Early-age performance of longitudinal bridge joints made with shrinkage-compensating cement concrete

Longitudinal joints that connect adjacent box beams in bridges are known to experience early-age cracks due to temperature and shrinkage effects. Such cracks can open a direct path for water and deleterious agents to penetrate into the bridge, causing corrosion of embedded steel rebars and degradation of superstructure and substructure elements. To mitigate this problem, a solution explored in this study is to use Type K shrinkage-compensating cement, which has the promise to enhance the volume stability of concrete, minimize early-age cracks, and thus, increase the service life of the entire structure. For achieving a holistic assessment of this solution, a test setup consisting of two full-scale box beams connected with concrete made with Type K shrinkage-compensating cement was investigated in the laboratory setting under various temperature profiles. Response data, including temperature, longitudinal and transverse strain/stress, and deflection, were collected at the joint and each box beam during the thermal tests. To extend the scope of investigations beyond the temperature profiles tested in the laboratory, a set of three-dimensional finite-element simulations were performed as well. The results obtained from both experimental tests and numerical analyses showed that the stresses in the joint made with shrinkage-compensating cement concrete remain below the cracking threshold under temperature and shrinkage effects. With maintaining a proper bond with the box beams, the developed joint was found to provide superior performance, especially at early age, addressing the issues associated with the use of conventional concrete in longitudinal bridge joints.