Improving the Sustainability of Semi-Dense Asphalt Pavements by Replacement of Recycled Concrete Aggregate Fractions

Waste concrete is one of the most highly produced types of waste in the urban environment and finding a means for its re-use is crucial to making infrastructure sustainable. Semi-Dense Asphalt (SDA) is a type of asphalt mixture, which is commonly used in Switzerland to reduce pavement noise. This study examined the use of various fractions of Recycled Concrete Aggregates (RCA) into SDA mixtures. The virgin aggregates were replaced by RCA in selected fractions of 2/4 and 0.125/2 at 100% and 50%, with only one fraction being replaced for any single mixture. The mixtures were evaluated by volumetrics, indirect tensile strength and water sensitivity (EN 12697-12) in order to assess the effects of each RCA fraction. The results showed that RCA coarse aggregates absorb high amounts of binder, which is not the case for the RCA sand. The ITS results showed increase peak load for the RCA replacement samples but also increased brittleness. The ITSR% was similar to the control for lower fraction of RCA replacement samples, but significantly lower with higher replacement.