Indirect tensile strength assessment of hot mix asphalt subjected to solvent soaking at high-temperature

Abstract

The objective of this paper is to assess the effect of solvent (benzene) on the indirect tensile strength (ITS) of the Hot Mix Asphalt (HMA) during the peak summer of Iraq (60 C°) when dropped on an asphaltic road as a measure of durability. Two conditioning cases are applied, the (unconditioned case) where the samples are tested in dry condition at 25 °C and (the conditioned case by soaking in benzene for 30 minutes after 30 minutes conditioning in water bath at 60 °C) the conditioned case prepared to simulate an existing road at peak summer in Iraq. Thirty-six marshal specimens are prepared for three different air void content 4, 6 and 8%. Two asphalt types are used neat (AC 40-50) and modified (AC 40-50 + 4%SBS) with three different filler content 6%, 8% and 10%. The tensile strength ratio (TSR) results show clearly defect in conditioned samples where the TSR decreased about 8%, 10% and 17% for samples used neat asphalt with 4%, 6% and 8% air void content respectively. On the other hand, the conditioned samples using modified asphalt showed better resistance where only 5%, 7% and 10% decrease in TSR. Nevertheless, the seriousness effect of benzene on the durability of HMA using modified asphalt with 10% filler content at 4% air void content provides 94% TSR while the minimum TSR is 82% for modified asphalt with 6% filler content at 8% air void content. On the other side, the minimum TSR results are observed on samples using neat asphalt regardless the filler and air void content the TSR are less than 80% which is not acceptable according to the State Corporation of Roads and Bridges (SCRB) limits. As a result, it is recommended to use modified asphalt to sustain the durability for Iraqi roads.