Performance and environmental assessment of microsurfacing mixture using the granulated Blast-Furnace Slag Powder (GBSP) as potential recycled filler

Abstract

One of the best methods for preventive maintenance of roads is using microsurfacing. The present research focuses on the effect of using Granulated Blast-Furnace Slag Powder (GBSP) as the replacement for Natural Aggregate Filler (NAF) on the performance of microsurfacing mixture. For this purpose, tests such as Wet Cohesion Test, Wet Track Abrasion Test, Loaded Wheel Test-Displacement, and Loaded Wheel Test-Sand Adhesion were performed in five groups. These groups consisted of microsurfacing mixtures containing 10 % NAF (control mixture), 7.5 % NAF + 2.5 % GBSP, 5 % NAF + 5 % GBSP, 2.5 % NAF + 7.5 % GBSP and 10 % GBSP based on the total weight of aggregates. Next, to evaluate the environmental impact of the mixture, the Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) tests were investigated. The results of the performed tests on the specimens showed that the mixtures containing GBSP improved the microsurfacing mixture performance. Among the mixtures, the one containing 10 % GBSP caused increase in the cohesion, reduction of the vertical Displacement, and reduction in the potential of bleeding by 35 %, 57 % and 48.5 %, respectively. Also the moisture damage resistance of all the mixtures containing GBSP was within the allowable limits of the standard (ASTM D6372). The results of the leaching tests also exhibited that the specimens containing GBSP were environmentally friendly mixtures. So that leakage of all the studied heavy metals was lower than the allowable limits and using them in microsurfacing as replacement for filler up to 10 % is acceptable.