CA1092743A - Polymer concrete having low binder levels - Google Patents
Polymer concrete having low binder levelsInfo
- Publication number
- CA1092743A CA1092743A CA304,687A CA304687A CA1092743A CA 1092743 A CA1092743 A CA 1092743A CA 304687 A CA304687 A CA 304687A CA 1092743 A CA1092743 A CA 1092743A
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- CA
- Canada
- Prior art keywords
- binder
- concrete
- polyester
- mixture
- polymer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B26/00—Compositions of mortars, concrete or artificial stone, containing only organic binders, e.g. polymer or resin concrete
- C04B26/02—Macromolecular compounds
- C04B26/10—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- C04B26/18—Polyesters; Polycarbonates
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Improved polymer bonded concrete is disclosed wherein the amount of polymer binder used may be reduced to amounts as low as 3 to 10% by weight of the concrete. The concrete has however high strength and other improved properties such as high modulum of elasticity, better fire resistance, low shrinkage on curing and the like and also very im-portantly, the cost is reduced. Preparation of the concrete is disclosed using an in situ polymerization process together with intense vibration of the monomer component-solids mix.
Improved polymer bonded concrete is disclosed wherein the amount of polymer binder used may be reduced to amounts as low as 3 to 10% by weight of the concrete. The concrete has however high strength and other improved properties such as high modulum of elasticity, better fire resistance, low shrinkage on curing and the like and also very im-portantly, the cost is reduced. Preparation of the concrete is disclosed using an in situ polymerization process together with intense vibration of the monomer component-solids mix.
Description
10927~3 This invention relates to polymer concretes. More particularly it relates to polymer concretes having very low polymer blnder levels.
Concretes manufactured with synthetic organic binders are known, the binders generally being resins of the epoxy, polyester, and melamine-formaldehyde types. These non-hydraulic concretes have superior propertles once the binders are cured and fused with the inorganic components to produce a hardened mass. They are used in the production of precast elements for architectural or engineering applications or for cast-in-place uses,where strength, water and chemical resistance or speed of cure are desirable. A
catalyst is generally added to the resinous component immediately before casting, the catalyzed resin is then added to the inorganic component and the resulting mix is placed in forms. Curing normally requires about 1 to 4 hours in the case of polyester binders.
Although polymer bonded concretes are now well-known, there are some ma~or drawbacks to the use of them. These drawbacks are high cost, low modulus of elasticity, poor fire resistance, limited surface effects that can be achieved for architectural purposes, high shrinkage on curing resulting in curling or cracking, high exothermic reaction on curing leading to internal stresses and poor processibility due to the viscous nature of the liquid phase used. All these disadvantages are the result of one difficulty and that is the inability to reduce the organic binder component below a level of about 10 - 15 percent by weight of the concrete without causing other serious problems such as low compressive and tensile strengths, poor resistance to wear and sensitivity to impact.
The use of low polymer binder levels in different types of compositions containing inorganic solids is known. For example, U.S.
patent 2,991, 267 discloses a granular material for use in making molds for metal casting. Sand is coated with a thermosetting resin such as a phenol- formaldehyde or melamine- ~ormaldehyde type and in order to obtain satisfactory binder distribution on the sand, the coating is carried out using a volatile solvent, a 1.
-~09Z743 slurry of the binder in a non-solvent or adherence of powdered binder to moistened sand. The amounts of binder necessary are disclosed as one half to flve percent by weight. When the mold is prepared, coatet sand of dlfferent grades is used and vibrated to ensure packing and heat or other treatment is then used to effect curing of the binder. Although very low resin amounts are disclosed, this reference is not helpful ~n respect of polymer concretes and decreasing the resin binder levels thereln, in that foundry molds are very porous articles and the strength considerations are not at all similar.
~ U.S. Patent 3,070,557 discloses aggregates and fillers bonded with polymers, which compositions are primarily intended to serve as paving compositions of the asphalt type. Although other uses are suggested for compositions no data are given as to strength measurements which would be of importance given the type of organic binders being used. The polymeric binders are high molecular weight linear thermoplastic polymers having cer-tain specific characteristics such as low softening point, being substantially uncrossllnked, melt viscosity of 100 - 30,000 cps and the like. Examples of the binders are polyolefins principally, and copolymers thereof. The proportions of the binder used are disclosed as 1 - 10% by weight of solid, preferably 2 - 8%. The method of application favored is hot plastic mixing, wherein the polymer is heated to 100 - 300F above its softening point and the inorganic solids are then mixed therewith. Even at those temperatures, the polymeric binder still has significantly high viscosity. This reference also is not of help in decreasing the level of the binders used in polymer concretes where high strength properties are required.
In fact, attempts have been made with polyester type concretes to mix the binder with the inorganic solids using a low level of binder by first heating the resin in order to reduce its viscosity. Theoretically this would enable mixing of low amounts of binder with the inorganic solids and still provide proper distribution throughout the composition. However, addition of catalyst, fillers, and sand on a continuous basis is required because of the increased reactivity of the heated resin. This necessitates complex machinery and results in relatively low delivery rates. Further-more, the viscosity reduction of the binder even on heating is not enough 10927~3 to achieve substantially lower resin levels.
Another reference wherein low binder levels are used with lnorganlc sollds ls V.S. Patent 3,243,388 which relates to a plastlc bonded concrete. However, although low binder levels are suggested the reference is concerned with compositions wherein the spaces between the mineral aggre-gates contain closed cell expanded or foamed plastlcs. Thermoplastic or thermosetting foamable resins are used and polymerization and foaming is carried out in the mold once the lnorganlc materlal has been mixed wlth the lng~redients. Generally polyurethane and polystyrene foams are illustrated. This type of "concrete" is a very light-weight material and the strength characteristics as compared to polymer concretes using non-foamed resins are completely different. Thus this reference is also not of help in enabllng reduction of blnder levels in high strength polymer concretes.
The coating of inorganic materlals with polymer by means of poly-merlzation of monomers carried out in the presence of the solids is known.
An example is U.S. Patent 3,971,753 but this patent does not deal with polymer bonded concrete but rather with fillers to be incorporated in polymer compositions. It has nothing to do with the problems attendant on attempt-ing to lower the total polymer content of a polymer bonded concrete.
The specific problem of binder level in polymer bonded concretes has been dealt with in U.S. Patent 3,801,536. This reference discloses that the viscosity of the polymeric binder, i.e. epoxy or polyester resin, for use with various aggregates and fillers can be affected by the use of a micronic inorganic filler having particle size below two microns and high shape regularity. This material is used in an amount of about 25 - 75% by weight of the binder and enables reduction of the proportion of resin in the eventual composition, but with proper distribution of the binder through-out the other solid materials. The micronic material apparently most suitable and particularly illustrated is titanium dioxide, especlally a mixture of anatase and rutile, although iron oxldes are also suggested. The references dlscloses that wlth thls material the amount of resin which can be --` 109Z743 used in the case of polyester resins is lowered to 7 - 13% by weight of the composition and 2 - 7% by weight with epoxy resins. The main dis-advantage to the use of this method of lowering binder leve1s in polymer concrete is that the micron~c fillers required are 2 to 4 times as expensive as the resin binder by volume. These cost considerations mitigate against the use of these materials.
It has now been found that very low binder levels in polymer bonded concrete can be achieved by a completely different method. This is done by~mixing certain monomeric materials with the inorganic components rather than only formed polymers or prepolymers as binder, together with polymeriza~ion initiator and allowing polymerization to occur as the setting process. The exceptionally low viscosity of the liquid phase permits the mixing in of enough sand, fillers, and aggregates to obtain binder levels of 5 - 10% by weight and as low as 3%.Optimum distribution of the binder material and resultant strength of the concrete product is also aided by intense vibration of the mixed components to obtain maximum packing of the solids either before or during the setting process. Setting is accelerated or initiated by the application of heat, use of promotors and the like.
