Study on grading envelope of AC-16 asphalt mixture based on rutting resistance performance
In this paper, the coarse aggregate packing density tests are studied on different proportion the various particle sizes over 4.75mm, and the demarcation point between coarse and fine aggregate of AC-16 asphalt mixture is 4.75mm, the optimum grading of coarse aggregate is determined by the minimum voids in mineral aggregate. Freeze-Thaw Split and Rutting are tested on 9 kinds of grading AC-16 asphalt mixture with different size and proportion fine aggregate. The results show that the percent passing 4.75mm sieve has affected significantly on the high-temperature rutting resistance and water stability of the asphalt mixture. Based on laboratory test results and grading application experience, it is proposed that the engineering design grading envelope of AC-16 asphalt mixture adapted to the summer hot climates characteristics, which improved the rutting resistance capability of asphalt pavement in hot areas during summer.
Research on Design Method of Multilevel Dense Built-in Gradation
The design system of multilevel dense built-in gradation(MDBG) consisting of coarse skeleton structure and fine skeleton structure was presented on the stage filling theory and particle interfering theory as design basis and the Bailey method as test criterion.The system included coarse aggregate grading design,fine aggregate grading design,synthetic aggregate grading design and checking design gradation by Bailey method.The percentage passing of(0.075 mm) on Bailey method was as a test index,which perfected the evaluation to critical sieve percentage passing of design gradation.Furthermore,the test criterion was afforded to evaluate the gradation in MDBG-16.
LTPP SEASONAL MONITORING PROGRAM: INSTRUMENTATION INSTALLATION AND DATA COLLECTION GUIDELINES. FINAL REPORT
This report describes the operation theory, installation procedures and operation guidelines for instrumentation selected to monitor changes in internal pavement moisture and thermal regimes, frost/thaw conditions, and external climate at test sections in the long-term pavement performance seasonal monitoring study. The instrumentation includes time domain reflectometry to measure moisture content of unbound materials, thermistor sensors to measure pavement temperature gradients and air temperature, electrical resistivity probes to measure frost locations, a piezometer to measure the depth of ground water table and tipping-bucket rain gauge to measure precipitation. These measurements of the external climate and the resulting changes in the pavement material will be coupled with monthly or more frequent deflection measurements, seasonal roughness measurements, elevation profile and distress surveys to study the cause and effects of seasonal changes in pavement structural response. Guidelines and procedures for the collection of these data are also described in this report.