GB885333A - A process for treating masonry - Google Patents

Abstract

Masonry surfaces are treated by applying thereto a solution or emulsion containing from 0,01% to 1% by weight of an air-drying organosilicon compound which is allowed to dry, and applying a Portland cement composition to the treated surface and allowing it to set. The organosilicon compound is a hydrolyzable silane, a partial hydrolysate thereof, an organopolysiloxane, or an alkali metal salts of these. In the organosiloxanes a major portion of the polymer linkages are Si-O-Si linkages and any remaining linkages are of the type Si-Sc or Si-R1-Si, R1 being a divalent hydrocarbon radical, or both. The remaining valencies of the silicon atoms are satisfied by monovalent hydrocarbon radicals, which may be alkyl, alkenyl, cycloaliphatic, cyclo-alkenyl, aryl, aralkyl or alkaryl. The organosilicon compound may be applied as a solution, e.g. in xylene, toluene, mineral spirits or chlorinated hydrocarbons, or as emulsion, and the alkali metal salts as aqueous solutions. Suitable Portland cement compositions contain at least 48% by weight (dry basis) of Portland cement, and may also contain lime, pigments, (which may be coated with hydrolyzable silanes), binders such as sodium silicate, inert fillers, wetting agents and materials such as bentonite, calcium stearate, aluminium silicate and calcium chloride, and a portion of the primer dispersion. They may be applied as a grant, a poured concrete, a stucco or a paint to such masonry as mortar, concrete, cement-base paint coatings, asbestos-cement, sandstone, limestone, brick, cinder block, "Brickcrete" (Registered Trade Mark), and tile, after these have been coated with the organo-silicon compound. Examples show the bond strength of a Portland cement mix, of 3 parts masons sand to 1 part Portland cement, to bricks and other materials pretreated with various organosilicon compounds. Specifications 714,461, 749,799, 749,938 and 860,522 are referred to.ALSO:In providing masonry surfaces with a portland cement coating, (see Group III), the surfaces are pretreated with a solution or emulsion of an air-drying organosilicon compoind. The examples include (2) a xylene solution of a mixture of 85% by weight of (A) a liquid alkoxylated organosilicon compound and 15% by weight of (B) a non-alkoxylated polysiloxane resin: (A) has an average of about 1,1 total monovalent hydrocarbon radicals per silicon atom and 24% by weight of silicon-bonded methoxy groups and (B) was a copolymer of SiO2 and Me3SiO0,5 units with about 1,2 methyl groups per silicon atom: (4) a mixture of (i) 75% by weight of a copolymer of 75 mol % of monomethyl-siloxane, units, 24 mol % of dimethyl-siloxane units and 1 mol % of trimethyl-siloxane units and containing 8% by weight of silicon-bonded methoxy groups and (ii) 25% by weight of a monopropylsiloxane containing 18,4% by weight of siliconbonded ethoxy groups. Alkali metal siloxanolates may be used in aqueous solution. Specifications 714,461, 749,799, 749,938 and 860,522 are referred to.