Thus, the present invention provides a polymer concrete having ; 20 high strength characteristics comprising an aggregate consisting of sand, stone or gravel or mixtures thereof and an organic binder in an amount ofabout 3 to about 10% by weight of said concrete, said organic binder consisting of polymer formed in situ from one or morec~ ethylenically unsaturated monomers of the group of styrene, styrene derivatives, Cl-8 alkyl esters of acrylic or methacrylic acids, and divinyl benzene, or a low viscosity solution of an unsaturated polyester in said monomers, said solution containing monomer in excess of that required for cross-linking the polyester.
The invention also provides a process for the preparation of a polymer bonded concrete of low binder content which comprises (1) mixing an aggregate consisting of sand, stone, or gravel or mixtures thereof with, as binder components, a) one or more ,~-ethylenically unsaturated monomers of the group of styrene, styrene derivatives, Cl 8 alkyl esters of acrylic or methacrylic acids,or divinyl benzene, or an unsaturated polyester dissolved in one or more of saidmonomers, the solution of monomer and polyester being of low viscosity and con-taining monomer in excess of that required for cross-linking purposes, and b) a free radical polymerization initiator, to form a mixture of said aggregate with said binder components;
Concretes manufactured with synthetic organic binders are known, the binders generally being resins of the epoxy, polyester, and melamine-formaldehyde types. These non-hydraulic concretes have superior propertles once the binders are cured and fused with the inorganic components to produce a hardened mass. They are used in the production of precast elements for architectural or engineering applications or for cast-in-place uses,where strength, water and chemical resistance or speed of cure are desirable. A
catalyst is generally added to the resinous component immediately before casting, the catalyzed resin is then added to the inorganic component and the resulting mix is placed in forms. Curing normally requires about 1 to 4 hours in the case of polyester binders.
Although polymer bonded concretes are now well-known, there are some ma~or drawbacks to the use of them. These drawbacks are high cost, low modulus of elasticity, poor fire resistance, limited surface effects that can be achieved for architectural purposes, high shrinkage on curing resulting in curling or cracking, high exothermic reaction on curing leading to internal stresses and poor processibility due to the viscous nature of the liquid phase used. All these disadvantages are the result of one difficulty and that is the inability to reduce the organic binder component below a level of about 10 - 15 percent by weight of the concrete without causing other serious problems such as low compressive and tensile strengths, poor resistance to wear and sensitivity to impact.
The use of low polymer binder levels in different types of compositions containing inorganic solids is known. For example, U.S.
patent 2,991, 267 discloses a granular material for use in making molds for metal casting. Sand is coated with a thermosetting resin such as a phenol- formaldehyde or melamine- ~ormaldehyde type and in order to obtain satisfactory binder distribution on the sand, the coating is carried out using a volatile solvent, a 1.
-~09Z743 slurry of the binder in a non-solvent or adherence of powdered binder to moistened sand. The amounts of binder necessary are disclosed as one half to flve percent by weight. When the mold is prepared, coatet sand of dlfferent grades is used and vibrated to ensure packing and heat or other treatment is then used to effect curing of the binder. Although very low resin amounts are disclosed, this reference is not helpful ~n respect of polymer concretes and decreasing the resin binder levels thereln, in that foundry molds are very porous articles and the strength considerations are not at all similar.
~ U.S. Patent 3,070,557 discloses aggregates and fillers bonded with polymers, which compositions are primarily intended to serve as paving compositions of the asphalt type. Although other uses are suggested for compositions no data are given as to strength measurements which would be of importance given the type of organic binders being used. The polymeric binders are high molecular weight linear thermoplastic polymers having cer-tain specific characteristics such as low softening point, being substantially uncrossllnked, melt viscosity of 100 - 30,000 cps and the like. Examples of the binders are polyolefins principally, and copolymers thereof. The proportions of the binder used are disclosed as 1 - 10% by weight of solid, preferably 2 - 8%. The method of application favored is hot plastic mixing, wherein the polymer is heated to 100 - 300F above its softening point and the inorganic solids are then mixed therewith. Even at those temperatures, the polymeric binder still has significantly high viscosity. This reference also is not of help in decreasing the level of the binders used in polymer concretes where high strength properties are required.
In fact, attempts have been made with polyester type concretes to mix the binder with the inorganic solids using a low level of binder by first heating the resin in order to reduce its viscosity. Theoretically this would enable mixing of low amounts of binder with the inorganic solids and still provide proper distribution throughout the composition. However, addition of catalyst, fillers, and sand on a continuous basis is required because of the increased reactivity of the heated resin. This necessitates complex machinery and results in relatively low delivery rates. Further-more, the viscosity reduction of the binder even on heating is not enough 10927~3 to achieve substantially lower resin levels.
Another reference wherein low binder levels are used with lnorganlc sollds ls V.S. Patent 3,243,388 which relates to a plastlc bonded concrete. However, although low binder levels are suggested the reference is concerned with compositions wherein the spaces between the mineral aggre-gates contain closed cell expanded or foamed plastlcs. Thermoplastic or thermosetting foamable resins are used and polymerization and foaming is carried out in the mold once the lnorganlc materlal has been mixed wlth the lng~redients. Generally polyurethane and polystyrene foams are illustrated. This type of "concrete" is a very light-weight material and the strength characteristics as compared to polymer concretes using non-foamed resins are completely different. Thus this reference is also not of help in enabllng reduction of blnder levels in high strength polymer concretes.
The coating of inorganic materlals with polymer by means of poly-merlzation of monomers carried out in the presence of the solids is known.
An example is U.S. Patent 3,971,753 but this patent does not deal with polymer bonded concrete but rather with fillers to be incorporated in polymer compositions. It has nothing to do with the problems attendant on attempt-ing to lower the total polymer content of a polymer bonded concrete.
The specific problem of binder level in polymer bonded concretes has been dealt with in U.S. Patent 3,801,536. This reference discloses that the viscosity of the polymeric binder, i.e. epoxy or polyester resin, for use with various aggregates and fillers can be affected by the use of a micronic inorganic filler having particle size below two microns and high shape regularity. This material is used in an amount of about 25 - 75% by weight of the binder and enables reduction of the proportion of resin in the eventual composition, but with proper distribution of the binder through-out the other solid materials. The micronic material apparently most suitable and particularly illustrated is titanium dioxide, especlally a mixture of anatase and rutile, although iron oxldes are also suggested. The references dlscloses that wlth thls material the amount of resin which can be --` 109Z743 used in the case of polyester resins is lowered to 7 - 13% by weight of the composition and 2 - 7% by weight with epoxy resins. The main dis-advantage to the use of this method of lowering binder leve1s in polymer concrete is that the micron~c fillers required are 2 to 4 times as expensive as the resin binder by volume. These cost considerations mitigate against the use of these materials.
It has now been found that very low binder levels in polymer bonded concrete can be achieved by a completely different method. This is done by~mixing certain monomeric materials with the inorganic components rather than only formed polymers or prepolymers as binder, together with polymeriza~ion initiator and allowing polymerization to occur as the setting process. The exceptionally low viscosity of the liquid phase permits the mixing in of enough sand, fillers, and aggregates to obtain binder levels of 5 - 10% by weight and as low as 3%.Optimum distribution of the binder material and resultant strength of the concrete product is also aided by intense vibration of the mixed components to obtain maximum packing of the solids either before or during the setting process. Setting is accelerated or initiated by the application of heat, use of promotors and the like.
Thus, the present invention provides a polymer concrete having ; 20 high strength characteristics comprising an aggregate consisting of sand, stone or gravel or mixtures thereof and an organic binder in an amount ofabout 3 to about 10% by weight of said concrete, said organic binder consisting of polymer formed in situ from one or morec~ ethylenically unsaturated monomers of the group of styrene, styrene derivatives, Cl-8 alkyl esters of acrylic or methacrylic acids, and divinyl benzene, or a low viscosity solution of an unsaturated polyester in said monomers, said solution containing monomer in excess of that required for cross-linking the polyester.
