The Experimental Study And Mechanism Analysis Of Coal Cinder Used As Cement Admixture

In2013, the total output of cement in China has reached24.1tons, the total output of clinker has reached more than13.6tons,account for more than50%of the world. The raw materials of cement are limestone and clay, which both are non-renewable resources, increasingly scarce. Cement production process consumes large amounts of energy and emissions a large amount of CO2and dust, intensifying the greenhouse effect and haze weather. At the same time, along with the development of the industrialization process, industrial waste production amount is huge, occupying the land, causing environmental pollution every year. If the industrial waste is used as cement mixing material to replace partial cement, will kill two birds with one stone. In recent years, the use of industrial solid waste for building materials is environmental protection and energy saving technology supported by government, ordinary Portland cement, fly ash cement and slag cement, ash cement, etc., plays a more and more important role in cement production. Fly ash, in particular, has been widely used in the field of building materials, has a tendency to demand.Coal cinder is a industrial waste boiler, which is prodused in thermal power plant, the annual generating volume is huge, more than100million tons. At present, the utilizationrate of coal cinder is very low, few were used for the preparation of brick and paveing the way, the rest were piled, resulting in environmental pollution and resource waste. Coal cinder and fly ash are of the same origin, chemical composition and mineral are very similar,which provides the possibility of the application of coal cinder used in cement production. At present, the related research of coal cinder used as cement admixture is less, the actual production has not formed the industrialization, the main reason is that coal cinder’s early activity is low, resulting coal cinder content is low, so it can not form a large number of consumption of coal cinder. In view of the above question, the author studied on the basic physical, chemical properties of coal cinder in this paper, adopted physical and chemical methods to stimulate coal cinder’s activity, increased the content of coal cinder gradually from multi clinker, low clinker to no clinker to study the feasibility of coal cinder used as cement mixed material.The main work and research results are as follows:(1) Under the condition of multiple clinker, use mechanical activation means to stimulate the activity of coal cinder. Study the influence of the grinding time, and coal cinder content on the fineness, mortar strength, normal consistency, setting time, soundness, etc, and to determine the best and largest of coal cinder and the optimal dosage of grinding time.(2) Under the condition of low clinker,study the influence of coal cinder and cement content on cement strength, to determine the optimal formula of compound cement. Considering the early strength of compound cement is low, stimulate the activity of coal cinder with physical and chemical methods, study the different kinds of excitation agent through single mixing, mixed with excitation effect of scoal cinder activity. Studies have shown that the effect of the two kinds of exciting agent is better than that of only mixing, effect of lime-sulfate type mixed optimal.(3) Under the condition of no clinker, using lime soda phase to stimulate the activity of coal cinder and slag, under standard curing conditions, study the changes in the strength of the cement mortar. Considering the early strength of cement is almost zero, post strength grows slowly. Using the autoclave curing conditions, accelerate the condensation hardening process of cement, as a result, the strength of mortar15MPa, even more than20MPa.(4) Using electron probe microscopic test, X-ray diffraction (XRD) and scanning electron microscopy (sem) technology, analyzes the net slurry and cement hydration products of coal cinder chemical composition, mineral composition and particle morphology, analysis of the mechanism of coal cinder hydration provides theory basis for the preparation of cement mixed material...