Huang Xiao-ming

The Development of Recycling Agent for Asphalt Pavement

A type of recycling agent was developed and its use for modifying used asphalt is described. The results show that the viscosity and three main properties of the aged asphalt were remarkably improved. With 5%–7% content of recycling agent, the main properties of recycled asphalt comported with China GB asphalt standard AH—70 and the recycled asphalt concrete could be used as high-grade highway. Furthermore, the recycling mechanism of the aged asphalt is discussed.

Fatigue Analysis of Cement-Stabilized Macadam Using Fracture Toughness

The fatigue life of cement-stabilized macadam specimen beams was analyzed using the fracture toughness index. The damage evolution equation controlled by the tension stress was given, whose coefficients were back-calculated based on the fracture toughness control index using partial fatigue tests data. The fully coupled stress-damage method was used. The result shows that the damage evolution equation based on the fracture toughness control index has better life prediction ability comparing with the S-N equation used usually. The method used in the paper can provide a calculation model to predict the life of practical road structure.

The Damage Analysis of Asphalt Pavement Under Repeated Loads

Generally, the process of pavement deterioration occurs before the macrocrack appearing in asphalt pavement structure. It is always useful to understand the causes of pavement cracking and present preventive measures. In this paper, damage regularity of asphalt pavement under the condition of repeated loading is studied in terms of dynamic damage finite element method. The software ABAQUS was used for calculation and subroutine of damage was obtained by using the interface of the vectorized user material routine. The relationships between the times of loading and the damage degree, maximum tension stress of element and maximum tension strain of element are analyzed and discussed.

Effects of Magnesium Hydroxide on Asphalt Pyrolytic Characteristics and Kinetic Analysis

Thermogravimetry experiments and thermal analysis kinetics are used to analyze the effects of magnesium hydroxide on asphalt pyrolysis characteristics. The pyrolysis models are developed based on experiments to evaluate the flame-retarded mechanism of magnesium hydroxide to asphalt. The results indicate that asphalt pyrolysis process in N2 is a single stage, and presents unimodal character in DTG curves. Owing to endothermic decomposition and crystal water release of magnesium hydroxide, the temperature rise of asphalt is inhibited. Pyrolysis of SBS modified asphalt follows a one-dimensional pyrolysis mechanism model, but flame-retarded SBS modified asphalt follows a three-dimensional pyrolysis mechanism model. After adding magnesium hydroxide, asphalt pyrolysis kinetics parameters are raised and become available to decrease reactive activity and rate. Based on this study, it is obvious that the thermal stability of asphalt is improved by magnesium hydroxide under high temperatures. Equally, the flame-retarded performance of asphalt is also enhanced by using magnesium hydroxide.