Study On The Powder Of Metamorphic Slate Waste For Partly Replacing Of Cement

Recently, with the rapid development of our national economy, the cement industry has been developing dramatically with its cement production ranking first in the world. However, the increasing growth of cement has put great stress on the natural resources and environment because the technology of our cement industry is rather falling behind. Among all these environmental problems, the air pollution by the emission of CO₂ is the most serious one. According to statistics, the production of per ton of cement will cause nearly one ton of CO₂ discharge, which means an astonishingly big amount of CO₂ coming out of cement factories. As the environmental pollution arising therefrom has attracted more and more attention, all nations are urging for reduction of CO₂ emission.The research and application of such admixture as fly ash provide people with a new approach to replacing cement with admixture and thus reducing CO₂ emission. China is one of the biggest production countries of slate, where most of the slate production bases are producing slate out of metamorphite mines. During that process, so many wastes are brought about that it doubtlessly will be both environment-friendly and economical to utilize these wastes as admixture replacing cement partially.This thesis is to measure the chemical components of stone with X-ray fluorescence method and to measure the grain-size distribution of stone dust by means of centrifugal grading analytic instrument. Strength test, fluidity test and drying shrinkage test are conducted at different ratios of replacement. The feasibility of replacing cement with slate waste is evaluated from the four aspects of strength, working performance, shrinkage and economical performances. The biggest ratio of replacement is obtained as a result. It is also studied how grain-size and chemical components of slate waste relate to strength, working performance and shrinkage performances of cement mortar. At the same time, the microstructure of cement mortar mixed with slate waste powder is researched on using SEM.It is shown that the strength, working, shrinkage and economical performances of cement mortar mixed with wasted stone dust of metamorphite are as good as expected and valuable both environmentally and economically, so that it can partially replace cement as green and environmentally protecting material for sustainable development.