Study on mechanical properties and microstructure of the new grouting material

Abstract

The new grouting material with advantages of early strength, strong liquidity, better expansibility and environmental protection can be applied to underground structure engineering. The effects of different w/b ratios, curing ages, limes and SiO2 on the compressive strength of the new grouting material were investigated. By SEM and TGA-DSC analysis, its microscopic morphology and hydration products are explored. The results show that the early strength of the new grouting material develops rapidly, and the 3d compressive strength can reach 80% of the 28d compressive strength. Under the condition that the w/b ratio is 1.0, the compressive strength increases with CaO content in lime increasing. The addition of micron-SiO2 can improve compressive strength by about 5% when the formulation is reasonable. The main hydration products of SEM-EDS are needle-like ettringite, spherical aluminum gel and amorphous C-S-H(C-A-S-H) gel, corresponding to three endothermic peaks appearing in TGA-DSC at around 90°C, 230°C and 660 °C, respectively.