Experimental Study On Forced Carbonation Of Cement Concrete

As one of the basic materials,cement has a wide range of applications in many fields such as water conservancy,transportation,and construction.In the process of producing cement,a large amount of energy is consumed and a large amount of CO₂ is discharged.With the growing threat to humanity from greenhouse gases,we are faced In the process of producing cement,we need to consume a lot of energy,and emit a lot of CO₂,and the greenhouse gas is becoming more and more dangerous to people,so it is urgent to save energy and reduce emission.Cement base material mineralization CO₂ fixation is one of the important way to achieve efficient use of cement,not only can solve the problem of energy conservation and emissions reduction of CO₂,with high strength cement concrete products,can also be prepared to provide strong support for the green development of construction industry,realize the sustainable development of cement industry.Therefore this study put forward the concrete effective geological mining CO₂ fixation,on the one hand,need to understand the influence of cement hydration and the optimum process conditions of reaction of carbonate and rule,on the other hand through mineralization means to enhance the strength of the concrete block.The main research contents and achievements are:The mineralization of cement concrete to fix CO₂ is an important way to achieve efficient use of cement.?1?Study on the carbonization reaction characteristics of the cement slurry:according to the on-line observation of water mud body pH,the cement hydration reaction rate is relatively fast,and80%of the hydration reaction can be completed in 10-20 seconds;The influence of hydration temperature,stirring speed and concentration on pH value of cement hydration slurry was limited.Generally,temperature change has little effect on cement hydration reaction.The mixing speed is accelerated,and the cement hydration will be accelerated to a certain extent.The cement slurry concentration?solid liquid ratio?increased,and the pH value of slurry is increased to a certain extent.The carbonation temperature and CO₂ flow have a great influence on the cement carbonation reaction.CO₂ flow increased,cement carbonation reaction rate increased,but the reaction rate of CO₂ in the cement carbonation reaction decreased.By the test before and after the reaction of carbonate cement raw material and product thermo-gravimetric curve,which can effectively draw cement mineralization ability of carbon sequestration,under this experimental condition of cement carbon mineralization rate is about 3.5%,that is every tons of cement can be mineralized CO₂ fixation about 35 kg of cement with a certain solid carbon reduction potential,and has great practical value.?2?Study on carbon fixation CO₂ reaction characteristics of cement concrete products.Both cement and cement concrete test blocks have the effect of mineralization to fix CO₂,which can be used to reduce the amount of CO₂.The strength of the test block can be effectively increased by the carbonization maintenance of cement concrete test block,and the increase of the test block is up to 85%,which shows a good prospect of industrialization application.The thermal decomposition temperature is high after the carbonization treatment of the cement paste and its concrete test block,and the formation and adhesion mechanism of the cement paste should be further studied.?3?Study on the mechanism of cement concrete mineralization to fix CO₂.Through the analysis of different means of XRD,XRF,SEM,EDS,proves the real means can CO₂ fixation on the one hand.On the other hand,it can improve the strength of concrete block.The following conclusion can be got:carbonate cement,CO₂ fixation,mainly by the hydration products of cement hydrate react with CO₂.Under different carbonized curing conditions,different morphology of calcium carbonate crystals can be produced,such as hexagonal,tufted,fibrous,etc.,to enhance the strength of concrete test blocks.