Effect of limestone content on properties of portland limestone cement produced by intergrinding

Abstract

Limestone is used very commonly as a mineral admixture in the production of blended Portland cement because of its availability and low cost. Since using limestone reduces the amount of clinker used, it helps to reduce CO₂ emission from the cement production process. Limestone is added into cement commonly by intergrinding with clinker, gypsum and other admixtures (if any). International studies show that the influence of limestone depends not only on the content and fineness of limestone but also on the mineral composition of the clinker used. The objective of this study was to evaluate the influence of limestone content on some properties of Portland limestone cement produced by intergrinding method using materials available in Vietnam. The limestone contents used were 0, 10, 20, and 30%. The properties of the cement investigated include particle size distribution, water of consistency, setting time and compressive strength at ages of 1, 3, 7 and 28 days. The results show that, when increasing the limestone content, the cement particle size was distributed more widely, the water of consistency increased by 1%, and the initial and final setting time decreased slightly. The compressive strength also tended to decrease, the level of decrease was highest at the age of 1 day, gradually decreasing in the later ages. Based on the degree of strength decrease at ages of 3 and 28 days, the limestone content used should not be more than 20%.