Effect of water-to-binder ratio on the properties of CSA cement-based grouting materials with LiAl-LDH

The compressive strength of sulfoaluminate cement-based grouting materials (CBGMs) cannot meet the requirement of repair and reinforcement engineering in the presence of high water-to-binder ratio (w/b) of 0.5-1.2. Using nanotechnology, the mechanical property of the CBGM paste at different ages can be improved and our previous experimental results showed that lithium aluminum layered double hydroxides (LiAl-LDHs) with nanostructure can significantly increase the compressive strength of CBGM paste. In addition to the characteristics of nanomaterials, the performance of nanomaterials is also related to w/b of paste. In this work, the effect of w/b ratio on the compressive strength, hydration process, and products of calcium sulphoaluminate cement (CSA) CBGMs with and without LiAl-LDH was studied. Results indicate that with the increase of w/b from 0.6 to 1.0, the growth rate of compressive strength of CBGM paste with LiAl-LDH enhanced. Moreover, LiAl-LDH enhanced total hydration heat more effectively at a higher w/b and as the w/b increased from 0.6 to 1.0, the growth rate of hydration product boosted, which is the reason why the enhancement ratio of compressive strength of the paste was larger at high w/b.