Modification Mechanism and Performance of Qingchuan Rock Asphalt–Modified Asphalt

Abstract Using Esso AH-70 asphalt as the base asphalt, the modification mechanism for Qingchuan rock asphalt–modified asphalt was studied using asphalt component tests, differential scanning calorimetry, infrared spectrometry, and fluorescence microscopy. The performance of the Qingchuan rock asphalt–modified asphalt was analyzed based on modified asphalt index tests, the dynamic shear rheometer test and the bending beam rheometer test. Performance verification of the Qingchuan rock asphalt–modified asphalt was conducted using the rutting, mechanical property, small-beam bending, freeze-thaw split, indirect tensile fatigue, and small-sized acceleration loading tests. The results indicate that rock asphalt asphaltene has a high content of heteroatom groups as well as strong aromaticity and polarity. After the base asphalt is modified with rock asphalt, its microstructure is changed. The temperature sensitivity of rock asphalt–modified asphalt is decreased, and the temperature stability and water stability are strengthened. The rock asphalt modifier can obviously improve the antifatigue performance and high-temperature stability of its asphalt mixture. The dynamic stability of AC-20 with an 8 % rock asphalt content is 4,769 times/mm, which is 3.05-fold higher than the dynamic stability of the base asphalt. Under the same experimental conditions, the fatigue life of AC-16 with an 8 % rock asphalt content is 18-fold higher than that of its base asphalt mixture. Small-sized acceleration loading tests confirm that the antifatigue performance and antirutting performance of a 10 % rock asphalt–modified asphalt mixture increase by 120 % and 233 %, respectively, over those of its base asphalt. Additionally, the antifatigue and antirutting performances exceed those of the styrene-butadiene-styrene–modified asphalt mixture. Qingchuan rock asphalt can improve the comprehensive performance of an asphalt mixture, and it can be used in nonextreme low- temperature environments.