Rapid hardening of cement by the addition of a mechanically activated Al(OH)3-Ca(OH)2 mixture

Abstract

Rapid hardening of cement was achieved in the present study by adding a mechanically activated Al(OH)3-Ca(OH)2 mixture to the starting cement paste. Among the dominant parameters for hardening were the mechanical treatment time for the Al(OH)3 powder and the Al(OH)3/Ca(OH)2 ratio. The hardening mechanisms are discussed here in terms of the ionic concentration of the solution and the hydration products created when the Al(OH)3-Ca(OH)2 mixture was added to water. Mechanical activation of the Al(OH)3 powder accelerated dissolution into an aqueous alkaline solution and induced the formation of calcium aluminate hydration products. Those hydration products increased the compressive strength of the cement paste at a very early stage of hardening.