Investigative tests on the performance of asphaltic mixtures modified by additive combinations (hydrated lime and polypropylene)

Abstract

Scientists and engineers are constantly trying to improve the performance of asphalt mixtures, and a wide range of modifiers are utilised to enhance HMA characteristics against damage such as rutting, aggregate stripping, and cracking.The major objective of this research is to evaluate the performance of flexible pavement using asphalt from the Al-Daurah refinery with two locally additive, hydrated lime and polypropylene. Hot mix asphalt specimens were prepared with aggregate, of nominal maximum size 25 mm (base course) and 19 mm (binder course).Cement is usually utilised as an HMA filler, and a percentage of Portland cement was used in this work, at 5% for the base course and 6% for the binder course. Polypropylene was used as additive with percentages of 1, 2, and 3% by weight of asphalt, and hydrated lime was used in a dry state at a percentage of 1% by weight of aggregate as a part replacer of filler.The main mechanical characteristics of asphalt mixtures were evaluated using the Marshall index of retained strength and indirect tensile strength tests. Using hydrated lime and polypropylene caused the results of Marshall tests and indirect tensile tests to increase by 1.3 and 1.5 times, respectively, compared with the control mixture, while the index of retained strength test increased by 1.3 times compared with the control mixture. In particular, the addition of a combination of 1% hydrated lime by weight of aggregate and 2% polypropylene by weight of asphalt-to-asphalt mixtures satisfied the requirements for stability, moisture sensitivity, and indirect tensile strength.