Grouts Incorporating Supplementary Cementitious Materials for Two-Stage Concrete

Two-stage concrete (TSC), also known as preplaced aggregate concrete, is produced through placing coarse aggregate particles in the formwork and subsequently injecting grout to fill the interparticle voids. The ability of the used grout to flow around the preplaced aggregate particles and effectively fill voids has a predominant effect on the TSC properties. Due to the unique formulation of TSC grouts, rheological studies on other common cementitious grouts do not readily apply to TSC grouts. In particular, the effects of different supplementary cementitious materials (SCMs) on the properties of TSC grout mixtures remain largely unexplored. Therefore, in the present study fresh and hardened properties of grout mixtures incorporating various SCMs, including fly ash (FA), silica fume (SF), and metakaolin (MK), were investigated. Results indicate that a water-to-binder ratio (w/b) = 0.45 was suitable to achieve the recommended grout flowability for successful TSC production. Moreover, TSC grout properties highly depended on the type and dosage of SCM used. The findings of this study should stimulate further research and novel applications of TSC, considering that the TSC technology has remained so far basic and needs to accommodate recent advancements in cement-based materials.