To elucidate the relationship between compressive strength and pore structure of the high water grouting material with different water-binder ratios and CaO contents, the compressive strength was tested while pore structure including pore characteristic parameters and pore diameter distribution were investigated by BET, MIP, and 3D-XRM. Moreover, the evolution of hydration products was observed by TGA and SEM, illustrating the reactive mechanism of the material. Furthermore, the grey correlation coefficients between compressive strength and pore structure parameters were illustrated according to the grey correlation theory. The results show that CaO content in lime is proportional to the compressive strength with the water-binder ratio of 1.0 or 1.5, while the inverse trend appears with the water-binder ratio of 2.0. The high water grouting material belongs to the macropore material with the pores mainly within 100 nm to 2 μm. Its hydration products contain ettringite crystals, aluminum gels, and C-S-H gels. The productions of the hydration products are positively correlated with its compressive strength. In addition, the compressive strength of the high water grouting material is closely related to the pore characteristic parameters and the pore size distribution, especially the porosity, the most probable pore diameter, and the pore volumes within 100~500 nm and 10~100 nm.

https://www.mdpi.com/2073-4352/11/8/865/pdf

The Relationship between Compressive Strength and Pore Structure of the High Water Grouting Material

Based on laboratory experiments, the paper researches the effect of polyvinyl alcohol (PVA) content on the performance of fly ash-based cement grouting materials. The test results show that the addition of PVA has limited effect on the initial and final setting time and brings a certain but minor delay on the appearance of the hydration peak period. It enhances cement hydration during the hydration slow down period. The impermeability of PVA to the grouting material is obviously improved, and it increases with the growing amount of PVA content. PVA improves the flexural strength and compressive strength of the sample block to varying degrees, and the improvement on flexural strength is more obvious than that on the compressive strength. It has a significant effect on the mechanical properties of the grouting material and can effectively improve the rock mass’s hydraulic coupling characteristics. It also has great application value and practical significance for the prevention and control of water hazards in deep coal stopes.

/pdf/experimental-study-on-the-influence-of-pva-content-on-the-1zx3unc9m7.pdf

Experimental Study on the Influence of PVA Content on the Performance of Grouting Material in Deep Stope

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.

https://iopscience.iop.org/article/10.1088/1757-899X/439/4/042047/pdf

Linli Yu

Papers

Study on mechanical properties and microstructure of the new grouting material