Research On Early Carbonation Of Mineral Admixture Concrete

Compared with the traditional concrete,the process of mineral admixture concrete carbonation show a huge difference,especially the early carbonation speed of mineral admixture concrete is very fast.The traditional calculation model of concrete carbonation depth was set up based on the analysis of the carbonation process of Portland cement concrete,it is not suitable for the prediction of mineral admixture concrete carbonation depth,there is a big deviation when it is used to predict the early carbonation depth of mineral admixture concrete particularly.Because the early carbonation speed of mineral admixture concrete is very fast;rebound method,that it is widely used for the acceptance inspection of engineering structure,is revised according to the carbonation depth of concrete,and the resulting rebound strength is often lower than the actual strength of concrete,which greatly limits the widespread use of rebound method in the engineering structure.Early carbonation problem of mineral admixture concrete has aroused many scholars’ attention,but the early carbonation mechanism for mineral admixture concrete,the early carbonation law and the main influencing factors,the calculation model of early carbonation depth,the influence of early carbonation on the durability of concrete structure are still not clear.Systematic research on early carbonation of mineral admixture concrete will provide reliable theoretical support for the durability design and assessment of mineral admixture concrete structure,and lay the foundation for the good implementation of our country’s sustainable development strategy.This paper selects fly ash,slag powder,coal gangue as admixture;through the carbonation test of the concrete or mortar mixed with mineral admixture under natural exposure environment,the development law of mineral admixture concrete carbonation in 360 d after pouring was studied,and the influence of curing time,type and content of admixture on the development of concrete strength and carbonation were analyzed systematically.On the basis of the analysis for the influence of concrete carbonation depth by the type and content of admixture,the influence coefficient of mineral admixture on carbonation speed was put forward;and combined with the analysis of other factors affecting the carbonation depth of mineral admixture concrete,the calculation model for early carbonation depth of mineral admixture concrete was established.Using the contrastive study of phenolphthalein reagent test,p H value test and chemical composition analysis,the early carbonation mechanism of mineral admixture concrete and the change law of material composition in the concrete during the early carbonation process were analyzed.And with permeability test,the effect of early carbonation on anti-erosion ability of mineral admixture concrete was studied.