Mechanistic-Empirical Design Concepts for Continuously Reinforced Concrete Pavements in Illinois

The Illinois Department of Transportation (IDOT) currently has an existing jointed plain concrete pavement \n(JPCP) design based on mechanistic-empirical (M-E) principles. However, their continuously reinforced concrete \npavement (CRCP) design procedure is empirical and based on a modified AASHTO nomograph for jointed \nreinforced concrete pavement. The objective of this study was to develop and implement an M-E design \nprocedure that IDOT could use for routine CRCP design. The proposed procedure is based on mechanisticempirical \ndesign principles taken largely from the models presented in NCHRP 1-37A and on work completed by \nDr. Dan Zollinger of Texas A&M University. The equations for calculating the mean crack spacing and the \nnumber of punchouts per mile at the end of the design life for a given traffic volume, pavement layer and CRC \nslab geometry, shoulder type, and layer material properties have been implemented in a user-friendly \nspreadsheet. Several new developments in the proposed design process are fatigue damage accumulations at \nthe critical top and bottom location in the CRCP slab, equations for calculating the equivalent damage ratio for \nseveral shoulder types and crack stiffness values, application of a strength reduction factor to the concrete \nstress ratio calculated at the surface of the CRCP, and a new logistic-type punchout prediction model. Due to \nthe numerous measured and assumed input variables in this CRCP design framework, the mechanistic analysis \nwas calibrated against CRCP field performance data from Illinois and CRCP accelerated pavement test data \ncompleted at the University of Illinois.