Lab-scale reproduction test method for temperature-driven movement of through-thickness cracks in concrete exterior walls for crack repair evaluation

Abstract

Crack repair is an important process for extending the service life of buildings. Crack movement is one of the factors that affect the durability of crack repair; however, there is no existing method to evaluate the repair under the influence of crack movement. To this end, this paper proposes a lab-scale crack movement reproduction test method to evaluate the effectiveness and durability of the repair. The movement of cracks penetrating the thickness of the concrete wall (through-thickness cracks) was monitored on both the indoor and outdoor sides. The results showed that the through-thickness cracks produced a bending-like movement with movement amplitudes of about 0.03 to 0.08 mm, driven by indoor and outdoor temperature differences; the resulting deterioration pattern in the repair area was a combined outcome of temperature and mechanical loading. The reproduction experimental method was established in reference to numerical simulation. Experimental results verified that the proposed test method satisfies the relationship between movement amplitude and the temperature difference, restraining force, and initial crack width in actual buildings. In addition, the method is stable, with a coefficient of variation of 7.73% in the movement amplitude for ten experimental groups. Furthermore, it was suggested that reducing the temperature gradient in the wall cross-section can reduce the deterioration caused by crack movement.