Early-Age Behavior of Internally Cured Concrete Bridge Deck under Environmental Loading

The early-age cracking of bridge decks is a typical issue in the US that reduces service life. Internally cured (IC) concrete has been used in some states to reduce or eliminate the development of cracks in reinforced concrete decks. However, limited research has been conducted to evaluate the field performance of internally cured concrete bridge decks. This paper presents the field behavior of an IC concrete deck and an adjacent conventional concrete (CC) deck during their early age. Strain gauges and thermocouples were installed at several locations along the bridge length to measure the concrete and reinforcement strains and the temperature in both bridges. The results indicated that the majority of shrinkage occurred during the first week after the concrete placement. However, the deck with the IC concrete experienced less longitudinal and transverse strains when compared with the conventional concrete deck. The largest reduction in longitudinal and transverse strains of the IC concrete deck were 64% when compared to the CC concrete deck. The lower strains led to a reduction of early age cracks. Furthermore, it was noted that the rise of hydration temperature in the CC deck was higher than that of the IC concrete deck. However, the IC concrete deck remained warmer over time. Also, the contribution of reinforcement at the early age was investigated. It was observed that the reinforcement reduced the tensile strain in the concrete deck generated due to shrinkage. The largest reduction in longitudinal strain at the top and bottom of the IC concrete deck was 65% compared to the free shrinkage strain.