
15% Hydrochloric Acid 100 ~ .13 Orange
Methyl Ethyl Ketone98 + .17 Black
Perchloroethylene 100 - .64 Green
Chlorobenzene 108 - .54 Yellow
--10--
~Z~ 7~3~
Further scale-up trials have been conducted to focus on aggregate
optimization, large scale handling properties and improved physical proper-
ties. Crushed granite stone conforming to ASTM D-448 seive æpeciEications
and silica sand conforming to ASTM C-33 were blended in various size ratios.
Moisture contents of the blends varied and were not part of the tests. Basic
concrete mix design and concrete test procedurefi were utiliæed. Compressive
strength tests were used as the strength criteria. Concrete test cylinder
molds 6 inches in diameter x 12 inches high were filled from a 30-pound batch,
prepared with a small mortar mixture. The mix procedure used for the labor-
atory tests was duplicated for these scaled trials. Various blends combiningaggregates with different particle sized distributions, different binder levels
and hardener levels were investigated. The mixing was performed at 50-60 F.
and relative humidities varying from 40-70%. As the ingredients were placed
in the concrete test cylinder molds, they were rodded and lightly screeded to
remove excess mix. No external vibration was used for consolidation. Tests
with the addition of glass reinforcement to the batch proved difficult to mix,
pour and finish, and did not improve physical property development.
TABLE 5 summarizes some typical findings of the scale-up tests.
With the exception of mix #1, the binder content of the mix is shown as con-
stant, so that the effect of aggregate size distribution on strength develop-
ment, handling and finished characteristics may be compared.
786
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~21~3~786
From ~ield tests in which the ~uran poLymer concrete was installed
as a pump base in a chemical plant, the following tactors were found:
(1) Aggregate sources and types are critical to achieve proper cure
and high strengths in furan polymer concretes.
(2) Mo;sture content is critical to set time and strength of furan
polymer concretes. Aggregates must be pre-dried in order to achieve consistent
results.
(3) Safety is a critical concern. The hardener needs to be pre-
blended with the aggregate in order to safely control the reaction time with
the furfuryl alcohol monomer binder.
(4) To achieve a suitable working time and good finishing, the
proportion of liquids in the batch must be in the proper range. To effect
economy this may mean adding some non-reactive dilutants to the batch.
(5) Control of the exothermic reaction is critical to minimize
shrinkage and permit good consolidation and finishing.
(6) To scale-up for pouring major structures with furan polymer
concrete, a system of automated field batching equipment appears to be
necessary. Control of environmental factors such as rain, humidity and
temperature would be certainly critical.
(7) Good adhesion of furan polymer concrete to Portland cement
concrete and to steel reinforcing can be achieved with the proper priming
system.
In accordance with the present invention, a furan polymer concrete
containing the following ingredients and proportions thereof has been found
to produce satisfactory results and can be used successfully in the numerous
known concrete applications:
Coarse aggregate40-70% by weight
Fine aggregate (sand)20-55% " "
Silica flour 2-15% " "
30 Furfuryl alcohol resin 8-12% " "
~2~1a7~6
An amino silane coupling agent may be added in minor amounts.
Further, the acid catalyst is added in amounts ranging from about 8% to
about 12% of the total weight of the polymerized resin. A more preferred
range of ingredients is as follows:
Coarse aggregate 45-60% by weight
Fine aggregate 30-40% by weight
Silica flour 2-10% by weight
Resin 8-12% by weight
More ~pecifically, the following combination of components yields
10 an excellent polymer concrete:
Coarfie aggregate 54% by weight
Fine aggregate (sand)36% by weight
Silica flour 10% by weight
Total 100%
Further, the furfuryl alcohol monomer is added in amounts of about 8-10% of
the total batch weight, depending upon compressive strengths required, the
more resin, the greater the compressive strengths. The preferred acid
catalyst is toluene sulfuric acid added as a 65% in water solution in amounts
of about 8% to about 12% of the total resin weight.
The procedure for forming the polymer concrete of the present inven-
tion is as follows:
(1) mix sand, coarse aggregate and silica flour thoroughly in an
electric mixer such as of the rotary type for several minutes to insure
complete blending, using batches of not more than 150 pounds at a time; (2)
add to the blended mix the acid catalyst in the correct proportions and mix
thoroughly for several minutes (2-4 minutes); (3) slowly add, while the
mixer is still rotating, the furfuryl alcohol monomer in the proportion shown
above; and (4) after mixing for about 2-4 minutes, pour into the form, screed
off and allowed to cure.
