Investigation of cracks in mortars containing mineral additives qwing to alkali-silica reaction using image processing techniques

Alkali-silica reaction (ASR) is an important process that occurs between alkalis in cement and reactive silica in aggregates and negatively affects the strength and durability of concrete and reinforced concrete structures due to the expansion resulting from the reaction. This process causes an increase in internal stresses, which manifest themselves as cracks. In this study, the effect of mineral additives on ASR-induced cracks was investigated by image processing techniques. Within this scope, crack images were obtained from mortars containing different proportions of fly ash (FA), blast furnace slag (BFS), silica fume (SF), and metakaolin (MK), and the expansions of the mortar samples were measured. Additionally, the relationship between the average crack width measured from the mortar surface and the expansion percentages was analyzed comparatively using image processing techniques. Significant decreases in expansion values were observed in mineral-added mortar samples compared to the reference sample at 3, 7, 14, and 28 days. The results obtained from image processing techniques showed that there were significant decreases in ASR-induced crack widths with an increase in the mineral additive percentage. The greatest reduction in crack width was observed in mortar samples containing 60% YFC, while the smallest reduction was observed in mortar samples containing 5% SF. Except for the results obtained on mortar samples containing silica fume, there is a statistically significant relationship between the average crack width and expansion measured for all mineral-added mortar samples. Key Words: Alkali-Silica Reaction, Mineral Additive, Image Processing, Crack Width