Study on the influence mechanism of activated coal gangue powder on the properties of filling body

Abstract

Coal gangue is a common solid waste which largely produced during coal mining, and its large discharge has caused great pollution and damage to the environment. The objective of this paper is to improve the resource utilization rate of coal gangue, and study the influence mechanism of activated coal gangue powder (CGP) on the working performance, mechanical properties and water resistance of Coal Gangue-based Green Cemented Filling Body (CGGCFB) through macro and micro experiments. The results indicate the following: (1) The properties of CGGGCFB can be significantly improved by adding an appropriate activated CGP content. (2) Considering the economy, it is suggested that the replacement rate of activated CGP should be between 50%∼75%. (3) The micro-morphology effect and micro aggregate effect of activated CGP weaken the “micro-pump water absorption”, “water storage” and surface particle friction of coal gangue aggregate, so that it has strong hydrophilicity, water fixation and water retention, thus the working performance is improved. (4) The pozzolanic effect and micro-aggregate filling effect of activated CGP not only increase the number and types of hydration products and bond energy in the filling body, make a large number of pores tend to be “spherical” or “arch” stress characteristics and enhance the stress characteristics of internal pores, but also restrain the extension of the original micro-cracks formed by the “material attribute defects” of coal gangue, thereby resulting in improvement of filling body strength and water resistance greatly. The research results of this paper can further improve the resource utilization rate of coal gangue resources, give full play to its advantages of regionalization and resource utilization, and provide theoretical reference for the research and application of coal gangue in mine filling.