Moisture Resistance of Olive Husk Ash Modified Asphalt Mixtures

In agricultural nations such as Jordan, olive oil production generates substantial quantities of a byproduct known as olive husk. Traditionally utilized for heating purposes, olive husk is now being employed in the production of cleaning solutions and cosmetic products. This study investigates the potential use of olive husk ash (OHA) as a filler in bitumen, when combined with aggregate to produce asphalt mixtures typically employed in road pavement construction. The impact of moisture on the properties of asphalt mixtures containing OHA filler was examined using the Marshall Stability test method. OHA was incorporated as a replacement for bitumen at varying volumes (0, 5, 10, 15, 20%). The optimum bitumen content was added to limestone aggregate to prepare asphalt mixture specimens. Furthermore, the effect of Dryback on the properties of asphalt mixtures was assessed. Findings indicate that the inclusion of OHA in bitumen (by volume) reduced the moisture resistance of specimens, with an optimal performance observed at 10-15% replacement. Additionally, it was found that the moisture effect on asphalt mixtures was reversible, and the observed degradations in strength and stiffness after wet conditioning were not predominantly due to the adverse effects of water. Consequently, the utilization of OHA as a pavement material in the field could potentially reduce production costs and enhance performance, leading to notable environmental benefits.