Influência das condições de exposição na autocicatrização de argamassas com adição cristalizante fissuradas mecanicamente

Abstract

Cracking in cementitious materials is a recurring pathological issue that reduces durability by facilitating the ingress of aggressive agents. As a sustainable alternative since it reduces the need for repairs and extends structural service life this study aimed to analyze the behavior of mortars containing a crystalline admixture regarding the efficacy of enhanced autogenous self-healing in mechanically induced cracks. The methodology was exploratory and experimental in nature, involving material characterization and the development of mortar mixes with a 1:3:0.5 ratio, using CP-V-ARI Portland cement, IPT-standardized sand, and crystalline admixture dosages of 1% and 2%. Prismatic specimens (4x4x16 cm) were cast and, after 14 days of curing, subjected to mechanical flexural cracking to produce crack widths between 0.1 mm and 0.3 mm. Crack closure was monitored weekly via optical microscopy; concurrently, water absorption and mechanical strength tests were conducted, comparing submerged conditions against intermittent wetting-drying cycles. Results in the fresh state indicated a reduction in fluidity proportional to the increase in crystalline admixture content. In the hardened state, mechanical properties specifically flexural tensile strength and compressive strength were not compromised; in fact, strength gains were observed with the addition of the crystalline agent. Microscopic analysis confirmed complete crack closure, with submerged conditions proving more efficient than exposure to wetting-drying cycles. It was concluded that the incorporation of the chemical agent promoted enhanced autogenous self-healing through the precipitation of crystals that filled the cracks. From both technical and economic perspectives, the 1% dosage proved to be the most advantageous, as it yielded performance similar to the 2% dosage while using less admixture, thereby making its application more cost-effective.