Mix design and performance evaluation of microsurfacing containing electric arc furnace (EAF) steel slag filler

Microsurfacing is an important technique for the preventive maintenance of roads. Accordingly, the road construction and urban planning sectors are concerned about the design and optimization of microsurfacing as a type of protective asphalt mixture to achieve a suitable combination of performance and service life. Therefore, the quality and performance of microsurfacing play an important role in the design of such asphalt mixtures. The present research aimed to study the feasibility of using steel slag rather than conventional filler materials (aggregates passing sieve No. 200) in the microsurfacing mix design to improve the ultimate performance of the mixture. Here, we begin by subjecting polymer bitumen emulsions to rheological tests to determine the suitable bitumen emulsion. Subsequently, the microsurfacing mixtures were prepared with five different compositions containing electric arc furnace (EAF) steel slag filler at 0%, 25%, 50%, 75%, and 100% levels as the replacement for the aggregates passing through the 0.075-mm sieve. The asphalt mixtures were tested using the cohesion test, loaded wheel test, and wet abrasion test. The results of the design indicated that the mixtures containing the EAF steel slag satisfied the code requirements, with the mixture containing the EAF steel slag at 50% level producing the best performance among the mixtures. It was also found that the mixture containing 0.65% higher amount of bitumen has the best performance compared to the control mixture to achieve the appropriate adhesion within proper time scale. The results of the tests on the samples showed that the mixtures containing the steel slag filler were well consistent with the bitumen emulsion because of the desirable mechanical, chemical and physical properties. Also, the mixture containing the steel slag at 50% level could improve the microsurfacing performance in terms of curing time, abrasion resistance, bleeding, and vertical displacement by 2.9%, 19.0%, 14.0%, and 31.0%, respectively. (C) 2020 Elsevier Ltd. All rights reserved.