Influence of Anti-Cracking Agent on Asphalt Pavement with Cement-Treated Base

The cement-treated base(CTB) has been used successfully to address ever-increasing traffic volume and at locations where subgrade quality is poor, however, one of the main distresses for asphalt pavement with CTB is reflective cracking. An innovative construction methods[Continuous Construction Method(CCM)] was proposed in this paper to mitigate the premature cracking originated from the CTB. The CCM differs from the traditional construction method in the construction process. Traditionally, the CTB need to be cured for 3to 7days after paving to secure strength, this procedure was canceled in CCM and the asphalt mixture was supposed to be paved immediately after the construction of CTB. Anti-cracking agent was developed and added into the cement stabilized base materials to prolong the hydration process and initial setting time of the base materials, thus providing sufficient time for paving the asphalt concrete layer and guaranteeing the asphalt mixture being paved and compacted before the cement stabilized materials hardened. In addition, micro-expansion materials generated from the pozzolanic reaction between cement-treated materials and anti-cracking agent could contribute to reducing the porosity of CTB and the contraction space for drying shrinkage and temperature shrinkage. In this paper, the influences of anti-cracking agent on setting time of cement paste, basic mechanical property and shrinkage property of cementtreated materials were analyzed, and the generation of ettringite from cement system was investigated from the microscopic perspective by the scanning electronic microscope (SEM). The test results indicated that the cement treated materials with anticracking agent have good micro-expansion and densification performance, which significantly reduces the shrinkage caused by the temperature and humidity change, improves the pavement performance of CTB and prolongs the roadway service life. Additionally, test roads were constructed and contrasted to verify the anti-cracking effectiveness of CCM. Pavement performance was monitored for 4 to 5 years after construction. During the evaluation period, both laboratory and field tests were conducted to obtain the strength, bonding condition and cracking rate data. The results showed a superior compositive anti-cracking performance of CCM. Bond strength and shear strength Jia Li, Jianmin Zi, Tao Hu School of Civil Engineering and Mechanics Huazhong University of Science & Technology 1037 Luoyu Road, Wuhan, China Doraemon2012@hust.edu.cn