Evaluation of restraint method and seawater resistance of reinforced concrete with expansive additive

Abstract

Reinforced concrete with expansive additive introduces shrinkage-compensated strain under the constrained conditions of the reinforcement, which reduces cracking and improves durability. However, there is not a few methods for evaluating the performance of concrete with expansive additive in restraints, and there is not enough data available. Therefore, this paper proposes a method for evaluating the durability of reinforced concrete with expansive additive by Cage-shaped restraining steel bars with four longitudinal steels and stirrups installed at both ends. Furthermore, to investigate seawater resistance, a three-year exposure test was conducted in an environment simulating the submerged zone, tidal and splash zone.

As a result, the use of restraining steel bars has made it possible to numerically evaluate the expansion and contraction behavior of concrete with expansive additive. The behavior of concrete with expansive additive was confirmed under exposure conditions. Under the exposure environment, the submerged zone showed expansion behavior and the tidal and splash zone showed shrinkage behavior. The pore structure of concrete with expansive additive depended on the exposure conditions, although densification occurred in reinforcing steel bar restraints. The chloride ion penetration depth of concrete with expansive additive in a marine environment under restraining conditions was almost the same as that of concrete without expansive additive. The seawater resistance of concrete with expansive additive is not considered to be particularly poor, judging from the distribution of concentrations of the major elements.