Abstract

Currently, TxDOT uses the AASHTO 93 design guide for the slab thickness design of continuously
reinforced concrete pavement (CRCP). The AASHTO 93 design guide was developed based on the AASHTO road test, where JCP (jointed plain concrete pavement) was the major pavement evaluated and CRCP was not included. From a purely technical standpoint, the AASHTO 93 design guide is not appropriate for the design of CRCP. With ever-increasing traffic on major highways in Texas where CRCP is widely used, there is a need for a more mechanistic-empirical (ME) based pavement design procedure for CRCP. An ME-based pavement design method will allow TxDOT to optimize pavement structures to best utilize the limited financial resources available. To develop an ME based CRCP design procedure, the mechanism of punchouts was identified by field evaluations of CRCP, which included coring, deflection testing using falling weight deflectometer (FWD), and other nondestructive testing. Once the punchout mechanism was identified, mechanistic modeling was performed using a 3-dimensional finite element program. Another important element in the ME based pavement design procedures is the accuracy of a transfer function. A transfer function was developed using the data from TxDOT PMIS. A CRCP design program based on ME principles was developed, called TxCRCP-ME, with a User's Guide for the program. In the program, the effect of nonuniformity of subbase support, or the effect of erosion, was not directly addressed. From a theoretical standpoint, the effect is included in a transfer function. Sensitivity analysis was conducted to evaluate the effects of input variables and the reasonableness of the results. Since the reasonableness of TxCRCP-ME depends on the accuracy of transfer function, further efforts are recommended to refine the transfer function by collecting more accurate information on traffic, construction information and distress data. Once an accurate transfer function is developed, further sensitivity analysis will be needed to evaluate the reasonableness of the TxCRCP-ME. For the spalling issue, extensive field evaluations were conducted for the performance of spalling. A spalling model was developed and calibrated with field evaluation data.