Effect of Waste Perlite Powder as a Replacement for Natural Filler on the Mix Design and Performance Properties of Slurry Seal Surface Treatment

The reuse of industrial waste materials in infrastructure projects presents a promising approach to reduce natural resource consumption and minimize environmental impacts. This study examines the performance of waste perlite powder (WPP) as a sustainable alternative to conventional natural fillers in slurry seal mixtures. Five mix designs were prepared by partially replacing the natural filler with WPP at 0%–10% total aggregate weight, corresponding to 0%–100% replacement of the original filler (constituting 10% of the aggregate). The mixtures were evaluated using a comprehensive set of standardized tests, including mixing time, wet cohesion, sand adhesion, wet track abrasion test (WTAT), and loaded wheel tracking (LWT), as well as determining the optimum residual bitumen content. The WPP at 75% (WPP75) achieved 28.4 kg·cm of wet cohesion at 60 min, a 16% reduction in sand adhesion, and a greater than 50% improvement in abrasion resistance (355 g/m 2 versus 728 g/m 2 in the control). Wheel tracking tests indicated reductions of 25.7% and 42.3% in vertical and lateral displacements, respectively, highlighting improved deformation resistance. A higher WPP content increased water demand; all mixtures retained acceptable mixing times (> 180 s). Overlay analysis of WTAT and LWT results identified an optimal residual bitumen range of 8.03%–8.66%, with WPP75 showing the highest bitumen demand. A two-way analysis of variance showed that WPP content, bitumen dosage, and their interaction significantly affected performance, accounting for most of the response variability. Incorporating up to 7.5% WPP is technically viable and environmentally advantageous, enhancing the durability, cohesion, and sustainability of slurry seal pavements.