Effect of Nanoclay on Physical and Rheological Properties of Waste Cooking Oil–Modified Asphalt Binder

Abstract

The use of waste cooking oil (WCO) and nanoclay (NC) in the modification of asphalt binder can produce sustainable material for paving applications. This study evaluated the change in physical and rheological properties attained by modification of a conventional asphalt binder using varying percentages of WCO and NC; 0%, 2.5%, and 5% WCO was used to modify a VG 30 binder, followed by reinforcement using four different dosages of montmorillonite NC (0%, 2%, 4%, and 6%). A total of 12 combinations of asphalt binders were produced (VG30, 2NC, 4NC, 6NC, 2.5WCO, 5WCO, 2.5WCO2NC, 2.5WCO4NC, 2.5WCO6NC, 5WCO2NC, 5WCO4NC, and 5WCO6NC) and subjected to physical (penetration, softening point, viscosity, and temperature susceptibility) and rheological [high-temperature performance grading (PG), multiple stress creep and recovery (MSCR), and linear amplitude sweep test (LAS)] measurements. The physical and rheological measurements showed that the use of NC in WCO-modified asphalt binder could reverse the softening effect caused by the inclusion of WCO in VG 30. At 50°C and 60°C, 2.5WCO with 4% and 6% NC had higher values of percentage recovery (R) compared with VG 30. It was found that the use of NC insignificantly increased the strain susceptibility of the asphalt binders at intermediate temperatures for all WCO levels. Statistical analysis revealed that the effect of modification on unrecoverable creep compliance is less significant than the change in R for a temperature range of 40°C–70°C. The significance of modification at intermediate temperatures was not consistent and clear. A simple cost–benefit analysis was proposed, which indicated that 2.5WCO6NC is the optimum combined blend for obtaining higher benefits relative to the cost of modification.