Dominant Role of Cement Paste Content on Bridge Deck Cracking

Abstract

The cracking of concrete bridge decks is a nationwide problem. The results of over 100 crack surveys on 40 monolithic composite concrete bridge deck placements supported by steel girders were used to evaluate the factors contributing to bridge deck cracking and determine the factors that have the greatest influence. The parameters considered were the material properties, such as paste content (volume of cement and water), slump, compressive strength, and air content, and environmental factors, such as air temperature range, high air temperature, and time of placement on the day of construction. Results showed that, within the ranges studied, paste content has a dominant effect on cracking, with cracking increasing substantially when the volume of paste exceeds a threshold value of 26.4% of concrete volume while being insensitive to changes in paste content below this threshold. Bridge decks placed and finished between midnight and noon exhibited substantially lower cracking than those placed and finished between early morning and late night. Other factors such as slump, compressive strength, and air content affected cracking to a limited degree, with a higher slump, greater compressive strength, and lower air content, resulting in slightly higher cracking, effects that are not statistically significant.