The invention also provides a process for the preparation of a polymer bonded concrete of low binder content which comprises (1) mixing an aggregate consisting of sand, stone, or gravel or mixtures thereof with, as binder components, a) one or more ,~-ethylenically unsaturated monomers of the group of styrene, styrene derivatives, Cl 8 alkyl esters of acrylic or methacrylic acids,or divinyl benzene, or an unsaturated polyester dissolved in one or more of saidmonomers, the solution of monomer and polyester being of low viscosity and con-taining monomer in excess of that required for cross-linking purposes, and b) a free radical polymerization initiator, to form a mixture of said aggregate with said binder components;
(2) casting said mixture;
(3) subjecting said mixture to intense vibration to pack solids therein to occupy the minimum possible volume; and
(4) allowing said monomers to polymerize and set to produce said polymer bonded concrete.
In more particular aspects, the invention provides a process for the ?
preparation of a polymer bonded concrete containing from 3 to less than 10% of organic binder material, which process comprises:
(1) mixing an aggregate consisting of sand, stone or gravel or mixtures thereof with binder components comprising (a) an unsaturated polyester resin dissolved in styrene monomer, :
the solution being of low viscosity and containing additional monomer in excess of that required far cross-linking of the polyester, the additional monomer being selected from the group styrene, methyl methacrylate and butylacrylate, and (b) a free radical polymerization initiator, to form a mixture of the aggregate and the binder components;
(2) casting the mixture;
(3) subjecting the mixture to intense vibration to pack solids therein to occupy the minimum possible volume and substantially eliminate voids;and (4) causing the monomers to polymerize by the application of heat D
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` 10927~3 to produce the polymer bonded concrete;
and a process for the preparation o a polymer bonded concrete contain-ing from 3 to less than 7% of organic binder material, which process comprises:
(1) mixing an aggregate consisting of sand, stone or gravel or mixtures thereof with binder components comprising (a) methyl methacrylate monomer, and (b) a free radical polymerization initiator, to form a mixture of the aggregate and the binder components;
(2) casting the mixture;
(3) subjecting the mixture to intense vibration to pack solids therein to occupy the minimum possible volume and substantially eliminate voids, and (4) causing the monomers to polymerize by the application of heat to produce the polymer bonded concrete.
The ability to use monomers and in situ polymerization (not only a cross-linking process) to obtain a polymer bonded concrete of superior properties is completely unexpected. One would expect high shrinkage to occur as the mono-mers used inherently shrink far more during polymerization than occurs during curing of, for example, a polyester resin used alone as binder. For instance, the shrinkage that occurs in polymerization of methyl methacrylate to polymethyl methacrylate is 20-22%. In fact, however, when the method according to the present invention is used, the retraction of the concrete is less than occurs in the preparation of conventional polymer bonded concretes. Furthermore, the stress cracking that is normally associated with the exotherm produced by the curing of high-resin concretes is absent. The concrete also "places" better than hydraulic concrete, allowing casting in molds as thin as ~-inch. Furthermore, standard concrete mixing and placing equipment may be used.
Because of the decreased levels o binder which may be used in the concrete according to the present invention, the total cost of the concrete often can be halved with no untoward effects on mechanical properties. For - 5a -:
.
109Z~743 example,, a formulation containing 3.5 percent unsaturated polyester dissolved in styrene (72:28) by weight), 3.1 percent methyl-eth4cryL~te, 0.08% initiator and 93% graded silica fillers, sand and aggregates has provided a concrete of 2750 p.s.l. in flexion, 13,500 p.s.i. in compression strength, having resistance to at least 50 cycles of freeze and thaw and absorbing 0.1% water. The modulus of elasticity, 6.6 X 106, i9 at least twice as high as that of conventional polyester bonded concretes. The weathering resistance is also improved in that a concrete such as aforemention-ed exhibited no changed in appearance after 2500 hours in a weatherometer.
The binder is the only flammable component in polymer bonded concretes and as according to the present invention the proportion of the binder component is considerably reduced, the fire resistance is greatly improved. Furthermore, replacement of conventional fillers of smaller size with certain materials even further improves the fire resistant properties as will be detailed later herein.
The aggregates which can be used in the present process are sands, stone and gravel which are normally used for making concrete with hydraulic binders. The aggregates may be screened or crushed, preferably with not too many fines.
Fillers which are comminuted solids can be added to the actual aggregates as granulated material of particle size less than the aggregates.
Sllica is advantageously used because of its low price, low porosity and relatively great hardness. Examples of suitable types of silica are silica flour and Ottawa silica. Also among fillers which may be used are treated and untreated calcium carbonates. The percentage of the filler or extender which is used is determined for any given aggregate by a technique analagous to that used in the production of hydraulic cements and mortars. It consists for a given aggregate in testing various proportions of aggregates and extend-er in a system of the binder composition of interest. The quantity of the extender chosen will be that which corresponds substantially to the maximum 6.
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of resistance to compression and of flexion. The fillers mentioned are not intended to be limiting as any fillers known ln the art of concrete J~nu-facture may be used.
Other materials may be added, as for example titanium dioxide or iron oxides or other materials for pigmentation.
It has been found that by replacement of smaller size fillers (e.g. 44 - 220 microns) with certain compounds, fire retardancy of the products is greatly increased over and above that achieved by reduction in the amount of binder used. These compounds may be any powdered sub-1~ stance which releases water of crystallization at high temperatures as for example alumina trihydrate, tricalcium aluminate hexahydrate and zinc borate. The amount of such materials which is required to provide maximum fire retardancy is in general about twice the amount of resin binder that is used. Thus in the conventional polymer concretes pro-hibitive amounts of these materials must be used, but with the concretes according to the present invention having low polymer binder content there is a corresponding decrease in the amount of fire retardant compound which i9 necessary to obtain maximum retardancy. Generally levels of 20 - 200% by weight based on binder greatly improves fire resistance of the concrete.
It has already been indicated that the monomers which may be used to form the binders according to the present invention are ~,~ -ethylen-ically unsaturated monomers, i.e. styrene and styrene derivatives, divinyl benzene and Cl-8 alkyl esters of acrylic and methacrylic acids. Examples of these monomers are styrene itself, lower alkyl substituted styrenes as for instance ~ -methyl styrene and vinyl toluene, divinyl benzene, methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate and the like. These monomers may be used alone or in combination and the preferred monomers, particularly from the point of view 109Z~743 of cost, are styrene, methyl methacrylate and butyl acrylate. Suitably, others of the monomers may be combined with the preferred monomers to modlfy the properties of the binder and as such can be used in minor amounts.
Also other monomers in addition to those mentioned and cross-linking agents may be included in relatively low proportions to alter properties of the binder, as for instance to improve adhesion or increase glass transition temperature. Examples of these monomers and cross-linking agents are acrylic acid, methacrylic acid, 1,3-butylene dimeth-acrylate, trimethylolpropane trimethacrylate, die~hyl phthalate, dibutyl phthalate and diallyl phthalate.
The foregoing monomers can be used as such or can be used to dissolved a certain proportion of unsaturated polyester. These unsaturated polyesters are condensation products of polyalcohols and unsaturated dibasic acids and are general purpose medium reactive resins conventionally used in the polymer concrete and fibre glass fields as binders. Examples are Palatal*H-170 (obtainab~e from BASF Canada Ltd) and Laminac* 4193 (ob-tainable from Cyanamid of Canada which are unsaturated polyester resins dissolved in styrene, there being incorporated in the resin about 1 part 2a of maleic anhydride for every 2 parts of styrene. Paraplex* P-444A
(obtainable from Rohm ~ Haas Company Canada Ltd.) is a similar suitable unsaturated polyester.
It is known to add material such as styrene to unsaturated ~ -polyester resins and in fact they are supplied by chemical suppliers diluted with sufficient styrene for eventual cross-linking of the polyester.
