Aminoalkyl phosphonic acid or salt concrete fluidisers - used in combination with pore-formers to give improved frost resistance without strength loss

摘要

Fluidising agents which can be used in combination with pore formers (esp. those based on abietic acid) in mortars and concrete are aminoalkylphosphonic acids of formula (I) or (II) or their alkali(ne earth)-ammonium or amine-salts. In formulae, X = H or COOH; R = 1-3C alkyl; and n = 1-6. The amt. of (I) or (II) used is pref. 0.01-0.5% dry wt. based on cement content of the compsn. Typical fluidising agents are (1) N,N-di-Me-aminomethane-diphosphonic acid; (2) N,N-bis(methylphosphonyl) methylamine; (3) N,N-bis(methylphenyl)-epsilon-aminocaproic acid; or (4) Na salts of (1)-(3). ADVANTAGE - Mortars or concrete contg. the combination are workable for up to 90 mins. and the presence of (I) or (II) improves the frost resistance without there being any strength loss.