Durability of glass fiber/vinyl ester composites as bridge deck subject to weathering conditions

The deterioration and functional deficiency of existing bridge infrastructure represent one of most significant challenges currently facing civil engineering community. Due to the unique combinations of high specific strength and stiffness, ease of construction, corrosive resistance and reduced maintenance costs, the FRP bridge deck systems are considered to be favorable substitutes for the deteriorating bridge decks. Since the applications of FRP composites for bridge deck under consideration all involve the exposure of the composite to moisture and thermal cycle, it is critical that a mechanistic understanding of materials response be developed at the fundamental level while simultaneously allowing for the development of models not just for the prediction of property changes with time but also for determination of remaining service life of a structure.; This research presents results of an investigation into the durability of E-glass/Vinyl ester composites exposed to a series of controlled environments in an attempt to understand the primary mechanisms and rates of degradation, prior to considering complex regimes such as of indeterminate changes in humidity, temperature cycles, and exposure to other solvents, as would be expected in the field. First, this research presents development of a durability testing procedure for FRP composites bridge deck materials. This procedure has considered the unique characteristics of the intended application, including materials property variations, mechanical loading, and freeze/thaw cycling in water and salt water. Then, results from laminate theory analysis and extensive testing on laminates as a function of freeze-thaw cycle and moisture are presented which provide insight into how material properties vary with freeze-thaw cycle and moisture and form the inputs necessary to evaluate composite strength and damage models.; To allow for sufficiently generalized descriptions of life, credible simulations that accurately describe the combination of synergism of load and environment must be used to ensure practical and efficient design guidelines for durability. A two-step finite element computation approach was used to perform mathematical modeling and analysis of the entire complex FRP composite bridge superstructures. The durability composite materials models are combined with finite element analysis to yield a general analysis procedure for predicting the long-term deformation and residual strength response of FRP sandwich deck subjected to environmental exposure. The durability finite element model predictions are compared with the laboratory testing and in-field testing results, giving good agreement.