Mechanical properties of concrete containing recycled asphalt pavements

Abstract

Recycled asphalt pavement (RAP) is the removed and/or reprocessed pavement material containing asphalt and aggregate. The use of RAP in asphalt pavement has become common practice in the construction of new, and reconstruction of old, hot-mix asphalt (HMA) pavements. However, little research has been done to examine the potential of incorporating RAP into Portland cement concrete (PCC) to replace virgin aggregate. In a previous study by the first two of the current authors, laboratory-prepared RAP was used to investigate the potential use of RAP in PCC. The present study focused on the evaluation of mechanical properties of PCC made with real RAP materials through laboratory experiments. Two types of RAP materials (coarse and fine RAP) were used to replace an equal amount of virgin coarse and/or fine aggregate. Silica fume and high-range water-reducing agent (HRWRA) were also added into concrete mixtures to minimise the strength loss resulting from the incorporation of RAP. A total of 17 concrete batches were cast and evaluated for compressive and split tensile strengths, static compressive modulus of elasticity and toughness index. Test results indicated that there was a systematic reduction in the strengths and elastic modulus as well as an increase in the toughness index with the increase in RAP content. While the addition of HRWRA into the matrix improved the mechanical properties of concretes containing RAP, addition of silica fume did not.