Cement admixture which inhibits drying shrinkage

摘要

A cement admixture consists of (A) an oxyalkylene ether adduct of formula RO(AO)mH, where R = 1-7C alkyl or a 5-6C cycloalkyl group, A = 2-4C alkylene group, O = oxygen atom and m = 1-10; and at least one betaine, in which (B) is present in amounts 0.01-2.0 wt.% of (A). Also claimed are: (1) a method of inhibiting dry shrinkage in cement compositions whilst being able to provide air void content to formations formed from the composition comprising introducing 0.1-5 wt.% of an admixture into a cement composition; and (2) a cement composition containing 0.15 wt.% of the above admixture.