Influence of temperature and aggressive solutions in the formation of thaumasite and ettringite in standard and commercial mortars

Formation of thaumasite or ettringite is depending on the temperature and the presence of carbonates, apart from the sulphate concentration. Although in the field exposition, these conditions may vary during the service life. In addition, not always is possible to control the composition of the commercial mortars or concretes. In the present work, seven different mortars are studied under two temperatures and three external solutions. The temperatures are 5 ºC and 20 °C. The solutions are water, sodium sulphate and sodium sulphate plus calcium carbonate. The aggregates are calcareous in the commercial mortars, and calcium carbonate, quartz and opal plus quartz in the standard mortars. The aspect, expansion and weight variation are analysed with time. The mortars with alkali reactive aggregates (opal plus quartz) show alteration under all conditions with variable damage. On the other hand, the expansion and the formation of thaumasite or ettringite is favored by low temperature and solution combination.Peer reviewe