1. Ph.D. Candidate, Dept. of Civil, Construction and Environmental Engineering, Iowa State Univ., 427 Town Engineering Bldg., Ames, IA 50011 (corresponding author).
2. Project Manager, National Concrete Pavement Technology Center, Iowa State Univ., 2711 South Loop 4700, Ames, IA 50010.
3. Professor and Head, Dept. of Civil and Environmental Engineering, Oklahoma State Univ., 207 Engineering South, Stillwater, OK 74078.