INFLUENCE OF FINELY GROUND LIMESTONE POWDER ON FLEXURE STRENGTH OF MORTAR AND BLENDED CEMENT PROPERTIES

The effects of replacement of Portland cement by ground limestone as well as its specific surface Blaine (SSB) on flexure strength of mortar and cement properties were studied. The binder was composed of cement and limestone, which was prepared by eight replacement levels of limestone powder (0, 5, 10, 15, 20, 25, 30 and 35) of binder by mass and four levels of specific surface (300, 600, 800 and 1000m(2)/kg. Test results demonstrated that the water requirement of normal consistency and the setting times decreased as the replacement level increased and the extent of reduction was noticeable with the increase of SSB of limestone powder. The flexure strength of mortar incorporating blended limestone powder cement increased steadily with ages. The flexure strength decreased with the increase of replacement level of limestone, while it increased with an increase of SSB at the same replacement level and age. The SSB influence factor was created to describe the effect of SSB of limestone powder on the flexure strength and the strength activity index of limestone powder concerning the replacement levels, specific surface of limestone powder and specimens ages was established. The grade of limestone powder was suggested in order to reasonable utilization.