Accelerated external sulfate attack: Improved laboratory methods, considering physical and chemical processes

Abstract

The most common and well‐known method for evaluating the sulfate resistance of cement blends is ASTM C1012 procedure. It takes at least 12–18 months to evaluate the results, considering this standard. The present research proposes two supplementary methods to accelerate the sulfate ions penetration into the mortar bars used in ASTM C1012. Both of these two supplementary methods were evaluated by studying mortar samples' expansion, mass change, visual condition, compressive strength, ultrasonic pulse velocity, and XRD. In the first method, a developed device provided an electrical conduction environment for mortar bars made of three cement blends. The results showed that this method produced between 8 and 16 times more expansion considering different studied cement blends. In the second method, mortar bars of seven cement blends were exposed to a devised prior condition under vacuum. Considering the results, this method produced between 2.5 and 9 times more expansion in relation to each cement blend and approach. Additionally, an excellent polynomial correlation was observed between the expansion of new accelerated methods and ASTM C1012 results. It can be concluded that using these accelerated methods as complementary to ASTM C1012 can help to evaluate the sulfate resistance of cement blends in a shorter time period.