Tentative application of expansive cementitious materials in grouting-A systematic review

Traditional grouting reinforcement has been well reported only to provide a bonding effect to a jointed rock mass. Nowadays, the expansive grout technology has been touted as an alternative to provide squeezing reinforcement effects to a jointed rock mass. Still in infancy, there is a lack of state-of-knowledge on its fundamentals and applications to enhance stability in the surrounding rock. This review article aims to define, characterize, and summarize the mechanism and behavior of cement/concrete expansion additives, cement foaming additives, and high soundless cracking agents (HSCA). Further, this review discussed the characterization of the expansion behavior of cementitious materials, and highlighted the potential applications of expansive grout in grouting reinforcements. This review is focused on determining the optimum selection of suitable expansive materials needed for expansive grout to improve its reinforcement efficiency, in addition to examining technical studies on the expansion mechanism and behavior of distinct expansive cementitious materials. The expansive cementitious materials were analyzed based on four mechanical criteria in grouting and concrete structures: volume expansion ratio, expansion development time, uniaxial compressive strength, and expansion stress. This overview is expected to enrich the current knowledge of expansive cementitious materials and aid researchers in advancing its applications in future global grouting reinforcement projects in jointed rock mass and steeply inclined layered rock mass support systems.