The Theoretical And Experimental Study Of Supercritical Carbon Dioxide On Transforming Cement-base Building Materials

Cement-base material in civil engineering has extensive application. Theycommonly are concrete and cement concrete slab watts, and regeneration of brick andso on these components contain cement building material. They are the most widelyused because of its good waterproof, easy machining, easily acquired and economyetc. But the performance of building materials requires for the improvement with thedevelopment of human material life and this let cement-base material put forwardhigher request, such as high strength, high permeability, good waterproof propertiesand so on, so the reforming concrete cement base building materials also appears to beespecially important. On the other hand, cement industry manufacturing activity willemissions of CO2to the atmosphere. In recent years the global temperature rise alongwith a large number of industrial activity of human, a large amount of carbon dioxideemissions is thought to be the main cause for the greenhouse effect.This paper studied supercritical carbon dioxide of reforming concrete buildingmaterials using carbonation depth and performance change in order to develop therecovering of carbon dioxide. First the main understanding and the conclusion athome and abroad for the carbonation of cement-base material were summarized;mechanism of concrete carbonation, including the mechanism of natural carbonationand supercritical carbonization were analysed, the factors of various influencingsupercritical carbonation was discussed and three parameters influencing carbonationdepth were determined. They are carbonization time, the density of carbon dioxideand the strength of the cement base material; porous materials coupling closeddifferential equations according to A.Saetta literature were established.A set of supercritical carbon dioxide equipment handling cement-base materialwas independently designed and adopted according to the idea of foreign equipment,experiments of concrete and cement and other cement base material were studied.This is the main innovation points of the paper. Experiments was given focus on thecarbonation depth and strength changes. It also analyzes the parameter of influencingcarbonation depth.The supercritical carbonation of concrete using coupling finite element analysissoftware Comsol was numerically simulated and was verified the effectiveness of thenumerical model before fitting the test results. The concrete carbonation depthcalculation formula of supercritical carbonization was given according the form ofNiuDi formula; and according to test data, the added value of the compressivestrength of concrete was fitted to forecast the strength of concrete after supercriticalcarbonation; the formula of absorbing carbon dioxide by three type of concrete that isdisposed medium density supercritical carbon dioxide and this is helpful to forecast concrete compressive strength and the weight of the absorbing carbon dioxide in theapplication process.