Study on the preparation and properties of high-belite cementitious materials from shield slag and calcium carbide slag

Abstract

With the continuous increase in subway construction in China, a large amount of shield slag is produced. The piling and transportation of shield slag seriously affect the urban environment. Therefore, it is necessary to study the recycling technology of shield muck to reduce its environmental pollution and realize its resource utilization. Jinan shield muck contains a large amount of calcareous muck and clayey muck. It is feasible to prepare silica-aluminum cementitious materials through the reasonable combination of these mucks. In this study, calcareous slag and clayey slag were used as the main raw materials, and calcium carbide slag, iron powder, silica fume and alum soil were used as correction materials to prepare high-belite cementitious materials based on the residue. By measuring the content of free calcium oxide and using X-ray fluorescence diffraction, scanning electron microscopy and differential thermal analysis, the formation mechanism of high-belite cementified materials under different doping conditions was studied. The results show that the addition of CaSO4 and CF2 can significantly improve the burnability of raw materials when the saturation coefficient of lime holding time has a great influence on the formation of clinker. According to the Rietveld quantitative phase analysis, under the doping state, the content of belite can reach more than 50%. The content of this mineral can effectively overcome the problem of the low short-term strength of high belite cementite materials. Through the above research, it was confirmed that the shield mule of Jinan metro can form high-belite cementitious material.