Performance of concrete in highway bridges: A field study of highway bridges

An investigation undertaken to relate durability and concrete quality was described in this report. A comparison of the quality parameters of concrete of different ages was also made. The concrete structures were all bridges, built between 1915 and 1972. Their durability was defined primarily by the ability of the concrete to protect the steel reinforcement from corrosion, as evidenced by spalling. A visual survey was made of over 100 bridges in three areas of winter severity. From this broad survey 17 bridges of varying ages and exposure conditions were chosen. From each of these bridges 1-6 areas of sound or failing concrete were selected for detailed study. Six core samples were taken from each area, and the quality of the concrete assessed by a variety of tests ( water absorption, oxygen permeability, strength, chloride, cement and gas content, density, carbonation, water-cement ratio). The durability of the concrete in each case was assessed as sound or failed. The quality of modern concrete was found to be superior to older concrete, and the depth of cover over the reinforcement was greater. All material parameters measured were found to be related to durability, but an attempt to find correlation between the different parameters of the samples taken from the bridges was not successful.