Mechanical performance of concrete pavement with recycled asphalt powder and optimized aggregate gradation

Abstract

The construction sector is a major contributor to environmental degradation, with cement manufacturing accounting for a significant portion of global CO 2 emissions. This study explores the partial replacement of cement with reclaimed asphalt pavement (RAP) powder as a sustainable alternative to conventional concrete production, a strategy that remains relatively underexplored in literature. Concrete mixes containing 2.5%, 5%, 7.5%, and 10% RAP powder replacing cement by volume were designed accordingly. The tarantula curve methodology was adopted to optimize aggregate gradation enhancing mix performance. Mechanical properties, including compressive, flexural, and tensile strengths, alongside workability and durability, were evaluated. Exploratory models were developed to examine the relationship between RAP content and compressive strength with flexural strength, tensile strength, and elastic modulus. Thermogravimetric analysis (TGA) indicated negligible pozzolanic activity of RAP powder of 8%. However, the results indicate that at 5% RAP replacement, the concrete achieved mechanical performance comparable to that of the control mix (0% RAP) suggesting a useful micro filler effect at his level. A Cradle-to-Gate Environmental Assessment using a 1 m 2 concrete slab functional unit showed that replacing 5% and 10% of cement with RAP powder reduced CO 2 emissions by 4.85% and 9.69%, and embodied energy by 4.72% and 9.29%, respectively. Environmental benefits stem mainly from reduced cement production emissions.