A Study on the Pre-Hardened Shrinkage Reduction of Grout Using Carbon Materials

In this study, the characteristics of grout mixed with charcoal as an expansive agent were examined to reduce the pre-hardening shrinkage of cementitious materials. This study compared and reviewed the application of CSA, a conventional expansive agent, to grout. The setting time, fluidity, compressive strength, and pre-hardening shrinkage/expansion were evaluated to explore the usability of charcoal as an expansive agent. The test results confirmed that, as the incorporation rate of charcoal increased, the pre-hardening expansion rate of the grout also increased, making it more effective for pre-hardening expansion than the conventional expansive agent CSA. However, when charcoal was used as an expansive agent, the compressive strength decreased after hardening, indicating the need for caution regarding the amount of charcoal used. Furthermore, the pre-hardening shrinkage and expansion rates of the various types of charcoal used in this study showed some differences, suggesting the need for further research on the internal pore volume and pore size of the charcoal.