Effect of Wet-Dry Cycles on Resilient Modulus of Class C Coal Fly Ash-Stabilized Aggregate Base

A laboratory study was undertaken to investigate the effect of wet-dry (W-D) cycles on low-quality aggregates stabilized with Class C coal fly ash (CFA). Resilient modulus (M r ), unconfined compressive strength, and elastic modulus were used to evaluate this effect. Cylindrical specimens stabilized with 10% CFA, cured for 3 and 28 days, and subjected to different W-D cycles were tested. The M r values of 28-day-cured specimens increased as W-D cycles increased up to 12, beyond which a reduction was observed. For 3-day-cured specimens, M r increased with the number of W-D cycles. W-D action produced a greater detrimental effect on 28-day-cured specimens than on 3-day-cured specimens. The M r values of 28-day-cured specimens subjected to 30 cycles were approximately 5% lower than the corresponding M r values of specimens without any W-D cycles. The M r values of 3-day-cured specimens subjected to 30 W-D cycles, however, increased approximately 55% compared with the corresponding M r values of specimens with no W-D cycles. Also, it was found that 12 to 30 W-D cycles could be considered adequate to have a noticeable negative effect on 28-day-cured specimens; however, more than 30 cycles are needed for 3-day-cured specimens. Additionally, the positive effect of curing time was more dominant on 3-day-cured specimens, and the detrimental effect of W-D cycles was more influential on 28-day-cured specimens.