Abstract

Info

Title:: Temperature Effects of Wet Shotcrete and Optimization of Fiber Content During Cold Period

Author(s):: WU Ai-xiang; YU Shao-feng; WANG Yi-ming; School of Civil and Resource Engineering, University of Science and Technology Beijing

Keywords:: wet shotcrete support; low temperature; fiber content; SEM; RDP test

Abstract:: In order to solve the problem of poor effect of wet shotcrete support of Jinying gold mine during cold period, the factors affecting its performance were analyzed, and it was considered that low temperature and unreasonable fiber ratio were the main problems. The strength tests and surface characteristics scanning electron microscope (SEM) analysis of concrete specimens were carried out under curing temperature 0, 6, 13, 20 ℃, respectively, and the above analysis was explained by the hydration reaction of concrete. Based on RDP experiment, the loaddeflectionenergy curves of different types of concrete disc specimens with different contents of synthetic fibers were analyzed, and the fibers which could meet the requirement of underground roadway support of the mine was optimized. According to the experiments of temperature influence and the results of RDP experiment, the applied research was carried out on the spot. The results show that the rebound rate of concrete after wet shotcrete is obviously reduced when the underground temperature is controlled above 10 ℃ and the C fiber (6 kg·m^-3) is added to concrete. The operation time of roadway access is greatly shortened, and the uniaxial compressive strength of wet shotcrete can reach 30 MPa. The method can fully meet the support requirements of Jinying gold mine.