Latex and Microsilica Modified Concrete Bridge Deck Overlays in Oregon

摘要

The final report presents information collected by ODOT personnel from bridgedeck overlays constructed in Oregon between 1989 and 1995. Decks were placed on a variety of existing bridge types prepared using hydrodemolition, milling, and diamond grinding follwed by sand, water or air blasting. Both latex and microsilic overlays were placed under a variety of environmental conditions. The study investigated causal relationships between construction and environmental factors and deck cracking and delamination and, where warranted, recommends procedures to minimize these distresses. Statistical analyses of available environmental and construction information from several overlays constructed between 1989 and 1993 failed to clearly establish the cause(s) of delamination or cracking. Petrographic studies of cores taken from these decks appear to show increased microcracking in substrates prepared with milling compared to those prepared with hydrodemolition. Diamond ground substrates were not included in this phase of the study. This analysis supports increased use of hydrodemolition over milling. In an effort to establish the casual relationships, detailed environmental and material property data were collected during construction on five bridges in 1995. Statistical analyses of data provides information on the range of environmental conditions under which bridge deck may be placed, however, little cracking or delamination was noted in any of the five bridges. Thus, the cause(s) were not identified.