Experimental Study On Temperature Rise Control Of Calcium Silicate Slag Concrete

For the safety of concrete structures,the hydration heat release of cementitious materials is always an important factor that cannot be ignored.In terms of reducing the temperature rise of concrete,adding mineral admixtures can be regarded as an effective means.Research on the mineral admixtures to reduce the temperature rise of concrete mainly focuses on the materials such as fly ash,silica fume and slag,and there is a lack of exploration and research on new mineral admixtures.Calcium silicon slag is the industrial solid waste produced by the extraction of alumina from high alumina coal ash.Excessive accumulation will occupy a large amount of land and cause significant damage to the natural environment.The harmless treatment of calcium silicon slag has always been an environmental protection problem to be solved urgently.The calcium silicate slag contains a large amount ofβ-C₂S,the content of which is about 90%,which is close to the mineral composition of cement clinker,and has the characteristics of slow hydration heat release and low hydration heat release.Using calcium silicate slag as solid waste admixture,cement calcium silicate slag composite system can not only reduce the hydration heat of cementitious materials and control the temperature rise of concrete,but also deal with calcium silicate slag in large quantities,realize zero discharge of calcium silicate slag,reduce land occupation and protect the environment.In this paper,silica-calcium slag is used as the test material,age and content are used as the test parameters to carry out hydration heat,concrete adiabatic temperature rise,chemically bound water,XRD,TG-DSC and SEM experimental research,through silica-calcium slag-cement composite The comparison between the system and the pure cement paste is to study the regulation law of silica-calcium slag on the adiabatic temperature rise of concrete and its influence on the hydration process of the composite system.Through the research,it is found that adding calcium silicate slag into cement according to a certain amount,on the one hand,it can effectively reduce the total hydration heat of the composite system,and at the same time,it can significantly reduce the temperature rise of concrete;on the other hand,it can delay the appearance of hydration heat release peak,and reduce the peak temperature rise rate of concrete.As the content of calcium silicate slag increases,the temperature rise and temperature rise rate of concrete show an obvious downward trend.The temperature rise curves of pure cement concrete and three groups of calcium silicate slag concrete have basically the same trend,indicating that calcium silicate slag can be very good.Regulate the temperature rise of concrete.The hydration process of the calcium silicate slag-cement composite system is not greatly affected by the low content of calcium silicate slag,and even has a certain promotion effect on the hydration rate and the degree of hydration.The rate of hydration,the degree of hydration,and the products of hydration all have a greater impact.The hydration heat and chemical bound water decrease gradually with the increase of calcium silicon slag content,and the increasing trend tends to be flat after 7d age.Through the analysis of XRD,TG-DSC and SEM test results,as the content of calcium silicate slag increases,the amount of hydration products gradually decreases,and the microstructure is more dense.