A Study on Cement-Based Crack Injection Materials Using Reactive Ultra-Fine Fly Ash, Portland Cement (Type I), and Sulfoaluminate Cement

The primary objective of this study is to determine appropriate mixes for cement-based crack injection materials by combining Portland cement (type I) and sulfoaluminate cement (SAC) with reactive ultra-fine fly ash (RUFA). Various weight percentages of SAC (WSAC) and Portland cement (type I) (WC) as binder materials were considered, while the weight percentage of RUFA (WRUFA) in the binder was fixed at 5%. The usage of RUFA enhances the fluidity and strength of the paste, while SAC helps to mitigate shrinkage and improve early strength. The results indicate that the mixture with a water-to-binder ratio of 0.4, WSAC = 75%, WC = 20%, and WRUFA = 5% can meet the requirements of relevant standards in terms of injectability, average splitting tensile strength, bleeding rate, and volume change. In addition, this mixture provides optimal performance in terms of setting time, compressive strength, slanted shear strength, and length change.