Resilient Response and Permanent Strain of Steel Slag-Fly Ash-Dolime Mix

There is a growing need to use the waste materials in the construction of transportation routes because of lack of good quality aggregates on one hand and concerns regarding disposal of huge quantity of waste materials on the other. In this study, engineering properties of steel slag-fly ash-dolime (SFD) mixes were investigated for their effective utilization as base course material in flexible pavements. The effects of fly ash and dolime percentages and the curing age on the resilient modulus and permanent strain of SFD mixes were investigated. The performance of various stress-dependent models for the prediction of resilient modulus was compared, and the model constants of SFD mixes for a three parameter model were presented. A mix of 75% steel slag, 25% fly ash, and 15% dolime was obtained as the optimum mix. The optimum SFD mix with a 28 day curing period exhibited 60% higher resilient modulus and 83% lower permanent strain than the conventional Wet Mix Macadam (WMM). Volumetric swelling of the optimum mix was found to be within the acceptable limits. Observed test results were explained through a microlevel study using X-ray diffraction (XRD) and scanning electron microscope (SEM) tests. Finite element analyses were performed for a flexible pavement system with five layers, and the service life of the pavement with SFD mix as the base material was found to be approximately fifty percent higher compared to that of the pavement with WMM base layer.