The proportions supplied are usually about 70 parts by weight polyester to 30 parts by weight styrene. The viscosity of such diluted resins is still far greater than 1000 cps. By the further dilution according to the present inventlon with monomers as aforementioned viscosities of perhaps 50 cps down to less than 1 cps are obtained. Such diluted polyesters * Trade Mark ,' ' ' , `
~09:2743 provide more monomer than is required for cross-linking of the polyester and when used according to the present invention polymerization of that monomer occurs as well as the cross-linking reaction. Obvlouoly when an unsaturated polyester resin is not used, the viscosity of the monomer components is negligible when compared to the use of preformed resin binders and cross-linking is not involved.
For the purposes of the present invention it has been fount possible to use proportions of unsaturated polyester resin dissolved in monomers so long as the viscosity of the solution in the monomers does not exceed about 50 cps. In terms of proportion by weight, the polyester resin can constitute up to about 50% by weight of the binder components, and is preferably 40% by weight or less.
As indicated previously the amount of binder component (a) which can be used according to the present invention is generally between 5 and 10% by weight of the composition, but even lower proportions are suitably down to about 3 %. The low viscosity of the liquid organic phase permits mixing in of high levels of aggregates, fillers and sand and other inorganlc components and the low surface tension of the liquid phase allows intimate contact between the organic particles. Because of the low proportions of liquid used, it is not so much the liquid phase that provides the characteristics of curing and of the final product but rather a product is provided which is a nearly inorganic, nearly mono-lithic structure with particles of sand and aggregate intimately adhering to each other. The final product has in fact more of the characteristics of granite or stone than plastic, or for that matter even hydraulic concrete.
The amount of binder can be increased somewhat above 10% but ~`
if increased too much then problems arise in obtaining a uniform concrete and the improved properties obtainable with the lower binder levels are sacrificed.
30 ` The polymerization initiators which are added according to the process of the present invention are free radical type initiators which will effect polymerization of the monomers, and where applicable, cross-linking of the polyester resins used. These initiators may be either those which are active at room temperature or at increased temperatures. An example for use at room temperature is benzoyl peroxide together with nitrogen containing promoters such as N,N-diethyl-m-toluidine and N,N-dimethyl-aniline. An example of an initiator for use at elevated temperature is bis-4-tertiary-butyl-cyclohexyl peroxydicarbonate. The use of heat activated initiators and heat during setting of the concrete i9 of ad-vantage in that it permits a longer pot-life of the fresh concrete mix.
Other examples of appropriate initiators will immediately occur to those skilled in the art. The proportions of initiator will generally be 0.1 to 5% by weight of other binder components.
As indicated previously standard concrete mixing and placing equipment may be used for the concrete according to the invention. For precast concrete components, the molds used are preferably closed molds although open molds are possible. The reason for this is partly because of volatility of the monomers when heat is used to effect setting and also -~
the use of closed molds prevents warping because heat can be applied from both sides and a more uniform polymerization obtained. If closed molds are used, it is not necessary that the ld be completely closed and by closed molds can be meant as well a mold with up to 10 - 30% of the concrete surface area being exposed.
It is standard practice in the manufacture of regular precast concrete to vibrate ~he concrete in order to place it and bring to the surface any air entrapped while mixing or pouring. The use of vibration in the process of the present invention is essential for those reasons and also for another, that is the achievement of minimum volume occupied by the aggregates or placement of the aggregates without voids. By reducing the viscosity of the liquid phase preferably to something of the order of less than 1 centipoise with concomitant reduction in surface tension the aggregates can settle freely on vibration and orient themselves in what inevitably turns out to be the most compact placement. This of .
10.
' ,~ ~.
109'~743 course cannot be achieved with viscous binders. Since this procedure allows solids to impinge on solids, the shrinkage normally a6soci~t4d with increasing monomer level and conversion to polymer is not experienced.
In the case of hydraulic concrete, over-vibration leads to segregation of the mix which is undesirable. In the present process over-vibration can be routinely used to ensure placing of the aggregates in the desired configuration.
Various vibrating devices can be used depending on the manner of manùfacture of the concrete. For example with molds for precast concrete table vibrators can be used whereas for cast-in-place applications internal vibrating devlces are appropriate. In fact any type of vibration may be used and any frequency, even mechanical shock, as long as it is intense. The energy requirements are not dependent on frequency and the amount of vibration that is to be used is determined empirically and is such as is sufficient to remove significant amounts of voids. In other words the spaces or gaps between aggregate particles are reduced to a minimum.
Once the concrete mixture has been cast and vibrated, the time required for setting will of course depend on the particular ini-tlator used and whether or not heat is applied. The time required may be anything from 5 minutes up to 3 hours or longer and the temperature may be from room temperature up to 200F or higher.
Reinforcing materials used in conventional concrete mixes may also be used according to the present invention. These may be for example reinforcing bars or steel mesh. Also steel fibres may be used in ~ -the present compositions and can be merely mixed in with the other com-ponents, which is unlike hydraulic concretes wherein the steel fibres on mixing tend to agglomerate. Such reinforcment improves the tensile strength and impact resistance of the concrete.
The polymer bonded concretes according to the present invention can be modified as to surface appearance for various architectural uses.
11.
~092743 The surface of the concrete can be treated or etched with any solvent for the polymer binder used so that an exposed aggregate effect i~ obtalnst.
A particularly useful solvent for polymethacrylate, polyacrylates or polystyrene is methylene chloride. Surface treatment of this type i8 normally produced in hydraulic concretes by etching with acids, retarding the surface cure of the concrete and/or by sand blasting.
A plastic-like finish on the concrete may be obtained in precast structures by applying a coating of pigmented resin in the mold prior to casting of the concrete. This surface coating adheres per- ~ -lQ manently to the concrete product. Examples of such resins are Palatal*
H-170 and Gel-Kote* (available from Glidden Company).
The following examples are intended to illustrate the present invention but are not to be limiting to the scope thereof.
In all the examples the aggregates used were added to a con-ventional pan-type mixer, the liquid ingredients except for initiator then added, followed by the other dry ingredients and finally the initiator.
Mixing was continued for two minutes and the mix then transferred to a closed 30 square foot mold. Vibration was carried out for two minutes using a 1~ horse power reciprocal vibrator operating at a frequency of 3450 rpm.
The conditions of curing or setting are detailed in each example.
Example 1 A polymer concrete according to the invention was prepared using the following components:
Polyester Resin 72% Styrene 28% (Palatal*H-170) 3.5%
Methyl Methacrylate 3.1%
Bis-4-Tertbutylcyclohexyl Peroxydicarbonate 0.08%
- Silica Flour ( >200 Mesh) 12.6%
Ottawa Silica (27 Mesh) 21.2%
Round Quartz Aggregates (1/8" - 3/8") 58.8%
Titanium Dioxide 0.8%
* Trade Mark 109~ 3 % Organic: 6.7 Heat Cure: (~ hour at 175F) Thickness of Casting: ~ 3/4"
Compressive Strength: 13,500 p.s.i. (ASTM C39-73), Flexural Strength: 2,750 p.s.i, (ASTM C78-75) Modulus of Elasticity: 6.6 X 106p.s.i.(ASTM C469-65) Example 2 The following components were used in preparation of a polymer concrete according to the invention:
Methyl Methacrylate 5.75%
Bis-4-Tertbutylcyclohexyl Peroxydicarbonate 0.05%
Titanium Dioxide 0.25%
Calcium Carbonate 250 Mesh + 12.00%
Calcium Carbonate 50 - 500 mesh 14.00%
Aggregates 1/8" - 1" 67.20%
% Organic: 5.8%
Heat Cure: (1 hour at 160F) Thic~ness of Casting: ~ 2" ' Example 3 The fo}lowing components were used:
Polyester resin 72%, Styrene 28% (Palatal*H-170) 3.20%
Butyl Acrylate 1.60%
, Methyl Methacrylate 1.60%
Silica Flour * (200 Mesh) 12.00%
Ottawa Silica (27 Mesh) 32.00%
Round Quartz Aggregates (1/8" - 3/4") 49.00%
Titanium Dioxide 0.13%
N-N-Diethyl-m-Toluidine 0.04%
N,N-Dimethylaniline 0.08%
Benzoyl Peroxide 70% (Granules) 0.25X
-: ~
~0!9Z743 % Organic: 6.77 Room Temperature Cure: (3 hours at 70F) Thickness of Casting: ~ 2"
* 7.8% retained on 200 mesh; 12.9% retained on 270 mesh;
11.1% retained on 325 mesh, pan: 66.7%.
