Cracking in Concrete Bridge Decks

Abstract

The causes of cracking in concrete bridge decks are investigated, and procedures are recommended to alleviate the problem. Forty continuous steel girder bridges, thirty-seven composite and three noncomposite, from northeast Kansas (KDOT District I) are evaluated. Field surveys conducted to document cracking patterns and to determine the crack density of each bridge are described. Information collected from construction documents, field books, and weather data logs is presented and compared to the observed levels of cracking to identify correlations between cracking and the variables studied. Thirty-one variables are considered. These include material properties, site conditions, construction procedures, and design specifications, as well as age and traffic volume. Based on the research reported herein, cracking in monolithic bridge decks increases with increasing values of concrete slump, percent volume of water and cement, water content, cement content, and compressive strength, and decreasing values of air content (especially below 6.0% ). Bridge deck overlays placed with zero slump concrete exhibit consistently high levels of cracking. Cracking in overlays also increases as placement lengths increase. High maximum air temperatures and large changes in air temperature on the day of casting aggravate cracking in monolithic bridge decks. High average air temperatures and large changes in air temperature similarly aggravate cracking in bridge deck overlays. Both monolithic and two-layer bridges with fixed-ended girders exhibit increased cracking near the abutments compared to those with pin-ended girders.