Alkali Activated Concrete Mixes with Processed Reclaimed Asphalt Pavement

Abstract

This study evaluates the feasibility of using processed reclaimed asphalt pavement for alkali-activated slag concrete (AASC) mixes. A novel alkali and alkali-abrasive method is developed to remove the stiff asphalt layer and puncture the asphalt film engulfed in the Reclaimed Asphalt Pavement (RAP) material. The hydrophobic layer of asphaltic aggregate exhibits poor bond characteristics, significantly affecting concrete strength properties. The influence of processing methods on concrete characteristics was investigated and compared with control mixes. Incorporating processed RAP improved the workability properties and cohesiveness of mixes at different sodium hydroxide concentrations. Beneficiation of processed RAP by alkali and alkali-abrasive techniques increased strength characteristics by 20% and 42% respectively compared to control mixes. Processing RAP using the alkali technique improved workability properties slightly, while the alkali-abrasive technique significantly improved fresh and hardened characteristics due to the removal of the stiff asphalt layer. Fatigue test data were analyzed using a two-parametric Weibull distribution for survival probability. The analysis established that fatigue life at various stress levels for AASC with processed RAP can be described using Weibull distribution. Goodness-of-fit tests validated the distribution model for the statistical description of the fatigue life of various mixes. Based on laboratory tests, alkali-activated mixes developed with processed RAP satisfy requirements for pavement-quality concrete. © The Author(s), under exclusive licence to Chinese Society of Pavement Engineering 2025.