Example 4 -This concrete was prepared from the following:
Polyester Resin 72%, Styrene 28%(Palatal*H-170) 2.5%
la Methyl Methacrylate 2.5%
Bis-4-Tertbutylcyclohexyl Peroxydicarbonate 0.1%
Silica Flour ( > 200 Mesh) 12.9%
Ottawa Flour (27 Mesh) 21.9%
Round Quartz Aggregates (1/8" - 3/4") 59.7%
Titanium Dioxide 0.4%
% Organic: 5.1 Heat Cure: (3/4 hour at 175 F) Thickness of Casting: ~ 2"
Thls example was also repeatèd using only styrene in place r 20 of methyl methacrylate with comparable results.
' Example 5 The following were used to prepare a concrete mix:
Polyester resin 72% Styrene 28%(Palatal* H-170) 3.3%
Methyl Methacrylate 2.7%
` Bis-4-Tertbutylcyclohexyl Peroxydicarbonate 0.6%
Silica Flour ( ~200 Mesh) 10.0%
Ottawa Silica (27 Mesh) 15.0%
Round Quartz Aggregates (1/8" - 3/8") 68.5%
Iron Oxide Color 0.5%
14.
.. .. . . . . . .
., ~ - . . - . :
~09~43 % Organic: 6.1 Heat Cure: 15 Minutes at 200 F
Thickness of Casting:
Example 6 The following ingredients were mixed and cured:
Polyester resin 72%, Styrene 28% (Palatal*H-170) 2.9%
Methyl Methacrylate 2.9%
Bis-4-Tertbutylcyclohexyl Peroxydicarbonate 0.06%
Silica Flour ( >200 Mesh) 3.8%
Aluminum Hydrate (Average 100 Mesh) 10.0%
Ottawa Silica (27 Mesh) 16.2%
Round Quartz Aggregates (1/8" - 1/2") 64.0%
Titanium Dioxide 0.2%
% Organic: 5.9 Heat Cure: 1 Hour at 165F
Thickness of Casting: 2"
Example 7 A concrete was prepared from the following:
Polyester Resin 72% Styrene 28% (Palatal*H-170) 3.3%
Methyl Methacrylate 3.3%
Bis~4~Tertbutylcyclohexyl Peroxydicarbonate 0.1%
Silica Flour ( ~200 Mesh) 6.0%
Aluminum Hydrate (Average 100 Mesh) 13.4%
Ottawa Silica (27 Mesh) 15.2%
- Round Quartz Aggregates (1/8" - 1/2") 57.46%
Titanium Dioxide 0.14%
Molybdate Orange 1.12%
; "~
% Organic: 6.7 Heat Cure: ~ Hour at 175F
Thickness of Casting: < 2"
The polymer concretes of Examples 2 - 7 had properties very similar to those of the concrete of Example l,for instance compressive strengths of the order of 13,500 psi.
It was found that the properties of the concretes of the foregoing Examples did not vary to any significant degree for the binder proportions specified.
As an indicationof the fire resistant properties of polymer concretes as illustrated in Examples 6 and 7, a concrete made from the components as listed in Example 7 but without the molybdate orange coloring was found not to give off smoke or flame during decomposition by a 2500F heat source. Smoke emission according to ASTM D2843 was 1% while ~ --a test for fire resistance (ASTM D2863) resulted in an oxygen lndex of over 80.
All of the foregoing examples of polymer bonded concretes accorting to the invention may be used for precast panels for-fascia panels for buildings having thicknesses of 3/8 to 4'i, patio slabs~ concrete flower boxes, garden furniture, load bearing or non-load bearing sandwich panels using urethane foam sandwich between two -slabs of polymer concrete ;~` adhered both mechanically and chemically, wall cladding 3~8 to 1 inch thick to replace conventional lath and stucco systems, plywood and aluminum and steel siding, and the like.
- The polymer bonded concretes of examples 1, 3, 4 and 5 are particularly suitable for the manufacture of drain, sewer and other pipes because of chemical and abrasion resistance. These polymer concretes -are also of use for chemically resistant articles such as pump motor boxes, storage tanks and basis, floor slabs and tiles.
- 16.
`- 109~7~3 The polymer concrete of Example 1 has been used in the form of panels to protect the sides, undersides, or supporting plll~rs of elevated highways because of its extremely high chemical resistance.
This concrete has also been used as permanent, white, impervious forms for highway median strips, these forms being thin shells utilizlng regular hydraulic concrete as filler.
The polymer concrete of example 4 is abrasion resistant and is particularly suitable for the manufacture of railroad ties and tracks for rubber tired subway cars.
la The polymer concretes of examples 6 and 7 are particularly suitable for the manufacture of fire resistant panels and the like because of the low binder content and inclusion of aluminum hydrate.
`
In more particular aspects, the invention provides a process for the ?
preparation of a polymer bonded concrete containing from 3 to less than 10% of organic binder material, which process comprises:
(1) mixing an aggregate consisting of sand, stone or gravel or mixtures thereof with binder components comprising (a) an unsaturated polyester resin dissolved in styrene monomer, :
the solution being of low viscosity and containing additional monomer in excess of that required far cross-linking of the polyester, the additional monomer being selected from the group styrene, methyl methacrylate and butylacrylate, and (b) a free radical polymerization initiator, to form a mixture of the aggregate and the binder components;
(2) casting the mixture;
(3) subjecting the mixture to intense vibration to pack solids therein to occupy the minimum possible volume and substantially eliminate voids;and (4) causing the monomers to polymerize by the application of heat D
. .... . .. : .~ ~ . ~ , .. ... ... -.. , ..... - ,'.. ~ . ~ ~ .. . ..
. .. . . . .
.. . ~ . . . .. . .
`~ ~
` 10927~3 to produce the polymer bonded concrete;
and a process for the preparation o a polymer bonded concrete contain-ing from 3 to less than 7% of organic binder material, which process comprises:
(1) mixing an aggregate consisting of sand, stone or gravel or mixtures thereof with binder components comprising (a) methyl methacrylate monomer, and (b) a free radical polymerization initiator, to form a mixture of the aggregate and the binder components;
(2) casting the mixture;
(3) subjecting the mixture to intense vibration to pack solids therein to occupy the minimum possible volume and substantially eliminate voids, and (4) causing the monomers to polymerize by the application of heat to produce the polymer bonded concrete.
The ability to use monomers and in situ polymerization (not only a cross-linking process) to obtain a polymer bonded concrete of superior properties is completely unexpected. One would expect high shrinkage to occur as the mono-mers used inherently shrink far more during polymerization than occurs during curing of, for example, a polyester resin used alone as binder. For instance, the shrinkage that occurs in polymerization of methyl methacrylate to polymethyl methacrylate is 20-22%. In fact, however, when the method according to the present invention is used, the retraction of the concrete is less than occurs in the preparation of conventional polymer bonded concretes. Furthermore, the stress cracking that is normally associated with the exotherm produced by the curing of high-resin concretes is absent. The concrete also "places" better than hydraulic concrete, allowing casting in molds as thin as ~-inch. Furthermore, standard concrete mixing and placing equipment may be used.
Because of the decreased levels o binder which may be used in the concrete according to the present invention, the total cost of the concrete often can be halved with no untoward effects on mechanical properties. For - 5a -:
.
