Cement kiln dust (CKD) is the by-product of cement manufacturing. It is collected using air pollution control devices (APCDs) also known as electrostatic precipitators in the form of flue dust to minimize environmental hazards. This study investigates the potential use of CKD as a filler material and its novel antistripping properties on recycled asphalt pavement (RAP). CKD's chemical properties, make it desirable for improving stripping resistance of asphalt in areas prone to high rainfall or moisture exposure, but its application in RAP remains a grey area to explore. Its dual role in improving both adhesion and mechanical properties of asphalt makes it particularly advantageous, in terms of sustainability, cost and resource efficiency. The rising production cost, environmental safety concerns, and the push towards sustainable consumption/production seek alternatives for traditional antistripping agents for asphalt production, thus, CKD. This study prepared dense-graded asphalt concrete with nominal maximum aggregate size (NMAS) of 14 mm with 1%, 3%, and 5% of CKD by weight of RAP according to Malaysian standard. A total of five (5) asphalt concrete (AC14) mixtures were produced with an optimal 3% CKD used in the modified mixtures at the optimum binder content (OBC). The antistripping properties of CKD in hot mix asphalt (HMA) were assessed through indirect tensile strength test (ITS), indirect tensile stiffness modulus (ITSM) and boiling tests on the asphalt mixtures. In addition to the physical, mechanical, chemical, and structural/morphological tests, the safe inclusion of CKD in terms of heavy metals was evaluated by applying toxicity characteristic leaching procedure (TCLP) test. The findings confirm that CKD meets ASTM C150 standards for type II and type IIA hydraulic cement for use as a filler in asphalt. The fatigue cracking resistance, antistripping resistance in terms of the tensile strength ratio (TSR) & indirect tensile stiffness modulus (ITSM) tests indicated that CKD modified RAP mixes performed better than the control (CNTRL), RAP only and CKD modified RAP mixes. It also compares favourably with CNTRL + CKD mixture. Ultimately, the boiling test results indicated that CKD blended RAP mix surpassed the minimum 80% TSR for moisture damage resistance.

In this paper, the drained shear behavior of cement-stabilized recycled asphalt pavement (RAP)-lateritic soil blends is presented. The marginal lateritic soil was replaced by RAP to reduce the fine content and then stabilized by Portland cement for ground improvement and pavement applications. The effect of cement content and RAP content on the shear behavior of RAP-soil samples was evaluated through a series of drained triaxial test. The result indicated that RAP replacement ratio, cement content, and effective stress significantly affected the drained shear of RAP-soil samples. The shear strength increased with cement content and RAP content. However, the excessive RAP replacement ratio results in the reduction of peak shear strength. The brittle to ductile transition was found when effective confining pressure increased. RAP replacement increased the maximum volumetric compression and the dilatation rate of the blends as the inclusion of compressible asphalt binder increased the ductility of RAP-soil samples. The stress-dilatancy behavior of RAP-soil samples was similar to that of medium to dense soil. The stress ratio and dilation significantly depended on RAP replacement ratio, and cement content. The dilation was suppressed when effective confining pressure increased. Row's stress dilatancy equation can model the stress-dilatancy behavior of unstabilized and stabilized RAP-soil samples.