Laboratory and Field Evaluation of Base Stabilization Using Cement Kiln Dust

Abstract

Laboratory and nondestructive field tests were conducted to evaluate the effectiveness of cement kiln dust (CKD) as a stabilizer for a limestone base. The test results showed that CKD has promise as a stabilizer for the base material if it is used properly. The comparative performances of CKD and other traditional stabilizers such as lime, cement, and fly ash were also investigated during laboratory and field testing. The unconfined compressive strength (UCS) increased substantially when the dosage of CKD was increased. The UCS also increased substantially over time because of the formation of more cementitious products through pozzolanic reactions and cementitious material hydrations. The dielectric value measured in the tube suction test is a good indicator of moisture susceptibility of base materials. It increased with increasing amounts of CKD after a short-term curing period; conversely, and beneficially, it decreased because of chemical reactions within specimens after a long-term curing period. Therefore, it appears that the tube suction test is not effective for evaluating moisture susceptibility of CKD-stabilized base materials. The seismic modulus increased substantially with addition of CKD for the same reasons the UCS increased. Conductivity and colorimetry tests indicated that sulfate content increased with the amount of CKD added. A low resistivity value of CKD-stabilized base materials indicated that they cannot be used as backfill material. The field pavement evaluation indicated that the lime-stabilized section exhibited the highest modulus, followed by the CKD-stabilized section. The other three sections yielded similar layer modulus values. In general, the modulus of all sections decreased over time.