109Z~743 example,, a formulation containing 3.5 percent unsaturated polyester dissolved in styrene (72:28) by weight), 3.1 percent methyl-eth4cryL~te, 0.08% initiator and 93% graded silica fillers, sand and aggregates has provided a concrete of 2750 p.s.l. in flexion, 13,500 p.s.i. in compression strength, having resistance to at least 50 cycles of freeze and thaw and absorbing 0.1% water. The modulus of elasticity, 6.6 X 106, i9 at least twice as high as that of conventional polyester bonded concretes. The weathering resistance is also improved in that a concrete such as aforemention-ed exhibited no changed in appearance after 2500 hours in a weatherometer.
The binder is the only flammable component in polymer bonded concretes and as according to the present invention the proportion of the binder component is considerably reduced, the fire resistance is greatly improved. Furthermore, replacement of conventional fillers of smaller size with certain materials even further improves the fire resistant properties as will be detailed later herein.
The aggregates which can be used in the present process are sands, stone and gravel which are normally used for making concrete with hydraulic binders. The aggregates may be screened or crushed, preferably with not too many fines.
Fillers which are comminuted solids can be added to the actual aggregates as granulated material of particle size less than the aggregates.
Sllica is advantageously used because of its low price, low porosity and relatively great hardness. Examples of suitable types of silica are silica flour and Ottawa silica. Also among fillers which may be used are treated and untreated calcium carbonates. The percentage of the filler or extender which is used is determined for any given aggregate by a technique analagous to that used in the production of hydraulic cements and mortars. It consists for a given aggregate in testing various proportions of aggregates and extend-er in a system of the binder composition of interest. The quantity of the extender chosen will be that which corresponds substantially to the maximum 6.
-: . , , ~ . - :
- :
, . , . . ~ . .
`
of resistance to compression and of flexion. The fillers mentioned are not intended to be limiting as any fillers known ln the art of concrete J~nu-facture may be used.
Other materials may be added, as for example titanium dioxide or iron oxides or other materials for pigmentation.
It has been found that by replacement of smaller size fillers (e.g. 44 - 220 microns) with certain compounds, fire retardancy of the products is greatly increased over and above that achieved by reduction in the amount of binder used. These compounds may be any powdered sub-1~ stance which releases water of crystallization at high temperatures as for example alumina trihydrate, tricalcium aluminate hexahydrate and zinc borate. The amount of such materials which is required to provide maximum fire retardancy is in general about twice the amount of resin binder that is used. Thus in the conventional polymer concretes pro-hibitive amounts of these materials must be used, but with the concretes according to the present invention having low polymer binder content there is a corresponding decrease in the amount of fire retardant compound which i9 necessary to obtain maximum retardancy. Generally levels of 20 - 200% by weight based on binder greatly improves fire resistance of the concrete.
It has already been indicated that the monomers which may be used to form the binders according to the present invention are ~,~ -ethylen-ically unsaturated monomers, i.e. styrene and styrene derivatives, divinyl benzene and Cl-8 alkyl esters of acrylic and methacrylic acids. Examples of these monomers are styrene itself, lower alkyl substituted styrenes as for instance ~ -methyl styrene and vinyl toluene, divinyl benzene, methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate and the like. These monomers may be used alone or in combination and the preferred monomers, particularly from the point of view 109Z~743 of cost, are styrene, methyl methacrylate and butyl acrylate. Suitably, others of the monomers may be combined with the preferred monomers to modlfy the properties of the binder and as such can be used in minor amounts.
Also other monomers in addition to those mentioned and cross-linking agents may be included in relatively low proportions to alter properties of the binder, as for instance to improve adhesion or increase glass transition temperature. Examples of these monomers and cross-linking agents are acrylic acid, methacrylic acid, 1,3-butylene dimeth-acrylate, trimethylolpropane trimethacrylate, die~hyl phthalate, dibutyl phthalate and diallyl phthalate.
The foregoing monomers can be used as such or can be used to dissolved a certain proportion of unsaturated polyester. These unsaturated polyesters are condensation products of polyalcohols and unsaturated dibasic acids and are general purpose medium reactive resins conventionally used in the polymer concrete and fibre glass fields as binders. Examples are Palatal*H-170 (obtainab~e from BASF Canada Ltd) and Laminac* 4193 (ob-tainable from Cyanamid of Canada which are unsaturated polyester resins dissolved in styrene, there being incorporated in the resin about 1 part 2a of maleic anhydride for every 2 parts of styrene. Paraplex* P-444A
(obtainable from Rohm ~ Haas Company Canada Ltd.) is a similar suitable unsaturated polyester.
It is known to add material such as styrene to unsaturated ~ -polyester resins and in fact they are supplied by chemical suppliers diluted with sufficient styrene for eventual cross-linking of the polyester.
The proportions supplied are usually about 70 parts by weight polyester to 30 parts by weight styrene. The viscosity of such diluted resins is still far greater than 1000 cps. By the further dilution according to the present inventlon with monomers as aforementioned viscosities of perhaps 50 cps down to less than 1 cps are obtained. Such diluted polyesters * Trade Mark ,' ' ' , `
~09:2743 provide more monomer than is required for cross-linking of the polyester and when used according to the present invention polymerization of that monomer occurs as well as the cross-linking reaction. Obvlouoly when an unsaturated polyester resin is not used, the viscosity of the monomer components is negligible when compared to the use of preformed resin binders and cross-linking is not involved.
For the purposes of the present invention it has been fount possible to use proportions of unsaturated polyester resin dissolved in monomers so long as the viscosity of the solution in the monomers does not exceed about 50 cps. In terms of proportion by weight, the polyester resin can constitute up to about 50% by weight of the binder components, and is preferably 40% by weight or less.
As indicated previously the amount of binder component (a) which can be used according to the present invention is generally between 5 and 10% by weight of the composition, but even lower proportions are suitably down to about 3 %. The low viscosity of the liquid organic phase permits mixing in of high levels of aggregates, fillers and sand and other inorganlc components and the low surface tension of the liquid phase allows intimate contact between the organic particles. Because of the low proportions of liquid used, it is not so much the liquid phase that provides the characteristics of curing and of the final product but rather a product is provided which is a nearly inorganic, nearly mono-lithic structure with particles of sand and aggregate intimately adhering to each other. The final product has in fact more of the characteristics of granite or stone than plastic, or for that matter even hydraulic concrete.
The amount of binder can be increased somewhat above 10% but ~`
if increased too much then problems arise in obtaining a uniform concrete and the improved properties obtainable with the lower binder levels are sacrificed.
30 ` The polymerization initiators which are added according to the process of the present invention are free radical type initiators which will effect polymerization of the monomers, and where applicable, cross-linking of the polyester resins used. These initiators may be either those which are active at room temperature or at increased temperatures. An example for use at room temperature is benzoyl peroxide together with nitrogen containing promoters such as N,N-diethyl-m-toluidine and N,N-dimethyl-aniline. An example of an initiator for use at elevated temperature is bis-4-tertiary-butyl-cyclohexyl peroxydicarbonate. The use of heat activated initiators and heat during setting of the concrete i9 of ad-vantage in that it permits a longer pot-life of the fresh concrete mix.
Other examples of appropriate initiators will immediately occur to those skilled in the art. The proportions of initiator will generally be 0.1 to 5% by weight of other binder components.
As indicated previously standard concrete mixing and placing equipment may be used for the concrete according to the invention. For precast concrete components, the molds used are preferably closed molds although open molds are possible. The reason for this is partly because of volatility of the monomers when heat is used to effect setting and also -~
the use of closed molds prevents warping because heat can be applied from both sides and a more uniform polymerization obtained. If closed molds are used, it is not necessary that the ld be completely closed and by closed molds can be meant as well a mold with up to 10 - 30% of the concrete surface area being exposed.
