Effect of Blending Steel Slag Aggregates on the Polishing Resistance of Asphalt Pavement Surface

The objective of the work presented in this paper is to investigate the effect of blending steel slag aggregates (SSAs) with natural aggregates (NAs) on the polishing resistance of the asphalt pavement surface. The investigation involved polishing five sources of NA (granite [3] and amphibolite [2]), one source of SSA, and three SSA blends (mass proportions: 20/80, 50/ 50 and 80/20). The polishing trends were captured by measuring the British Pendulum Number (BPN) at hourly intervals for 9 h. The laboratory polishing trends suggested that the SSA blending resulted in improved polishing resistance. Based on the polishing trends observed in the laboratory, a suitable mathematical form was selected to model the aggregate polishing. The transfer functions (or shift factors) for the field model were derived by comparing the laboratory polishing with the field polishing trends. The field polishing trend was captured by BPN collected over 3 years at selected locations on two pavements with stone matrix asphalt (SMA) surfaces course mix that were produced with the same aggregates tested in the laboratory. The prediction results from the field BPN deterioration models showed good consistency between field observations and model response values. Using the derived shift factors and laboratory BPN deterioration model parameters, field models for BPN deterioration were developed based on which life prediction of pavement with SMA surface can be made. Field BPN deterioration models suggest that blending of SSA prolongs the residual life up to 10 % depending on the blend proportion and threshold BPN criteria.