Experimental Investigation on Use of Coarse EAF Slag Aggregate and GGBFS in Roller Compacted Concrete Pavement

Abstract

The present study investigates the effect of partial and full replacement of natural coarse aggregate with coarse electric arc furnace (EAF) slag aggregate and partial replacement of cement with ground granulated blast furnace slag (GGBFS) on the mechanical and durability properties of roller compacted concrete pavement (RCCP).The replacement level of EAF slag aggregate were at five levels (i.e. 0% ,25% ,50%,75% & 100%) and of GGBFS was (0 % ,30 %,50% & 70%).The EAF slag aggregate were stabilized by exposing to outdoor condition for several years and the volumetric expansion test using steam exposure device was done to check volume stability. Soil compaction method was used for mix proportioning of RCCP. The fresh properties of RCCP investigated were fresh density and modified vebe test was done to measure the consistency of concrete. For investigating the mechanical properties various test were done at 7 and 28 days (i.e. Compressive strength, split tensile strength, flexure strength modulus of elasticity) and also non-destructive testing was done at 28 days (i.e. Ultra pulse velocity test (UPV) & rebound hammer test).The durability test done at 28 days were water absorption, skid resistance, abrasion resistance, carbonation & hot water curing. The results showed that with the increase in slag aggregate percentage there was increase in the fresh density of concrete and also slight increase in the vebe time but with the increase in GGBFS percentage the vebe time decreased and the fresh density increased upto 30 % GGBFS replacement. The mechanical strength properties improved with the increase in slag aggregate percentage but with the increase in GGBFS percentage it decreased when compared to 100 % cement mixes. In UPV test and rebound hammer test all the mixes showed excellent quality of concrete except mixtures containing 70 % GGBFS. In durability water absorption, skid resistance and abrasion resistance increased with increase in slag aggregate percentage whereas with GGBFS mixes these properties decreased. The carbonation and hot water curing had negligible effect on RCCP containing EAF slag aggregate. Till 50 % GGBFS replacement & 100 % EAF slag aggregate replacement all the results of mechanical properties and durability properties were comparable to control mix.