Characterization of cement-kiln-dust stabilized base/subbase aggregate.

Abstract

In this study, a laboratory testing program was undertaken to determine the resilient modulus and other properties of a cement-kiln-dust (CKD) stabilized aggregate that are important to the design and rehabilitation of roadway pavements. Meridian limestone aggregate, which is considered to be of substandard quality and unsuitable for highway base course was tested for its resilient modulus (RM) value in raw and stabilized forms. Effect of freezing/thawing and wetting/drying cycles on the RM values was investigated. Flexural strength of CKD-stabilized aggregate was also examined using one third point beam test method.

It is observed that there is a continuous increase in RM value with increasing amount of CKD and curing time. The 28-day cured aggregate stabilized with 15% CKD has a range of RM values from 109 MPa to 683 MPa, representing more than 120% increase over the raw aggregate. The CKD-stabilized aggregate can develop a small amount of flexural strength. The RM values decrease substantially with increasing number of freezing/thawing and wetting/drying cycles. The reduction in RM value due to freezing/thawing and wetting/drying cycles reach more than 50%. The unconfined compressive strength (UCS) and elastic modulus (EM) increase with increasing CKD content and curing period. Microanalyses including SEM and XRD analyses revealed that hydration products and decrease in voids may be responsible for increase in strength of CKD-stabilized aggregate.