Perpetual Pavements in Texas: The Fort Worth SH 114 Project in Wise County (0-4822-2)

The work contained in this interim report provides a case study describing the design, construction, initial structural evaluation, and performance predictions of the full-depth perpetual pavement constructed on SH 114 in the Fort Worth District. Based on the research findings, recommended improvements to design and construction practices are proposed. The research methodology and scope of work included data collection, laboratory and field testing, computational simulations, and performance predictions. Laboratory testing for characterizing the asphalt mixture properties included the Hamburg, the Overlay Tester, Dynamic Modulus, and Repeated Load Permanent Deformation tests. Asphalt-binder testing was accomplished with the Troxler Ignition Oven and the Dynamic Shear Rheometer, respectively. Field testing involved visual surveys, coring, infra-red quality control tests, forensic investigations, and non-destructive performance evaluations using Ground Penetrating Radar (GPR) and Falling Weight Deflectometer (FWD) measurements. Computational analyses included the FPS, PerRoad, VESYS, and MEPDG software. The SH 114 design utilized the perpetual pavement concepts, with a thick l-inch stone-filled layer as the main structural component. This layer was found to be considerably stiffer than the traditional TXDOT mixes. However, this material was also found to be highly permeable and subject to vertical segregation. During construction, the Fort Worth District found it necessary to retrofit edged rains to minimize problems with water trapped in the asphalt layers. For comparison purposes, the Fort Worth District also included a similar section constructed with traditional dense graded mixes. Laboratory and field results from both sections are included in this report. Recommendations are also provided for the structural design of future perpetual pavements in Texas. From the results presented in this project, the current designs are very conservative. The results generated support the transition to higher design moduli for these full-depth pavements.