Curing conditions effect on the stabilization of recycled asphalt pavement with alkali-activated metakaolin and rice husk ash-derived activator

Abstract

The stabilization of recycled asphalt pavement (RAP) with alkali-activated cement (AAC) is a topic of growing interest for sustainable engineering, especially those containing alternative activators produced from waste. This study evaluated the effect of curing temperature on the stabilization of RAP with a metakaolin AAC and rice husk ash-derived activator for potential use in base and subbase layers in flexible pavement systems. Unconfined compressive strength (UCS), X-ray diffraction, and scanning electron microscopy tests were performed. Higher strength values were associated with higher temperatures and curing times. Curing oven time presented no influence over UCS and mineralogy. Blends cured at 20°C exhibited efflorescence formation and prolonged curing time at high temperatures negatively affected the mechanical performance. Curing temperature of 80°C up to 24 h promoted the formation and uniform distribution of cementing gels and a dense and compact structure, improving the compressive strength.