Effects of ground granulated blast furnace slag in Portland cement concrete : expanded study

Abstract

This research examined the properties of concrete containing grade 120 slag cement at replacement levels of 0%, 30%, and 50%. The primary concrete properties studied were compressive strength, split-tensile strength, and deicer scaling resistance. Material variations included four sources of ordinary portland cement and two types of coarse aggregate. Strength properties were studied at room temperature and 40?F mix and curing conditions. Deicer scaling resistance was studied for concrete cured under six curing conditions. Carbonation of concrete cured under these six conditions was also investigated. It was determined that concrete containing 30% and 50% replacement of ordinary portland cement (OPC) with grade 120 slag cement had a decreased initial compressive and tensile strength compared to OPC concrete. However, by 14 days, the grade 120 slag cement concrete strength equaled or surpassed that of OPC concrete. Compared to OPC concrete, the time to reach 3000 psi traffic opening strength was delayed by 1 to 2 days for 30% replacement and by 3 to 4 days for 50% replacement. Deicer scaling resistance decreased as the level of slag cement replacement increased. Curing methods which limited carbonation produced concrete with the highest level of scaling resistance. Air-cured concrete had higher scaling resistance than concrete cured with commercial curing compounds. The scaling resistance of all grade 120 slag cement concrete was within acceptable limits. Variations in portland cement source caused changes in strength and scaling resistance properties. Variation in coarse aggregate influenced compressive and tensile strengths but did not influence the deicer scaling resistance. Comparisons with previous research on grade 100 slag are included.