Macroscopic and microscopic trans-scale characteristics of pore structure of mine grouting materials
(1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China;
2. Nanyang Centre for Underground Space, School of Civil and Environmental Engineering, Nanyang Technological University, Singapore)
2. Nanyang Centre for Underground Space, School of Civil and Environmental Engineering, Nanyang Technological University, Singapore)
Abstract: The pore structure and porosity of three kinds of mine grouting materials were characterized based on a thin-section analysis and low-field nuclear magnetic resonance (NMR) technique. The macroscopic pore interconnectivity was investigated using binary images captured from thin sections and a random walk pore spectral dimension (RWPSD) algorithm. The experimental results show that the microstructure of the grouting materials used consisted of interlayer pores, gel pores, capillary pores, circular air holes, and small fractures, and tailings can fill some gaps in the hydration product structure and dense hydration products. There is a positive correlation between pore interconnectivity and curing time. In addition, there is a relationship between pore interconnectivity and porosity. With increasing porosity and pore interconnectivity, a non-uniform pore structure occurs in mine grouting materials with an accelerator and results in reduced setting time and later strength.
Key words: grouting material; pore microstructure; pore interconnectivity; trans-scale study; nuclear magnetic resonance; thin-section analysis; random walk pore spectral dimension