Evaluating the properties of hot asphalt mixtures modified by Metakaolin

Abstract

The mineral filler has an important role in filling the voids between aggregates inside the asphalt matrix. This study investigates the effect of using Metakaolin (MK) as a modifier on the mechanical properties of hot mix asphalt. MK was added to the mixtures as a part of the filler used. As known, the hot mix asphalt (HMA) consists of coarse aggregate, fine aggregate, filler material, and asphalt binder with or without existing modifiers. The components of the HMA were subjected to validation tests to check the validity of the materials for producing HMA The asphalt binder used was bitumen 60/70. Tests performed on bitumen were penetration test, softening point test, flash and firing point test. The optimum asphalt content based on the designed control mix was 5.2%. the control mix has no content of MK. MK was added as a partial replacement of filler used (limestone powder). Mk was added to the HMA by replacing 20%, 40%, 60%, 80%, and 100% of the filler. A comparative study was performed to evaluate the effects of HMA modification by MK. Marshall quotient (MQ) increases by 10.37% for the mix modified by 40% MK. MK has significant effects on the indirect tensile strength (ITS).