Abstract
Resilient modulus (Mr) is one of the most important parameters in the design of highway pavements, and it is an indicator of the behavior of material as a component of the pavement system which is subjected to vehicular loading. To improve on the quality of the aggregate, cement kiln dust (CKD) is being proposed as an additive to an aggregate intended for base/subbase construction of highway pavements. A series of triaxial cyclic loading tests were performed in accordance with the AASHTO T294-921 procedure to investigate effects of CKD amounts and curing time on the resilient modulus of the aggregate. It is found that the Mr values increase with the CKD amount and with curing time within a certain period. The aggregate stabilized with 15% CKD is found to be best suited for base/and subbase with regard to the Mr value. For 7-day and 28-day curing periods, the increase in Mr values with respect to the raw aggregate can be up to 70% and 120%, respectively ; however, the difference between the 28-day and 90-day stabilized aggregate is minimal. Scanning Electronic Microscopy (SEM) tests and X-ray diffraction (XRD) tests were performed to reveal the mechanism of stabilization. It is found that the increase in resilient modulus is the result of hydration of the CKD and filling of the intracluster voids of the fine particles of the aggregate.
