Life-Cycle Performance of Concrete Bridge Decks Exposed to Deicer Environments: A New Risk Rating Method

摘要

One way to assess the life-cycle performance of bridge decks is to use risk rating factors. Risk rating factors tend to increase with time, as a bridge deck ages and deteriorates. The major influential factors of bridge deck deterioration in cold climates include materials characteristics, construction quality, freeze/thaw cycles, deicer exposure, and overload trucks. Unlike laboratory testing where all test samples are subjected to similar environmental conditions, the concrete samples cored from bridge decks experienced much more complicated conditions. As such, it is a challenge to evaluate the field conditions of concrete structures, pavements and bridge decks through the analysis of their core samples. An assessment tool to facilitate the condition assessment of concrete bridge deck using a limited number of core samples is useful for bridge owners to implement preservation, repair and rehabilitation strategies in a timely fashion. In this study, the maintenance history and gas permeability and strength testing results from limited core samples were analyzed using a simplistic empirical-mechanistic model. The model was developed to assess the current condition of bridge decks exposed to deicer environments. This was made possible by coupling the percolation theory with the power law for strength and permeability. Specifically, the model accommodated input parameters of freeze/thaw cycles, average daily traffic (ADT), average annual deicer usage, and engineering properties measured from deck core samples (e.g., splitting tensile strength and gas permeability coefficient). Microscopic characterization through scanning electron microscopy (SEM) confirmed the validity of the new tool, as it better captured internal damage in concrete decks that showed little signs of surface distress.