Decision-making on Increasing Limestone Content of General Purpose Cement

Following the publication of the Australian Standard AS 3972, “General purpose and blended (GP) cements” in 2010, a research programme was undertaken to determine the effect, if any, of increasing the maximum permissible mineral addition in Type GP cement. This paper involves the assessment of the variation in standard laboratory concrete properties due to increasing the limestone addition in cement. Workability, bleed water, compressive strength and drying shrinkage of concrete samples with different limestone contents in the range of 5% to 12% were examined. Based on the research results, it is recommended that the maximum allowable mineral addition in Type GP cement be increased from 7.5% to 12%.