Physico-chemical properties and overall asphalt mixture performance prepared with lime kiln dust as an alternative mineral filler

The global asphalt industry seeks sustainable alternatives to reduce its environmental footprint. This study investigates the potential of an industrial by-product, namely lime kiln dust (LKD) as an alternative mineral filler for asphalt mixtures, focusing on its impact on physico-chemical properties and overall mixture performances. Collaborative efforts involving university and industry laboratories were undertaken from sample preparation to performance testing and to investigate the potential of LKD-modified mixture. Through a comprehensive laboratory investigation involving mechanical tests (Marshall stability, indirect tensile strength, resilient modulus, dynamic creep, and Hamburg wheel tracking) and microstructural analysis (field emission scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and x-ray diffraction), LKD-modified mixtures demonstrated superior performance. The main quantitative results show that the AC14 + 2%LKD mixture exhibited a 27% increase in resilient modulus (5549 MPa versus 4375 MPa) and a 58% higher Dynamic Stability (4167.94 versus 2630.06 cycles mm⁻¹) compared to the standard AC14 + 2%OPC mixture. Furthermore, LKD mixtures showed enhanced moisture resistance, with the AC20 + 2%LKD mix achieving a tensile strength ratio of 1.21, indicating superior moisture damage resistance compared to conventional fillers. Critically, the AC14 + 2%LKD mixture demonstrated a 44% reduction in rut depth (2.51 mm versus 4.50 mm) compared to the traditional AC14 + 2%OPC mixture. The study concludes that LKD is not only an eco-friendly filler aligning with circular economy principles but similarly a technically superior one that significantly improves rutting resistance and durability of asphalt pavements.