Evaluation and Selection of Sealants and Fillers Using Principal Component Analysis for Cracks in Asphalt Concrete Pavements

The objective of this paper was to develop a comprehensive evaluation method and index to evaluate the performance of sealants and fillers for cracks in asphalt concrete pavements using the method of principal component analysis. The performance experiments including cone penetration, softening point, flow, resilience and tension at low temperature respectively were conducted by reference of ASTM D5329 for eight sealants and fillers often used in China. There by a principal component model was developed and weight of every index was calculated. The experimental results show that there are significantly different performances for sealants and fillers often used in China. Principal component analysis is an objective method that evaluates and selects the performance of sealants and fillers for cracks in asphalt concrete pavements.

Microstructure Morphologies of Asphalt Binders using Atomic Force Microscopy

We investigated microstructure morphologies of three asphalts（SK, Karamay, and Esso） used in China using atomic force microscopy（AFM）. The topography and phase contrast images were obtained. Topographic profile and three dimensional images were described. Roughnesses of microstructure were calculated. And the chemical compositions of asphalt were tested to explain the microstructural mechanism of the asphalt. The results show that the topography and phase image in atomic force microscopy are appropriate to evaluate the microstructure of the asphalt binder. There are significant differences in microstructural morphologies including bee-like structure, topographic profile, 3D image, and roughness for three asphalts in this study. There are three different phases in microstructure of asphalt binder. The oil source and chemical composition of asphalt, especially asphaltenes content have a great influence on the microstructure.

A hybrid strategy in selecting diverse combinations of innovative sustainable materials for asphalt pavements

This project integrates recent innovations of recycled materials used in designing and building sustainable pavements. An increasing environmental awareness and the demand for improving economic and construction efficiencies, through measures such as con- struction warrantees and goals to reduce air pollution under the Kyoto Protocol, have increased the efforts to implement sustainable materials in roadways. The objective of this research is to develop a systematic approach toward selecting optimum combinations of sustainable materials for the construction of asphalt pavements. The selected materials, warm mix asphalt （WMA）, recycled asphalt shingles {RAS）I and reclaimed asphalt pave- ment {RAP） were incorporated in this study. The results of this research are intended to serve as guidelines in the selection of the mixed sustainable materials for asphalt pave- ments. The approach developed from this project draws upon previous research efforts integrating graphical modeling with optimizing the amount of sustainable materials based on the performance. With regard to moisture susceptibility and rutting potential test re- suits, as well as the MIM analysis based on a 95% confidence interval, the rutting perfor- mance and moisture susceptibility of asphalt mixtures are not significantly different regardless of the percentages of RAS, RAP, or WMA. The optimum mixture choices could be made by the plant emission rankings with consideration of the optimal WMA types, per- centages of RAS/RAP, and WMA production temperatures. The WMA mixtures prepared with 75% RAP and Advera WMA have produced the lowest CO2 emissions among the investigated mixture types.