Effect of different water-cement ratios on the durability of prefabricated concrete tanks exposed to acetic acid aggression

Abstract

In this paper a study of the mechanisms of the destructive effect of acid on concrete tanks used on farms is presented. It analyzed the extent and type of damage that occurred and demonstrated the possibility of preliminary detection of the problem also using unusual test methods such as surface morphology tests and SEM microstructural analysis. The experiment focused on exposing 10% acetic acid to cubic samples of ordinary concrete of different W/C ratios. Samples were immersed in acetic acid for 270 days. The compressive strength and mass loss were then determined, and the surface morphology was analyzed with roughness parameters measurements. They showed that compressive strength of the samples stored in acetic acid was in the range of 38–51% decrease in comparison to the control samples. The best results were obtained for concrete samples of W/C ratio = 0.45. Concretes with a W/C ratio higher than 0.5 were less resistant to acetic acid. The results also allowed discussion of the phenomenon of destructive processes occurring in the concrete structure as a result of acetic acid, making the effects of these actions depending on its W/C. SEM microstructural analysis confirmed that the destruction mechanism is based on reactions of acetic acid with portlandite and C–S–H phase and leaching calcium ions.