Assessing the Effect of Steel Slag and Reclaimed Asphalt Pavement on Mechanical Properties and Pollution of Roller Compacted Concrete Pavement

In recent years, due to the higher cost of pavement construction and environmental considerations, various waste and recycled materials have been used in concrete and Roller Compacted Concrete (RCC) mixtures. This study investigates the effect of partial and full replacement of natural aggregates with steel slag as a by-product of the steel industry and Reclaimed Asphalt Pavement (RAP) as a waste of the road pavement construction industry, on the mechanical and environmental properties of RCC pavements. For this purpose, compressive strength, indirect tensile strength and three-point bending tests were conducted on 7 and 28-day samples. Three-point bending test was used to obtain flexural strength, toughness, and energy absorbency. Also Cantabro abrasion test and Toxicity Characteristic Leaching Procedure (TCLP) were conducted on 28-day samples. The results showed that the compressive strength, tensile strength and flexural strength of RCC pavement reduced by replacing natural aggregates with steel slag and RAP. In the meantime, the effect of RAP on reducing mechanical properties of roller concrete is more pronounced. Increasing the content of steel slag and RAP increases the toughness, as well as the energy absorbency capacity of the specimens despite the decrease in the maximum load. On the other hand, the abrasion resistance of the roller concrete mixture increases, with increasing steel slag. Also, according to the results of this study, the mixtures containing up to 50% steel slag or combined steel slag and RAP, met the regulatory requirements. By incorporating 25% steel slag and 25% RAP as substitutes for natural aggregates, compressive, tensile and flexural strengths decreased and toughness increased up to 24%, 34%, 21% and 13%, respectively. Thus, the waste materials used in this study, are usable in RCC because of their satisfactory results and economic-environmental advantages.