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

AbstractThe 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.KEYWORDS: Recycled asphalt pavementalkali-activated cementalternative alkaline activatorstrength developmentmineralogymicrostructure AcknowledgementsThe authors wish to explicit their appreciation to National Council for Scientific and Technological Development -CNPq for the support to the research group.Disclosure statementNo potential conflict of interest was reported by the author(s).Authors’ contributionsAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Aednor Antonio Casado Zago and Deise Trevizan Pelissaro. The first draft of the manuscript was written by Deise Trevizan Pelissaro and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. In addition, Francisco Dalla Rosa was responsible for the supervision of the research.Data availability statementSome or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.