Performance of Stabilized Aggregate Base under Flexural and Compressive Cyclic Loading

A laboratory study was undertaken to evaluate the behavior of a low quality aggregate base stabilized with Class C fly ash (CFA) under cyclic and static flexural loading to evaluate its resilient modulus (Mr) and flexural strength (FS), respectively. Prismatic specimens were molded and cured for 1 hour, 3 days, and 28 days. To evaluate the effect of CFA on the flexural strength two raw beams were molded using unstabilized aggregate. However, both of these beams could not be tested since they failed under their self weights, due to negligible flexural strength. Results of the stabilized aggregate specimens show that the FS and Mr values for cured specimens increased as the curing time increased from 1 hour to 28 days. However, the percent increase in those properties as curing time increased from 1 hour to 3 days is higher than the corresponding percent increase from 3 to 28 days. Such an increase is due to the formation of cementitious products. The resilient modulus in flexure decreased as the flexural stress increased due to large strain levels in a flexural test. Comparatively, the resilient modulus in compression increased with the deviatoric stress. The FS was approximately 8 to 10 times lower than the unconfined compressive strength. Knowledge of such differences in behavior may be of vital importance in designing flexible pavements having a stabilized aggregate base.