Effect of self-healing in closing cracks from the sulfate attack in Portland, supersulfated and alkali-activated cement

Efeito da autocicatrização no fechamento de fissuras decorrentes do ataque por sulfato em cimento Portland, supersulfatado e álcali ativado

Abstract

Self-healing consists of closing cracks and recovering the watertight properties of cement-based materials and can occur by hydration of the materials of the mixture (autogenous) or by materials added to the mixture for this purpose (autonomous). This study consists of the use of stimulated self-healing as a way of mitigating sulfate attack (sodium and magnesium), with the evaluation of the influence of crystalline admixture in this process. For that, cycles of sulfate attack and self-healing (by wetting and drying cycles in water) were performed, aiming to evaluate the behavior of mortars with three types of cement: Portland, supersulfated, and alkali-activated. The results showed that self-healing was not sufficient to close cracks due to sulfate attack. This behavior was associated with the hypothesis that the high calcium content of the crystalline admixture reacted with the sulfates and formed expansive products, increasing the attack rate.

Keywords:
Sulfate attack; Portland cement; Supersulfated cement; Alkali-activated cement; Self-healing; Crystalline admixture