Employing Natural Bentonite Clay as Partial Replacement of Mineral Filler in Asphalt Mixtures

This study aimed to investigate the performance of asphalt mixtures after natural bentonite clay partial replacement of mineral filler portion of aggregates. Different bentonite contents were used to replace the mineral filler by total weight of its portion of total aggregates, namely, 5, 10, 15, and 20%; additional bentonite contents were conducted for the stability test, namely, 25 and 30%. Marshall stability, flow, bulk density, hydraulic conductivity, and indirect tensile strength (ITS) tests were performed. Results showed that replacing mineral filler by natural bentonite clay in asphalt mixtures leads to the increase of density and stability, which increased to 11.57 kN for mixtures containing 15% bentonite (compared with 9.17 kN for the control specimen), with 23% loss when soaked with water for 24 h. Results indicate an increase in both flow and ITS values and reduction in hydraulic conductivity of the modified mixtures compared with control specimens. (C) 2018 American Society of Civil Engineers.