An Experimental Study to Investigate the Effect of Concrete Crack Dimensions on the Effectiveness of SIKADUR 31-CF SLOW in Concrete Repair Works

Abstract

This study aimed to evaluate the effect of concrete crack dimensions (width and depth) on the repair efficiency of Sikadur 31-CF Slow by comparing flexural strength before and after repair and calculating mechanical recovery percentages. The results confirmed that variations in crack dimensions play a pivotal role in determining the material's effectiveness. The uncracked reference samples exhibited a flexural strength of 3.85 MPa, which was adopted as the standard value for comparison. When repairing cracks with a narrow width (1 mm) and a moderate depth (5 cm), the recovery rate reached 95%, while it decreased slightly to 92.63% as the depth increased to 7 cm, reflecting the effect of depth on reducing efficiency despite a constant width. The widest (5 mm) and deepest (7 cm) cracks recorded the lowest repair efficiency at 35.67%, indicating that increasing both width and depth simultaneously doubles the loss of mechanical properties after repair. It was also found that small, shallow cracks (1 mm x 2 cm) in the tensile strength test achieved recovery rates exceeding the reference (104.37%), which may be attributed to improved cohesion of the repaired layer and more homogeneous stress distribution. Conversely, increasing crack dimensions led to a significant decrease in recovery rates, in some cases falling below 60% of the original strength. These results confirm that controlling crack dimensions is a key factor in ensuring the optimal performance of Sikadur 31-CF Slow. Controlling natural cracks means treating them as soon as they occur, before they worsen, to limit their development and maintain the structural integrity of the concrete element. Treatment materials generally demonstrate greater efficiency in repairing small cracks compared to large ones. Therefore, optimal repair strategies should aim to reduce crack width and depth to the limits that allow for the highest levels of mechanical strength recovery in the concrete.