Effect of cement content on the performance of static cracking agent

Conventional blasting for rock and concrete demolition in sensitive environments inevitably generates adverse effects such as excessive noise, vibration, and flying rocks. To avoid these problems, static cracking agents (SCAs) provide a safer and more practical alternative by fracturing rock or concrete through the substantial volumetric expansion associated with the hydration of CaO to Ca(OH)2. However, conventional SCA suffers from inherent drawbacks, including relatively rapid hydration reaction rates and unstable expansion performance. To address these limitations, this study focuses on regulating the hydration reaction process and expansion performance of SCA by adjusting the proportion of cementitious materials in their composition. The experimental results show that a cement content of 12% provides the optimal expansion performance, with a volumetric expansion ratio of approximately 600%. Meanwhile, the hydration reaction is effectively moderated, and the peak temperature occurs at approximately 15 min. The mixture containing 10% cement exhibited the earliest crack initiation and the highest average crack-width development rate of 4.50 mm/min, whereas the mixture containing 12% cement achieved the highest volumetric expansion ratio and an average crack-width development rate of 2.35 mm/min. In summary, compared with conventional SCAs, adjusting the proportion of cementitious materials enables effective control over the hydration reaction rate and expansion performance of SCAs. This research provides valuable theoretical support for the design and application of high-performance SCA in rock and concrete demolition under complex engineering conditions.