In the past few decades significant efforts have been made to reduce the CO2 emissions associated with the manufacture of portland cement mainly by making the process more energy efficient and increasing the use of alternative fuels. Further reductions in CO2 can be achieved by lowering the clinker component of the cement as the pyroprocessing used to manufacture clinker produces approximately 1 tonne of CO2 for every tonne of clinker. Traditionally reductions in the clinker content of cement have been achieved by producing blended cement consisting of portland cement combined with a supplementary cementing material (SCM). In Canada, it is now permitted to intergrind up to 15% limestone with cement clinker to produce Portland limestone cement or blended Portland limestone cement. Recent trials were conducted at the Brookfield cement plant in Nova Scotia to evaluate the performance of a blended cement containing 15% ground granulated blastfurnace slag (an SCM) with that of a blended Portland limestone cement containing the same amount of slag plus 12% interground limestone. The performance was evaluated by constructing a section of concrete pavement using a number of concrete mixes produced with the two cements plus various amounts of fly ash (another SCM) added at the ready-mixed concrete plant. A wide range of laboratory tests were performed on specimens cast on site during placing of the pavement. The results of these tests indicate that cements were of equivalent performance.
