Properties of shrinkage-reducing admixture-modified pastes and mortar

摘要

La propriété récherché inclure: résistance-électrique, hydratation taux, liberté-contraction et contraction craquée, il se trouve que contraction-réduction admixtion (CRA) peut réduir la liberté-contraction et différer l'existence de contraction craquée, la CRA peut avoir â l'influence sur la retard de hydratation processus dans la contraction de sécheresse. Toutefois, dans la coudition de semi-adiabatisme, la CRA peut see contraction; durcissement taux nblement avoir l'accélération de hydratation processus.%A comprehensive study on the influence of a shrinkage-reducing admixture (SRA) on properties of ordinary Portland cement and shrinkage-compensating cement has been conducted. The properties investigated include: electrical resistivity, hydration heat rate, free shrinkage and restrained shrinkage cracking. It is found that the shrinkage-reducing admixture (SRA) can reduce the free shrinkage and postpone the occurrence of shrinkage crack significantly. The SRA has also an effect to retard the hydration process of Portland cement under normal condition. However, under semi adiabatic condition, it seems that SRA accelerates the hydration process. A new concept of the hardening ratio, ρ_H, is proposed in the study. It is indicated that the hardening ratio, ρ_H, and compressive strength development have very good linear relationship.