GB937216A - Cold setting cement compositions - Google Patents

Abstract

A cold setting cement composition comprises a particulate filler contributing the major proportion of the solids content of the cement, an aqueous silica sol as a binder for the filler, from 0,2% to 15% by weight based on the weight of filler of a solid alkali metal silicate as a setting agent for the silica sol, the silicate having an alkali metal oxide to silica mole ratio within the range from 1 : 1 to 1 : 4,2, and 0,25% to 1,0% based on the combined weight of filler and setting agent of a polyvinyl alcohol obtained by hydrolysing polyvinyl acetate, preferably to an extent of 75% to 100%. The particulate filler (e.g. silica, silicates, various metal oxides) is one which is insoluble in water and substantially inert to the silica sol binder. The silica sol is one which is normally precipitated as a gel by alkalis or salts, and is used in an amount sufficient to bond the filler into a coherent mass. The polyvinyl alcohol, a 4% aqueous solution of which has a viscosity between about 4 and 60 centipoises at 20 DEG C., is added in solid form, and is preferably blended with either the filler or silicate setting agent, or a mixture of the two. The preferred filler material is a combination of silica sand and quartz flour, the ratio of powder to liquid in compositions containing this filler being preferably from 3, : 1 to 3,7 : 1. In examples, the filler employed is a mixture of quartz, sand and clay; the silica sol binder contains 30% SiO2 and less than 1% Na2O; the setting agent has the composition Na2O 3,2 SiO2. Other fillers specified are beryl, mullite, fluospar and silicon carbide. Specification 816,233 is referred to.