The effect of ground limestone on the properties of Portland and slag-Portland mixed cement

The properties were studied of Portland and slag mixed cements containing admixtures of 5 to 30 wt.% of ground limestone (as replacement of cement) with a specific surface area of 400 to 900 m(2) kg(-1). The decrease in strength in terms of increasing limestone content indicates that the limestone does not take part in cement gel formation. However, it is theoretically possible to prepare, from slag cement SPC 325 and 10-12 wt.% ground limestone with a specific surface area of 550 m(2) kg(-1), a mixed cement exhibiting higher 2-day and 7-day strengths, and a 28-day strength reduced by max. 10% (compared to the original SPC 325 cement).