Effect of ground granulated blast furnace slag (GGBFS) on RCCP durability

Having recorded a profile of success in mass concrete applications such as in dam building, roller compacted concrete has recently stimulated a growing interest in road pavement construction as a novel application. The present study was designed to investigate the effects of ground granulated blast furnace slag (GGBFS) used in concrete mixtures on durability properties of roller compacted concrete pavements as water absorption, permeability and freeze-thaw cycles. For this purpose, eight principal concrete mixes were designed containing four blast furnace slag levels (0, 20, 40, and 60% relative to the weight of the cementitious materials) and two cementitious material levels (12 and 15% relative to the aggregate weight) at an optimum moisture content. Results showed that the moisture content required for the concrete to reach its maximum compaction increased with increasing slag content. Moreover, cracking and porosity declined with increasing slag content up to a certain level beyond which both took a rising trend. This was evidenced by the minimum and maximum levels of concrete cracks and porosity for slag contents of 40% and 60%, respectively, compared to the levels observed in plain concrete lacking GGBFS. Concrete permeability was also observed to decline with the experimental concrete mix designs containing 20 and 40% GGBFS but increased for a GGBFS content of 60%. Finally, increasing cementitious materials from 12 to 15% was observed to reduce concrete permeability. The highest destructive effect due to 150 and 300 freeze-thaw cycles was observed with mix designs having a GGBFS content of 40%; however, mix designs containing a GGBFS of 60% exhibited relatively improved resistance against the effects of freeze-thaw cycles.