Effect of Temperature on Compressive Strength of Geopolymer-Stabilized Reclaimed Asphalt Pavement for Roadway Base Applications

Abstract

This study investigates the effect of temperature on the compressive strength of reclaimed asphalt pavement (RAP) stabilized with geopolymer derived from coal ash as a potential material for roadway base. The Unconfined Compressive Strength (UCS) of RAP specimens modified with geopolymers from fly ash and bottom ash was analyzed. The geopolymerization process was activated using an alkaline solution composed of sodium hydroxide and sodium silicate. The specimens subjected to heating-cooling cycles curing (room temperature, 40°C, and 70°C), where the specimens underwent alternating cycles of 12 hours of heating and 12 hours of resting at room temperature, continuing until the curing period reached 7 days. The results indicate that RAP stabilized with geopolymer from fly ash and bottom ash achieved a UCS greater than 40 kg/cm² after 7 days of curing, meeting the criteria for roadway base applications. The proportions of fly ash and bottom ash significantly influenced the UCS, with an increase in fly ash content enhancing compressive strength, while a higher bottom ash proportion resulted in a decrease. Furthermore, the UCS of specimens subjected to heating-cooling cycles at 40°C exhibited no significant difference from those cured at room temperature. However, curing at 70°C resulted in an increased UCS for all specimens compared to room temperature curing, suggesting that higher curing temperatures contribute to enhanced compressive strength.