Effects of filler concentration on indirect tensile (IDT) cracking indices in hot mix asphalt at intermediate temperature

Abstract

Mineral fillers are known to affect the cracking properties of hot mix asphalt (HMA) significantly. Therefore, the aim of the study was to investigate the effects of filler concentration on the indirect tensile cracking indices of hot mix asphalt at an intermediate temperature. To make the test samples, the standard 100% limestone filler was substituted with the recycled fillers of hollow concrete block (HCB) powder and brick powder (BP), in three different concentrations (3%, 5%, and 7%). Optimal concentration levels resulted in superior mixes that could sustain pavement service life and environmental friendliness. Mixtures with 100 and 150 mm-diameter specimens were evaluated using the flexibility index (FI), crack tolerance index (CT index), fracture energy index (FEI), toughness index (TI), cracking resistance index (CRI), and fracture strain tolerance (FST) index from IDT test. The results indicate that filler concentrations influence the IDT indices significantly and that the 5% filler mixtures yielded reasonable testing results. The two specimen sizes were found to have moderate to strong correlation coefficient (R2 ) values for the same indices, supporting that both may be used interchangeably to assess cracking resistance in HMA. Thus, using 100 mm-diameter specimens may be used to minimise costs and material quantities.