It is standard practice in the manufacture of regular precast concrete to vibrate ~he concrete in order to place it and bring to the surface any air entrapped while mixing or pouring. The use of vibration in the process of the present invention is essential for those reasons and also for another, that is the achievement of minimum volume occupied by the aggregates or placement of the aggregates without voids. By reducing the viscosity of the liquid phase preferably to something of the order of less than 1 centipoise with concomitant reduction in surface tension the aggregates can settle freely on vibration and orient themselves in what inevitably turns out to be the most compact placement. This of .
10.
' ,~ ~.
109'~743 course cannot be achieved with viscous binders. Since this procedure allows solids to impinge on solids, the shrinkage normally a6soci~t4d with increasing monomer level and conversion to polymer is not experienced.
In the case of hydraulic concrete, over-vibration leads to segregation of the mix which is undesirable. In the present process over-vibration can be routinely used to ensure placing of the aggregates in the desired configuration.
Various vibrating devices can be used depending on the manner of manùfacture of the concrete. For example with molds for precast concrete table vibrators can be used whereas for cast-in-place applications internal vibrating devlces are appropriate. In fact any type of vibration may be used and any frequency, even mechanical shock, as long as it is intense. The energy requirements are not dependent on frequency and the amount of vibration that is to be used is determined empirically and is such as is sufficient to remove significant amounts of voids. In other words the spaces or gaps between aggregate particles are reduced to a minimum.
Once the concrete mixture has been cast and vibrated, the time required for setting will of course depend on the particular ini-tlator used and whether or not heat is applied. The time required may be anything from 5 minutes up to 3 hours or longer and the temperature may be from room temperature up to 200F or higher.
Reinforcing materials used in conventional concrete mixes may also be used according to the present invention. These may be for example reinforcing bars or steel mesh. Also steel fibres may be used in ~ -the present compositions and can be merely mixed in with the other com-ponents, which is unlike hydraulic concretes wherein the steel fibres on mixing tend to agglomerate. Such reinforcment improves the tensile strength and impact resistance of the concrete.
The polymer bonded concretes according to the present invention can be modified as to surface appearance for various architectural uses.
11.
~092743 The surface of the concrete can be treated or etched with any solvent for the polymer binder used so that an exposed aggregate effect i~ obtalnst.
A particularly useful solvent for polymethacrylate, polyacrylates or polystyrene is methylene chloride. Surface treatment of this type i8 normally produced in hydraulic concretes by etching with acids, retarding the surface cure of the concrete and/or by sand blasting.
A plastic-like finish on the concrete may be obtained in precast structures by applying a coating of pigmented resin in the mold prior to casting of the concrete. This surface coating adheres per- ~ -lQ manently to the concrete product. Examples of such resins are Palatal*
H-170 and Gel-Kote* (available from Glidden Company).
The following examples are intended to illustrate the present invention but are not to be limiting to the scope thereof.
In all the examples the aggregates used were added to a con-ventional pan-type mixer, the liquid ingredients except for initiator then added, followed by the other dry ingredients and finally the initiator.
Mixing was continued for two minutes and the mix then transferred to a closed 30 square foot mold. Vibration was carried out for two minutes using a 1~ horse power reciprocal vibrator operating at a frequency of 3450 rpm.
The conditions of curing or setting are detailed in each example.
Example 1 A polymer concrete according to the invention was prepared using the following components:
Polyester Resin 72% Styrene 28% (Palatal*H-170) 3.5%
Methyl Methacrylate 3.1%
Bis-4-Tertbutylcyclohexyl Peroxydicarbonate 0.08%
- Silica Flour ( >200 Mesh) 12.6%
Ottawa Silica (27 Mesh) 21.2%
Round Quartz Aggregates (1/8" - 3/8") 58.8%
Titanium Dioxide 0.8%
* Trade Mark 109~ 3 % Organic: 6.7 Heat Cure: (~ hour at 175F) Thickness of Casting: ~ 3/4"
Compressive Strength: 13,500 p.s.i. (ASTM C39-73), Flexural Strength: 2,750 p.s.i, (ASTM C78-75) Modulus of Elasticity: 6.6 X 106p.s.i.(ASTM C469-65) Example 2 The following components were used in preparation of a polymer concrete according to the invention:
Methyl Methacrylate 5.75%
Bis-4-Tertbutylcyclohexyl Peroxydicarbonate 0.05%
Titanium Dioxide 0.25%
Calcium Carbonate 250 Mesh + 12.00%
Calcium Carbonate 50 - 500 mesh 14.00%
Aggregates 1/8" - 1" 67.20%
% Organic: 5.8%
Heat Cure: (1 hour at 160F) Thic~ness of Casting: ~ 2" ' Example 3 The fo}lowing components were used:
Polyester resin 72%, Styrene 28% (Palatal*H-170) 3.20%
Butyl Acrylate 1.60%
, Methyl Methacrylate 1.60%
Silica Flour * (200 Mesh) 12.00%
Ottawa Silica (27 Mesh) 32.00%
Round Quartz Aggregates (1/8" - 3/4") 49.00%
Titanium Dioxide 0.13%
N-N-Diethyl-m-Toluidine 0.04%
N,N-Dimethylaniline 0.08%
Benzoyl Peroxide 70% (Granules) 0.25X
-: ~
~0!9Z743 % Organic: 6.77 Room Temperature Cure: (3 hours at 70F) Thickness of Casting: ~ 2"
* 7.8% retained on 200 mesh; 12.9% retained on 270 mesh;
11.1% retained on 325 mesh, pan: 66.7%.
Example 4 -This concrete was prepared from the following:
Polyester Resin 72%, Styrene 28%(Palatal*H-170) 2.5%
la Methyl Methacrylate 2.5%
Bis-4-Tertbutylcyclohexyl Peroxydicarbonate 0.1%
Silica Flour ( > 200 Mesh) 12.9%
Ottawa Flour (27 Mesh) 21.9%
Round Quartz Aggregates (1/8" - 3/4") 59.7%
Titanium Dioxide 0.4%
% Organic: 5.1 Heat Cure: (3/4 hour at 175 F) Thickness of Casting: ~ 2"
Thls example was also repeatèd using only styrene in place r 20 of methyl methacrylate with comparable results.
' Example 5 The following were used to prepare a concrete mix:
Polyester resin 72% Styrene 28%(Palatal* H-170) 3.3%
Methyl Methacrylate 2.7%
` Bis-4-Tertbutylcyclohexyl Peroxydicarbonate 0.6%
Silica Flour ( ~200 Mesh) 10.0%
Ottawa Silica (27 Mesh) 15.0%
Round Quartz Aggregates (1/8" - 3/8") 68.5%
Iron Oxide Color 0.5%
14.
.. .. . . . . . .
., ~ - . . - . :
~09~43 % Organic: 6.1 Heat Cure: 15 Minutes at 200 F
Thickness of Casting:
Example 6 The following ingredients were mixed and cured:
Polyester resin 72%, Styrene 28% (Palatal*H-170) 2.9%
Methyl Methacrylate 2.9%
Bis-4-Tertbutylcyclohexyl Peroxydicarbonate 0.06%
Silica Flour ( >200 Mesh) 3.8%
Aluminum Hydrate (Average 100 Mesh) 10.0%
Ottawa Silica (27 Mesh) 16.2%
Round Quartz Aggregates (1/8" - 1/2") 64.0%
Titanium Dioxide 0.2%
% Organic: 5.9 Heat Cure: 1 Hour at 165F
Thickness of Casting: 2"
Example 7 A concrete was prepared from the following:
Polyester Resin 72% Styrene 28% (Palatal*H-170) 3.3%
Methyl Methacrylate 3.3%
Bis~4~Tertbutylcyclohexyl Peroxydicarbonate 0.1%
Silica Flour ( ~200 Mesh) 6.0%
Aluminum Hydrate (Average 100 Mesh) 13.4%
Ottawa Silica (27 Mesh) 15.2%
- Round Quartz Aggregates (1/8" - 1/2") 57.46%
Titanium Dioxide 0.14%
Molybdate Orange 1.12%
; "~
% Organic: 6.7 Heat Cure: ~ Hour at 175F
Thickness of Casting: < 2"
The polymer concretes of Examples 2 - 7 had properties very similar to those of the concrete of Example l,for instance compressive strengths of the order of 13,500 psi.
