Application of Nano CaO and Nano CaCO3 in HMA in order to improve the Strength against Cracking and Moisture Susceptibility- an Experimental Study

Thermal cracking and moisture sensitivity are two of the most important failures that face asphalt pavement with serious threats during the operation period. In this research, the effect of nano CaO and nano CaCO3 additives to HMA has been evaluated in order to improve their performance against cracking and moisture sensitivity. In order to achieve the goals of this research, bitumen was mixed with 0.9% of nano CaCO3 and 1.5% of nano CaO, and to evaluate the functional characteristics of HMA samples containing nano additives, semicircular bending (SCB) tests were performed in three The temperature was -5, -10 and -15 °C, and modified Latman was performed at two temperatures of 10 and 20°C. According to the SCB and ITS test results, the best performance and the highest resistance is related to the sample containing 1.5% Nano CaO, which is about 22% more resistant to thermal cracks and about 6% less sensitive to moisture than the control sample. Based on the SCB test results, it can be seen that with the increase of Me from zero to about 0.4-0.6 when the loading is a tensile-shear combination, the fracture toughness will decrease and then increase when the loading goes to pure tension. Such that the greatest resistance to cracking occurs in pure tension.