Effect of Combined ASR and Cyclic Loading on Concrete Bridges

Reinforced concrete beams were subjected to the combination of mechanical loading and alkali-silica reaction (ASR) in order to investigate the durability of concrete under their combined action. This experiment used locally-sourced materials such as aggregates and admixtures in order to develop a concrete mix that will give the optimum resistance to such combined action. Half of the specimens were subjected to static, and cyclic loading and exposure to accelerated ASR-inducing environment and the other half were exposed only to an ASR-inducing environment. The test results indicate that the expansion due to the combined action was significantly different from that in specimens exposed only to a high-alkaline environment. The micro and macro cracks induced by cyclic loading form paths leading to an increased ASR rate, while the macro-mechanical cracks provide regions of relatively free expansion, as can be deduced from the decreasing crack widths.