A Preliminary Mechanistic Evaluation of PCC Cross-Sections using ISLAB2000-A Parametric Study
Principal Investigator:	Neeraj Buch, Michigan State University
Co-Principal Investigator:	Thomas Van Dam, Michigan Technological University
Research Assistants:	Kaenvit Vongchusiri
Funding Agency:	Michigan Department of Transportation
Period:	Two Years, on-going

The 1986/1993 AASHTO guide is based on the serviceability concept, which is most highly correlated to pavement ride quality. This empirical approach does not necessarily assure structural integrity, nor does it directly account for the effects of pavement type (JPCP versus JRCP), joint spacing (including widened lanes), variation in material properties along a project, environmental impact, and joint design (aggregate interlock versus dowel bars) on pavement design. Further, it does not effectively address the impact of the heavy, multi-axle "Michigan Truck" on the performance rigid pavements.\

Realizing that the only way to address the multiple factors influencing rigid pavement performance is through a more mechanistic approach, MDOT and MnDOT jointly funded a study to enhance the ILLISLAB 2-D FEM rigid pavement analysis program. ILLISLAB is widely recognized as the most versatile state-of-the-practice rigid pavement analysis software available. The enhancement entailed the complete rewriting of the code to remove inefficiencies, significantly improving the computational ability of the software. It also included the employment of a graphical user interface (GUI) both for inputting data and examining the output. A working version of the enhanced software, called ISLAB2000, is now under evaluation. The use of ISLAB2000 allows the user to assess the impact of rigid pavement design and construction variables on pavement response to temperature and loading. In combination with established transfer functions, ISLAB2000 provides a means to address many of the shortcomings inherent in the 1986/1993 AASHTO procedures, resulting in improved design practices for rigid pavements in Michigan.

1. To evaluate the ISLAB2000 software and provide feedback to the software developers.
2. Perform a parametric study on current and anticipated MDOT rigid pavement cross-sections, using design inputs consistent with Michigan loading, climatic, materials, subgrade support, and construction parameters. The parametric study will result in a family of pavement responses (stresses and deflections). The limitation is that ISLAB2000 does not predict pavement performance.
3. To prepare and conduct technology transfer workshop(s) for MDOT pavement designers to familiar them with the ISLAB2000 program.