The function of each of the ingredients added to the polymer concrete
-14-
lZlB78~i
of the present invention can be characterized. The Eine and coar~e aggregates
serve as fillers and compression strength contributors after the monomer haM
polymerized and the polymerized resin has hardened. The silica flour serve3
to give a smooth finish on sides, top and bottom, filling voids left by the
fine aggregate. The polymerized furan resin, of course, serves as the binder
for the aggregates and silica Elour, holding the strength-giving mineral
aggregates together as a monolithic structure. The catalyst serves to polym-
erize the furfuryl alcohol monomer to form a solid binder. Other agents may
be added such as coupling agents to enhance the adherence of the resin binder
to the mineral aggregates. Pigments as well as other materials may be added
to control reaction time, ease oE handling, flow, etc. so long as such
materials do not adversely affect the strength of the Eormed polymer concrete.
Catalysts other than the 65% toluene sulfonic acid solution can be
used in the formulation of the polymer concrete so that the "set time" or
"field work time" can be extended. Such catalysts include more dilute solu-
tions of toluene sulfonic acid (35-45%); phosphoric acid; combinations of
toluene sulfonic acid and phosphoric acid; and z;nc chloride in water (5%
zinc chloride solution). If zinc chloride or other latent catalysts are used,
the concrete mix must be heated to temperatures of about 140 F. to 180 F.
to insure a proper and adequate cure.
Coarse aggregate which can be used in the polymer concrete of the
present invention can consist of gravel, stone or slag. All coarse aggre-
gates must be washed and dried to a moisture content of less than 1% and
preferably no more than one-half of 1% moisture. The coarse aggregate must
be free from disintegrated pieces, salt, alkali, carbonates, vegetable matter
-15-
~L218~86
and adherent coatings. The weight of extraneous sul)stances must not exceed
the following percentages:
Coal and lignite 1.00
Coal lumps 0.05
Soft fragments lO.00
Cinders and clinkers 0.50
Free she 118 1 . 00
Material passing No. 200 Sieve 1.75
In addition, the sum of the percentages of all of the substances above shall
not exceed 10%. Gravel used in the formulation of the polymer concrete must
be composed of clean, tough, durable quartz. Loss when the material is sub-
jected to the Los Angeles abrasion test should not be more than 50%. The
dry-rodded weight per cubic foot of the gravel should not be less than 95
pounds. The P~l must be 7.0 or less. Stone used in the formulation of the
polymer concrete should be clean, durable rock. The loss, when subjected to
the Los Angeles abrasion test should not exceed more than 45%. The dry-rodded
weight should not be less than 95 pounds per cubic foot and the pH must be
7.0 or less. Slag used must be clean, tough and durable. It must be air-
cooled blast-furnace slag only. It should be reasonably uni~orm in density
and quality9 and free from deleterious substances and contain not more than
1.5% sulfur. The dry-rodded weight should not be less than 70 pounds per
cubic foot, and the loss, when subjected to the Los Angeles abrasion test
should not exceed 45%. The pH again must not be greater than 7Ø Coarse
aggregates of different types cannot be mixed, nor used alternately in sec-
tions adjacent to each other or considered part of "one pour".
TABLE 6 below indicates a coarse aggregate gradation. As can be
seen from the TABLE, most of the coarse aggregate falls in the range of about
1 inch to no less than ~4 ASTM sieve size (.187 inch). Preferably, most of
the aggregrate is equal to or less than 3/8 inch and not less than .187 inch.
Preferably, 90% of the coarse aggregate should be in the range of one-half
inch to .187 inch.
-16-
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36
The combination oE Eine aggregateæ uæed in the formulation of the
of the polymer concrete oE the present invention should conæiæt of fiand
composed of hard, strong, durable uncoated grains of quartz, either quarry
pit material or material dredged from river bottoms. All fine aggregates
should be completely free Erom lumps, clay, soft or flakey particles, flalt,
alkali, organic matter, loam or extraneous æubstanceæ. Moisture content
should be no more than one-half of 1% and the pH must be 7.0 or less. The
fine aggregates should be well graded, from coarse to fine, and when tested
by means of laboratory sieves meet the following requirement, in percent of
10 total weight:
Total Retained On:
SlEVE ~0. PERCENT
4 0 - 5
8 0 - 15
16 3 - 35
30 - 75
65 - 95
100 93 - 100
No. 200-140 mesh silica flour used in the formulation oE the polymer
concrete preferably is of commercial grade, dry, bagged silica flour free of
carbonateæ.
Preferably, at least 75% of the fine aggregate has a size range
from about .047 inch to about .006 inch.
-18-
