Effect of polyvinyl alcohol/aluminum microcapsule expansion agent on porosity and strength of cement-based drilling sealing material

摘要

In the process of gas drainage, the cement-based expansion sealing material with excellent permeability can effectively seal the cracks in the roadway pressure relief zone and the broken drilled area. However, expansion material has low strength and poor compactness. Therefore, the authors use microcapsule technology to modify the expansion agent to make the material expand after reaching sufficient strength, weaken the influence on the material structure and pores, achieve the coordinated development of expansion and performance, and improve the efficiency of gas drainage. In the paper, the uniaxial compression experiment and NMR experiment combined with the fractal dimension and material volume change is used to quantitatively analyze the influence of delayed expansion on the mechanical strength, porosity and pore connectivity of the sealing material. Experimental data proves the feasibility of applying microcapsule technology. The results show that the slope of the curve between the expansion rate and peak stress, porosity of ordinary expansion materials is 0.9931 and 0.0672, which is greater than 0.8925 and 0.0563 of microcapsule expansion materials. Microcapsule material has high strength, low porosity, and better sealing effect. Besides, the proportion of adsorption holes in the microcapsule material increases, and the seepage holes decrease.(c) 2021 Published by Elsevier Ltd.