Sulfate attack of Portland cement concrete under dynamic flexural loading: A coupling function

In saline regions, infrastructures (e.g., structures under earthquake, pavement slabs, bridge decks, airfield runways, railway sleepers and railway bridges, even high-speed railways and concrete structures in ocean) are attacked by sulfate compounds (Na2SO4, MgSO4, etc.), coupled with dynamic loading. This report studied the flexural strength, relative dynamic elastic modulus and sulfate content under sulfate attack incorporating with dynamic flexural loading (stress level = 20%, 40% and 60%), and also analyzed the microstructure and atom ratio of attached samples via SEM and EDS. The result shows that solution concentration and stress level are two primary and important factors in sulfate attack cases. Meanwhile, opposite with the static attack case, dynamic loading will also make the strength loss occur earlier, especially under high stress level of dynamic loading (60%). The reinforcement contributed by new phase forming on flexural strength is offset because of the additional dynamic loading. Additionally, the experimental result revealed that the relative dynamic elastic modulus can be used to semi-quantitatively evaluate the long-term sulfate attack samples, but is not suggested to be used on short-term sulfate attacked samples because the result does not match the flexural strength trend. Based on the updated data in this study, sulfate attack stages coupled with dynamic flexural loading are summarized.