Laboratory evaluation of Nano Al2O3 effect on dynamic performance of stone mastic asphalt

A part of different countries' budget in the world annually is spent on the restoration and reconstruction of pavements damages. Hence, by increasing the quality of hot mix asphalt, the pavement researchers are constantly trying to improve the quality of hot mix asphalt, greatly reduce the incidence rate of damages in the roads and delay the incidence time as much as possible. Many studies show that the quality of hot mix asphalt can be improved by using additives. Nano Al2O3 is studied as an additive in this research and also, in order to improve the hot mix asphalt strength against the damages, the type of stone mastic asphalt is examined. Stone materials gradation used in this study is the average gradation proposed by Asphalt Pavement Regulation of Iran Roads (Publication 234) for stone mastic asphalt with a maximum aggregate nominal size of 20 mm. The bitumen consumed is bitumen 60-70 in Tehran Pasargad Oil Processing Complex. In order to prevent the draindown phenomenon in stone mastic asphalt which occurred according to the space between aggregates, the cellulose fibers with the amount of 0.3% hot mix asphalt weight are used to produce the hot mix asphalt. The effect of Nano Al2O3 additive on dynamic performance of stone mastic asphalt is investigated through dynamic creep test, wheel track test and indirect tensile fatigue test. Results show that addition of different percentages of Nano Al2O3 is capable to improve the dynamic performance of stone mastic asphalt, significantly.