Synergistic effect of surfactant and chlorine salt on dispersion of nano-SiO2 and performance of cement-based grout containing a large amount of bentonite

Influence of premixed chlorine salt on the pore characteristics of cement-based hardened grout containing a large amount of bentonite

“…Application scope of some pore structure test methods [16,17]. 12 In this paper, the pore structure of hardened grout was classified into two major categories (gel 13 pores and capillary pores) with a pore size of 10 nm as the dividing line (as shown by the red dashed 14 line in Fig. 1).…”

“…Nevertheless, the large incorporation of bentonite (reaches about 50%) reduces the workability of fresh slurry due to the strong water absorption of montmorillonite, which is the main component of bentonite, and decreases the mechanical properties of hardened grout because of the reduction in cement content [2]. Thus, in our previous study, nano-SiO2 (NS) and accelerator (chlorine salts such as NaCl and CaCl2) were added to the material to improve the weakened mechanical properties [3].…”

“…Chlorine salt, as one of the most widely used accelerators, was added to improve the performance 27 of cement-based grouts containing a large amount of bentonite in our previous mixture design [3]. 28 Chlorine salt can accelerate the hydration or reaction of the cement or supplementary cementitious materials and quickly enhance the early strength [9,10].…”

“…The early strengthening effect is mainly attributed to the reaction between chloride ions and tricalcium aluminate (C3A), which calls chloride binding and finally forms Friedel's salt [11]. When NaCl is introduced into the cement-based material, it will firstly react with Ca(OH)2 and then react with C3A, as shown in Eqs ( 1) and (2), respectively [12]. While for CaCl2, it will directly react with C3A shown in Eq.…”

Study on the effect of nanosilica suspension on the properties of cement-based grouts

“…Senff et al [17] presented that the addition of nanosilica in cement mortar may reduce the flow table spread from 230 mm down to 207 mm, owing to the obvious increase of the viscosity of paste. Hence, some researchers suggested that the appropriate amount of nanosilica particles added in cement-based materials should be in the range of 1-5 wt% [18]. Additionally, the property had been strongly dependent on the dispersion state of nanosilica particles.…”