Combination of immersion and semi-immersion tests to evaluate concretes manufactured with sulfate-resisting cements

Abstract

Usually the regulation defines the concentration of sulfates to consider aggressive soil or water. There are different standards to evaluate the resistance of concretes to the external sulfate attack. Most of these tests are based on the immersion of samples in solutions with high concentration of sulfates. But in the field, the concretes are also exposed to wet–dry cycles and the crystallization of salts can occur. In this work, 65 concretes manufactured with sulfate-resisting cements are tested. The cores were tested during 1 year submerged in sodium and calcium solutions for analyzing aspect, expansion, and variation of weight. After this, the cores were exposed to the same solutions semi-immersed for 2.5 years. After being semi-submerged for 1 year, some of the concretes revealed/showed alterations. After 2.5 years, around 15% of cores showed cracks and loss of material, due to formation of ettringite and thaumasite.