MARTINSBURG WV -- Supported by the West Virginia Division of Highways (WVDOH), a team from West Virginia University (WVU) led by Dr. Indrajit Ray and Dr. Julio F. Davalos had undertaken a state-wide and large-scale research program on development, evaluation, and implementation of advanced materials program for bridge decks of the state. The execution of this program is planned on close collaborations with the industry, Contractors Associations of West Virginia, and Builders Supply Association of West Virginia as members of the project's advisory panel. The ultimate goal is to develop performance -based specifications of High-Performance Concrete (HPC) and Specialized Concrete Overlays for the state of West Virginia. A comprehensive laboratory scale study including development of optimum HPC and its fresh, hardened, cracking, durability, and permeability properties evaluations is complete. A number of mixtures have been developed using West Virginia sources of aggregates and local materials. The research project is now producing and evaluating test slabs to qualify lab mixtures at different locations in the state of West Virginia with the help and collaborations of ready mix concrete plants. In consistent with FHWA and other states, the proposed HPC using local materials will have very low chloride permeability, low shrinkage and cracking, high resistant against freezing and thawing with low life-cycle cost. Finally, based on the plant scale study, full-scale bridge projects will be undertaken by WVU in the future. Potomac Construction Industry (PCI) of Martinsburg was selected as one of the state plants in collaboration with WVU team led by Dr. Ray and Dr. Davalos to construct and evaluate HPC test slabs in the Eastern Panhandle using local aggregates and construction procedures. Based on the HPC mix developed in WVU lab and subsequently verified by PCI, two types of HPC such as fly ash+ silica fume and slag+ silica fume, respectively were used to construct slabs. The concrete were supplied by PCI ready mix concrete plant and the entire construction procedure simulated the real bridge deck construction methods starting from mixing, transporting, pouring, vibrating, consolidation, finishing, and curing. Fig. 1 displays the deck slabs and field specimens ready for pouring and Fig. 2 shows discharge of HPC from truck.

The slabs were instrumented with maturity loggers/thermocouples to record maturity/temperature continuously up to 90 days. This data will be used to develop strength-maturity relationships for of HPC which will be useful for the implementation of HPC by the state. The HPC collected at the point of discharge was monitored under both field and laboratory curing conditions. The parameters measured were: compressive strengths at 1, 3, 7, 14, 28, 56, and 90 days; the freezing and thawing cycles, rapid chloride permeability, and shrinkage. The vibratory strain gages were attached with data acquisition system to monitor early age and long term shrinkage at every minute up to 90 days. Fig. 3 shows the finishing of slabs using vibratory screed and bullfloating (Fig. 3) and molding of field specimens is shown in Fig. 4.

Finished slabs and field specimens are shown in Fig. 5. A continuous moist curing were followed using wet burlap and plastic sheet covered to ensure durable HPC (Fig. 6).

Core samples will be collected from the slabs at 28-day, 56-day, and 90-day to measure compressive strengths, rapid chloride permeability, air-void parameter, and petrography for quality control of finished slabs and long-term performance of the HPC. Soon, the findings will be used for full scale HPC bridge deck implementation including development of first performance-based HPC specs for WVDOH.

More images from the test slabs can be found here.