The Verification And Improvement On Asphalt Pavement Low Temperature Cracing Prediction Model Of AASHTO

Currently, low-temperature cracking of asphalt pavement has been a troubling problem to domestic and foreign road workers. The emergence of low-temperature cracking not only affects the performance of asphalt pavement, but also accelerates damage of roads, thus it can severely reduce the service life of roads. Therefore, to guarantee the quality of the road surface, it is an important mission to improve the low-temperature anti-cracking property of asphalt pavement.In order to effectively improve the low-temperature anti-cracking performance of asphalt pavement, a reasonable choice of materials and structural design are needed to reduced the damage caused by low-temperature cracking. However, there is no unanimous system to evaluate the low-temperature performance. For this reason, based on the validation of cementing material low temperature design index of Superpave and NCHRP1-37A prediction model, a new estimation model on the low-temperature performance of asphalt mixture is proposed to apply to Northeast China. The main tasks are as follows:Take the actual crack situation of ChangPing highway for example, the pavement structure core samples in low temperature fracturing test and low temperature fracturing creep test are conducted to verify the relationship between splitting strength and Creep strength degree modulus of the asphalt and the actual crack relationship, respectively.Based on the test of the recycling asphalt rheological index, we verify the correlation between the asphalt creep strength and the actual situation of surface crack; and suggest that an appropriate increase in bending beams of the test of rheological instrument testing temperature is appropriate for recycling asphalt, the corresponding temperature limit strength degree standards should be do appropriate adjustments.According to NCHRP1-37A method of mechanical experience low temperature cracking prediction model, through the single factor analysis of sensitivity, each effect parameter is acquired, to further instruct the application of engineering and the establishment of the empirical prediction model.Based on the combination of different structure under stress, strain, the space distribution features of the differences, the many factors sensitivity analysis is used to analyze different forms of the surface and different types of the recommended the recommended facing; and the choice of the surface layer materials is a key factor to determine the low-temperature cracking of asphalt pavement, and discuss the strategy to make up for structure combination defects by improving pitch performance. Based on relationship between the predicted results from NCHRP1-37A prediction model and the validation actual cracking condition, this model is proved feasibly to applied in Northeast China, and by the time lag equation, the revised predicted results is also given.On the basis of the fixed Hass empirical prediction model , a new empirical prediction model on low–temperature cracking of the asphalt pavement which applies to Northeast China is established. After the verification by using the revised Mechanics experience method, the predicted results calculated by the new model is proved to be accurate and reliable.A comprehensive validation analysis is conducted to estimate the asphalt and asphalt mixture low temperature performance evaluation index; and reviews on the asphalt pavement materials and the structure design of the performance standards for the construction of the index are proposed. They provides necessary theoretical support on the asphalt pavement design method.