Abstract
Waste concrete powder (WCP) is proposed to replace part of the cement to seek environmentally friendly grouting materials for ground improvement in mine goaf. The optimal mixing proportion was selected based on the performance indexes of the water-separation ratio, stone rate, viscosity, setting time, and compressive strength. X-ray diffraction (XRD) and scanning electron microscopy (SEM) tests were also conducted to analyze mineralogical phases and investigate the microscopic mechanism. Test results show that the slurry prepared by the substitution rate of 70% and adding 0.05% water-reducing agent meets well the requirements of ground grouting in mine goaf. The WCP produced by grinding mainly exerts microaggregate effect in the slurry due to low activity. A lot of pores on the surface of WCP were shown by SEM which can absorb the water in the slurry and increase the stone rate. The WCP application for ground grouting in mine goaf can not only recycle WC but also provide new grouting materials for goaf ground.
Highlights
China’s mineral resources are rich and widely distributed
It can be seen that the water-separation ratio of the slurry gradually decreased and the stone rate gradually increased as the replacement rate increased, indicating that the mixing of waste concrete powder (WCP) can make the slurry more stable and the filling effect for ground in mine goaf better. is is due to a large amount of water absorbed by the pores on the surface of WCP particles, reducing the water-separation ratio and increasing the stone rate of the slurry
In order to use waste concrete powder (WCP) in grouting for ground improvement in mine goaf site, WCP-Cement slurry with replacing 50%–90% of cement is proposed and studied. e influence factors of setting time, fluidity, water-separation ratio, stone rate, and compressive strength were studied, and an environmentally friendly slurry suitable for ground treatment in mine goaf is optimized by adding water-reducing agent later
Summary
China’s mineral resources are rich and widely distributed. Large areas of goafs have been formed with the continuous exploitation of mineral resources. Serious geological disasters are often caused by the instability of goaf, which threatens the safety of human life and property and breaks the original ecological balance of nature [1, 2]. With the rapid economic development and the in-depth advancement of urbanization, urban land resources are becoming increasingly tight, and engineering construction on the goaf site has become an inevitable trend [4]. Research and treatment of the ground in mine goaf are an essential prerequisite for such activities. Grouting technology is widely used in the field of geotechnical engineering and disaster prevention
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