Researches On Carbonation Of Concrete With Multi-mineral Admixtures

It is singnificant to study carbonation of concrete with multi-mineral admixtures, not only to improve the durability of mineral admixture concrete structures under atmospheric environment,but also to forecast the life of concrete structures,which is the basis of durability of concrete structures with mineral admixtures under the combined effect of carbonation and other factors(freeze-thaw,chloride ion etc.).In this paper,one important parameters of the theoretical model of carbonation m₀ which is the amount of the CO₂ absorbed by per cubic meter of full carbonation concrete is discussed based on cement hydration,the second hydration process of mineral admixtures,and mechanism of concrete carbonation.Then a formula is proposed for the calculation with the main parameters of amount of mineral admixture,and the impacts of different admixtures on m₀ is analysed.Papadakis advanced a formula for calculating the CO₂ effective diffusion coefficient,based on which a formula regarding concrete with multi-mineral admixtures is derived.And a multi-mineral admixture mixed concrete carbonation depth prediction model is suggested.Rapid carbonation test of complex mixture of mineral-doped concrete is carried out,and the influence of the water-cement ratio,mineral admixture content, the type of admixture and the ratio of admixtures on the depth of carbonation of concrete are analysed.And the results of the carbonation test are used to verify the theoretical model established in this paper.