Latex emulsion concrete

Latex emulsions have improved the qualities of nonplastic concrete. The slow growth of this advance in construction may be attributable to the lack of dialogue between the civil and plastic engineer. However, there are already enough case histories available to convince the civil engineer of the advantages of this improved hydraulic cement. 

While PC, latex emulsion concrete, and caulking compositions represent only a small percentage of the entire plastics business, they are one of the most important to the construction industry. The American construction industry has been dependent on plastic sealants and caulking compositions but has been slow to accept plastic concrete. Fortunately, the latter has been successfully used for many years in other countries and it is now being accepted in the U.S. 

A relatively inexpensive bonding agent that may be used to ensure a positive bond of a new concrete overlay is a latex-reinforced cement slurry grout. Portland cement and sand (in a ratio of 1 3 by volume) are combined with a gauging liquid that is a mixture of equal volumes of water and an acrylic or polyvinyl acetate latex emulsion, as described in the table. This emulsion must be nonre-emulsifiable. The gauging hquid, based on the latex blend, is added to the cement-sand powder until a creamy paste is developed. This paste is scrubbed into the surface of the base slab, covering the surface thoroughly. New concrete is then placed on this bond hue, which is approximately M6-in thick. 

Latex-modified concrete is conventional Portland cement concrete with the addition of a polymeric latex emulsion. The water of suspension in the emulsion hydrates the cement and the polymer provides supplementary binding properties to produce a concrete with a low water-cement ratio, good durability, good bonding characteristics and a high degree of resistance to penetration by chloride ions, all of which are desirable properties in a concrete overlay. 

Chem. Descrip. Potassium-naphthalene-sulfonate polycondensate Uses Dispersing agent for latex, emulsion polymerization, and concrete Properties 50% liq. 

Poly(vinyl acetate) and its copolymers with ethylene are available as spray-dried emulsion soHds with average particle sizes of 2—20 p.m the product can be reconstituted to an emulsion by addition of water or it can be added directly to formulations, eg, concrete. The powders may be used to raise soHds of a lower soHds latex. Solutions of resin in methyl and ethyl alcohol at 2—50 wt % soHds are also available. 

In contrast to other polymers the resistance to water permeation is low due to the hydrolysis of the poly(vinyl acetate) (163,164). Ethylene copolymers have been developed which have improved water resistance and waterproofness. The polymer can be used in the latex form or in a spray-dried form which can be preblended in with the cement (qv) in the proper proportion. The compressive and tensile strength of concrete is improved by addition of PVAc emulsions to the water before mixing. A polymer-soHds-to-total-soHds ratio of ca 10 90 is best. The emulsions also aid adhesion between new and old concrete when patching or resurfacing. 

Admixtures are sometimes used to reduce permeabiUty of concrete (80—82). These iaclude pore-filling materials such as chalk. Fuller s earth, or talc water repellents such as mineral oil, asphalt, or wax emulsions organic polymers (acryflc latexes, epoxies) and salts of fatty acids, especially stearates. 

A bond coat of a polymer latex (also called polymer emulsions or dispersions) such as styrene butadiene (SBR), polyvinyl acetate (PVA) acrylics or modified acrylics. These are applied to the prepared concrete as... 

Of the several types of the polymer-modified mortars and concretes used for various construction applications, latex-modified mortar and concrete are by far the most widely used materials. Latex-modified mortar and concrete are prepared by mixing a latex, either in a dispersed liquid or as a redispersible powder form with fresh cement mortar and concrete mixtures. The polymers are usually added to the mixing water just as other chemical admixtures, at a dosage of 5-20% by weight of cement. Polymer latexes are stable dispersions of very small (0.05-5 pm in diameter) polymer particles in water and are produced by emulsion polymerization. Natural rubber latex and epoxy latex are exceptions in that the former is tapped from rubber trees and the latter is produced by emulsifying an epoxy resin in water by the use of surfactants [87]. 

Polectron 430. [ISP] Sfyrene/PVP co-pdymer binder and adhesive f< -wood, cotton, p , glass, flour, concrete sta-bflizer and opadfien laundry processing stabilizer for detergents textile and paper coatings, latex nig backups, floor wax emulsions, and cosmetics. 

Surfonic . [Texaco] Ethoxylates emulsifier, wetting agent dry cleaning detergent penetrant solubilizer, lime soap dispersant antifoamer used in agric., cosmetics, industrial cleaners, ceramics, concrete, film developing, emulsion polymerization, latexes. 

This PVA latex leaves a dried film which is flexible without the addition of a plasticizer. The film has excellent water resistance, light stability, good aging characteristics and good film consolidation. This particular PVA latex may be used as a film forming binder in a water-based emulsion paint. Its particular characteristics of compatibility with cement have led to wide uses of this latex as an adhesive and an admixture for cementitious mortars and concrete. 

Table 3J, Formulations for Emulsion Polymerization of Typical Polymer Latexes as Cement Modifiers. ( 1991, American Concrete Institute, Sprinted widi pemussion.)...

Table 5.1 Rec for Emulsion Polymerization of Typical EVA Latex for Redi rsible EVA Powder. ( 1990, American Concrete Institute, reprinted wiA permission.)...

Chem. Descrip. Complexed lecithin CAS 8002-43-5 EINECS/ELINCS 232-307-2 Uses Instantizer, spray oils, mold release for foods food emulsifier for w/ 0 emulsions concrete (powder dispersant) dust control latex paints coatings/adhesives feed additives leather tanning lubricants mold release agents pesticides/herbicides corrosion/rust inhibitors putty/ caulking compds. emulsifier for w/o emulsions Properties Translucent fluid vise. 10 stokes HLB 2.0 acid no. 25 max. Beakin LV3P [ADM Lecithin]... 

Chem. Descrip. Fully hydrolyzed PVAL, 99-99.8% hydrolysis CAS 9002-89-5 EINECS/ELINCS 209-183-3 Uses Film-former, binder in adhesives, paper, paperboard sizing and coatings, textiles, films, building prods. strength additive for concrete, cement binder for pigments, ceramics, cements, plastics, particleboard oil/solv. barrier props, in hoses, gaskets, pipes carrier for optical bright-eners cosmetic and personal care incl. face masks emulsifier in emulsions and latexes... 

Chem. Descrip. Vinyl acetate copolymer emulsion Uses Film-former in primers, sealers, specialty coatings, latex paints (exterior masonry and wood), roof coatings, concrete admixtures Features Fligh m.w., permanently flexible emulsion, flow, holdout, and machining properties produces films that are clear, transparent, and odorless... 

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