OPTIMAL CRITERIA OF ALGERIAN BLENDED CEMENT USING LIMESTONE FINES

The effect of substitution of Portland cement by limestone up to 40% as well as its fineness on the physico-mechanical properties of fresh and hardened cement pastes is studied. The binder was prepared by substitution of cement by limestone filler. Fillers were chosen of various particle sizes and with percentages from 5 to 40. Test results revealed that the replacement of Portland cement by the finest filler of limestone slightly decreases the consistency and the setting times (initial and final). The total porosity decreases and accordingly the compressive strength is improved with the content and fines of limestone. Although limestone has a little accelerating effect oil the hydration process of Portland cement, but acts only as a filler reducing the porosity due to its compact structure, in which the compressive strength of the hardened cement paste is enhanced. The XRD and DTA analyses of samples cured up to 28 days showed that this amelioration is due to formation of new hydrated compounds. It is concluded that an addition of finely ground limestone filler only up to 15% gives a better strength.