ASSESSING TENSILE STRENGTH AND TEMPERATURE SUSCEPTIBILITY OF ASPHALT CONCRETE

In this study, the impact of filler type and aggregate gradation on tensile strength and temperature susceptibility of asphalt concrete were investigated. Two types of aggregate gradation, representing SCRB and Road Note 31 specifications, usually used for asphalt concrete wearing course, have been implemented in the construction of twelve roller compacted slab samples. Asphalt cement of (40-50) penetration grade, and Limestone dust and coal fly ash were implemented as a mineral filler. The optimum asphalt content of each type of mixtures was determined using Marshall Mix design method. Seventy-two Core specimens were obtained from the slab samples. Cores were tested for indirect tensile strength (ITS), at three testing temperatures of (0, 20, and 40°C). The temperature susceptibility (TS) for each mix was also determined. It was concluded that decreasing the testing temperature led to increased ITS for all types of mixtures. ITS increases when the asphalt content was increased at (20 and 0 ˚C), while at 40 ˚C, ITS decreases when the optimum asphalt content was increased or decreased. The Road Note 31 gradation shows more resistant to tensile stress than SCRB gradation at low temperature (0 ˚C), while at other testing conditions, SCRB gradation shows more resistant to tensile stress than Road Note 31. Coal fly ash shows more resistant to tensile stress than limestone dust when used as a mineral filler at different testing conditions. The results of temperature susceptibility (TS) test showed that Coal fly ash was influenced by temperature more than limestone dust. The SCRB gradation was also influenced by temperature changes more than Road Note 31 gradation.