Influence of cement type on resistance to organic acids

Resistance to attack by acids is an important characteristic in a number of concrete applications. Deterioration can occur by three mechanisms: acidolysis, complexolysis and precipitation of expansive reaction products. Generally, where acidolysis is the main mechanism, a low-calcium cement is likely to impart enhanced resistance. However, where other mechanisms may also be effective, the approach to selecting cements for acid resistance is less clear. This paper examines the effect of four acids on cement pastes made from three different cement types using measurements of mass loss, chemical and mineralogical analysis and micro computed tomography scanning. In addition, geochemical modelling techniques are employed to explore further the role that salt precipitation and complexolysis are likely to play.