Developing a Premium Cementitious Filler Incorporating High Content of Sewage Sludge Fly Ash

Cold bituminous emulsion mixture (CBEM) is a sustainable replacement to the conventional hot mix asphalt (HMA) due to environmental and safety issues associated with the use of the latter. However, CBEM experiences some drawbacks including long-term curing, low strength in the early days and high air voids content; thus, it needs from 2 to 24 months to reach its ultimate strength. Accordingly, the applications for CBEMs have been limited to low- /medium-trafficked roads, footways and reinstatements. This study aimed at developing a new cementitious material incorporating a high volume of sewage sludge fly ash (SSFA) with low ordinary portland cement (OPC) content and carbide lime waste (CLW), to replace the traditional limestone filler in CBEM. A significant improvement has been shown in the performance of the developed CBEM in terms of indirect tensile stiffness modulus (ITSM) and microstructure analysis compared to the conventional CBEM incorporating limestone filler. Furthermore, the developed mixture has being comparable to the mixtures including OPC and the conventional HMA. A considerable alteration in the microstructure components over the curing ages has been developed, which is confirmed by the creation of cementitious hydration products using scanning electron microscopy.