1. Professor, Changsha Univ. of Science and Technology, Chiling Rd. 45#, Changsha, Hunan 410076, People’s Republic of China; and, Texas Dept. of Transportation, 4203 Bull Creek #39, Austin, TX 78731 (corresponding author).
2. Division Head, Materials and Pavements Div., Texas Transportation Institute, 501 CE/TTI Building, Texas A&M Univ., College Station, TX 77843.