It was found that the properties of the concretes of the foregoing Examples did not vary to any significant degree for the binder proportions specified.
As an indicationof the fire resistant properties of polymer concretes as illustrated in Examples 6 and 7, a concrete made from the components as listed in Example 7 but without the molybdate orange coloring was found not to give off smoke or flame during decomposition by a 2500F heat source. Smoke emission according to ASTM D2843 was 1% while ~ --a test for fire resistance (ASTM D2863) resulted in an oxygen lndex of over 80.
All of the foregoing examples of polymer bonded concretes accorting to the invention may be used for precast panels for-fascia panels for buildings having thicknesses of 3/8 to 4'i, patio slabs~ concrete flower boxes, garden furniture, load bearing or non-load bearing sandwich panels using urethane foam sandwich between two -slabs of polymer concrete ;~` adhered both mechanically and chemically, wall cladding 3~8 to 1 inch thick to replace conventional lath and stucco systems, plywood and aluminum and steel siding, and the like.
- The polymer bonded concretes of examples 1, 3, 4 and 5 are particularly suitable for the manufacture of drain, sewer and other pipes because of chemical and abrasion resistance. These polymer concretes -are also of use for chemically resistant articles such as pump motor boxes, storage tanks and basis, floor slabs and tiles.
- 16.
`- 109~7~3 The polymer concrete of Example 1 has been used in the form of panels to protect the sides, undersides, or supporting plll~rs of elevated highways because of its extremely high chemical resistance.
This concrete has also been used as permanent, white, impervious forms for highway median strips, these forms being thin shells utilizlng regular hydraulic concrete as filler.
The polymer concrete of example 4 is abrasion resistant and is particularly suitable for the manufacture of railroad ties and tracks for rubber tired subway cars.
la The polymer concretes of examples 6 and 7 are particularly suitable for the manufacture of fire resistant panels and the like because of the low binder content and inclusion of aluminum hydrate.
`
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the preparation of a polymer bonded concrete containing from 3 to less than 10% of organic binder material which process comprises (1) mixing an aggregate consisting of sand, stone or gravel or mixtures thereof with binder components comprising (a) an unsaturated polyester resin dissolved in styrene monomer, the solution being of low viscosity and containing additional monomer in excess of that required for crosslinking of the polyester, said additional monomer being selected from the group styrene, methyl methacrylate and butylacrylate, and (b) a free radical polymerization initiator, to form a mixture of said aggregate and said binder components;
(2) casting said mixture;
(3) subjecting said mixture to intense vibration to pack solids therein to occupy the minimum possible volume and sub-stantially eliminate voids; and (4) causing said monomers to polymerize by the application of heat to produce said polymer bonded concrete.
(2) casting said mixture;
(3) subjecting said mixture to intense vibration to pack solids therein to occupy the minimum possible volume and sub-stantially eliminate voids; and (4) causing said monomers to polymerize by the application of heat to produce said polymer bonded concrete.
2. The process of claim 1 wherein heating is applied in the range of temperature up to 200°F.
3. The process of claim 1 wherein fillers are also mixed with said aggregate and binder components.
4. The process of claim 1, 2 or 3 wherein a solution of polyester in monomer is used having a polyester content of not greater than 50% by weight of binder.
5. The process of claim 1, 2 or 3 wherein a solution of polyester in monomer is used having a polyester content of 40% or less based on binder.
6. The process of claim 1, 2 or 3 wherein the initiator is bis-4-tert--butylcyclohexyl peroxydicarbonate.
7. The process of claim 1, 2 or 3 wherein binder component (a) comprises about 5 to less than 10% of the total composition.
8. The process of claim 1 wherein the initiator is used in an amount of about 0.1 to 5% by weight of other binder components.
9. The process of claim 1 wherein a fire-retardant material is incorporated in an amount of 20-200% based on binder.
10. The process of claim 9 wherein the fire-retardant material is selected from the group of alumina trihydrate or zinc borate.
11. The process of claim 1, 2 or 3 wherein the mixture is cast in a closed mold which covers 70% or more of the surface of the mixture.
Priority Applications (10)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA304,687A CA1092743A (en) | 1978-06-02 | 1978-06-02 | Polymer concrete having low binder levels |
| CA353,198A CA1113700A (en) | 1978-06-02 | 1980-06-02 | Polymer concrete having low binder levels |
| IL61397A IL61397A (en) | 1978-06-02 | 1980-11-03 | Polymer concrete having low binder levels |
| EP80304109A EP0052166B1 (en) | 1978-06-02 | 1980-11-14 | Process for the preparation of polymer bonded concretes |
| AT80304109T ATE18192T1 (en) | 1978-06-02 | 1980-11-14 | PROCESS FOR THE PRODUCTION OF POLYMER BOND CONCRETE. |
| DE8080304109T DE3071455D1 (en) | 1978-06-02 | 1980-11-14 | Process for the preparation of polymer bonded concretes |
| ZA00806782A ZA806782B (en) | 1978-06-02 | 1980-11-23 | Polymer concrete having low binder levels |
| MX185216A MX154143A (en) | 1978-06-02 | 1980-12-15 | PROCEDURE FOR THE PREPARATION OF A CONCRETE LINKED BY POLYMER |
| BR8008230A BR8008230A (en) | 1978-06-02 | 1980-12-16 | PROCESS FOR THE PREPARATION OF POLYMER CONNECTED CONCRETE |
| US06/217,498 US4346050A (en) | 1978-06-02 | 1980-12-17 | Polymer concrete having low binder levels |
Applications Claiming Priority (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA304,687A CA1092743A (en) | 1978-06-02 | 1978-06-02 | Polymer concrete having low binder levels |
| US91819678A | 1978-06-22 | 1978-06-22 | |
| US4414179A | 1979-05-31 | 1979-05-31 | |
| US11925980A | 1980-02-07 | 1980-02-07 | |
| IL61397A IL61397A (en) | 1978-06-02 | 1980-11-03 | Polymer concrete having low binder levels |
| EP80304109A EP0052166B1 (en) | 1978-06-02 | 1980-11-14 | Process for the preparation of polymer bonded concretes |
| ZA00806782A ZA806782B (en) | 1978-06-02 | 1980-11-23 | Polymer concrete having low binder levels |
| MX185216A MX154143A (en) | 1978-06-02 | 1980-12-15 | PROCEDURE FOR THE PREPARATION OF A CONCRETE LINKED BY POLYMER |
| BR8008230A BR8008230A (en) | 1978-06-02 | 1980-12-16 | PROCESS FOR THE PREPARATION OF POLYMER CONNECTED CONCRETE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1092743A true CA1092743A (en) | 1980-12-30 |
Family
ID=27575705
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA304,687A Expired CA1092743A (en) | 1978-06-02 | 1978-06-02 | Polymer concrete having low binder levels |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1092743A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1987000828A1 (en) * | 1985-08-08 | 1987-02-12 | Aktieselskabet Aalborg Portland-Cement-Fabrik | A shaped article and a method for producing the article |
| US5800752A (en) * | 1996-01-11 | 1998-09-01 | Charlebois Technologies Inc. | Process for manufacture of polymer composite products |
-
1978
- 1978-06-02 CA CA304,687A patent/CA1092743A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1987000828A1 (en) * | 1985-08-08 | 1987-02-12 | Aktieselskabet Aalborg Portland-Cement-Fabrik | A shaped article and a method for producing the article |
| US5800752A (en) * | 1996-01-11 | 1998-09-01 | Charlebois Technologies Inc. | Process for manufacture of polymer composite products |
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