Effects of milling Al(OH)3 prior to mix with Ca(OH)2 for a rapid cement hardener

Positive effects of milling Al(OH)3 prior to mix with Ca(OH)2 are elucidated to develop a rapid hardener for portland cement. With the hardener thus obtained, compressive strength of portland cement exceeds 5 MPa within 2 h. Rapid formation of calcium aluminate hydrate (CAH) in cement paste is found to be a key issue. Milling a mixture of Al(OH)3 and Ca(OH)2 in contrast, results in an in situ formation of CAH to decrease considerably the effect of rapid hardening.