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    二氧化碳矿化养护加气混凝土试验研究

    Investigation on CO_2 mineralization curing of aerated concretes

    • 摘要: 本文主要对基于工业固废的加气混凝土的二氧化碳养护技术进行了初步探索,着重研究了原料掺比、养护压力以及养护制度在CO2 矿化反应中的影响。通过SEM 和XRD 分析等方法表征了在不同养护工况下反应产物的变化特点,同时也使用压汞法测定了CO2 养护前后的孔隙分布。结果表明,对自然养护4d 后的加气混凝土进行2 小时CO2 养护,试件固碳率随着养护压力升高而升高,低压养护和梯级养护有利于降低加气混凝土试件的力学强度损失,梯级养护中CO2 浓度/分压力越高,加气混凝土试件表观固碳率越高;在相同的CO2 养护条件下,SEM 观察到矿化反应产物有不同的形貌,如球状和纺锤形等,XRD 的分析则进一步证明了碳酸钙有三种不同晶型;CO2 养护之后,孔径在0.01-0.1μm 范围内的微孔降低明显,表观固碳率越高,对加气混凝土试件的填充效果越显著。

       

      Abstract: CO_2 mineralization curing concrete technology makes concrete rapid forming and improve mechanical properties in a short time,greatly shorten the curing cycle,improve production efficiency,is a large-scale industrial application prospect of carbon dioxide utilization. In this paper,the CO_2 curing of aerated concrete based on industrial solid waste raw materials was mainly studied,and the effects of raw material ratio,curing pressure and curing method on the CO_2 mineralization reaction were mainly studied. The formula of carbon dioxide curing aerated concrete is mainly determined by the compressive strength and carbon fixation performance of the specimen. The change characteristics of the reaction products under different curing conditions were characterized by SEM and XRD,and the pore distribution before and after CO_2 curing was measured by mercury intrusion method. The results show that the carbon fixation ratio of the specimens increases with the increase of the curing pressure when the aerated concrete after natural curing for 4 days is cured for 2 hours. Low pressure curing and stepped curing are beneficial to reduce the mechanical strength loss of the specimens. The higher the CO_2 concentration/partial pressure of the second stage of cascade curing is,the higher the apparent carbon fixation rate of the specimens is; Under the same CO_2 curing condition,SEM observes that the products of mineralization reaction has different morphology,such as spherical and spindle shape,XRD analysis shows that there are three different crystal forms of calcium carbonate; after CO_2 curing,the micropores with pore diameter in the range of 0.01-0.10 μm decrease significantly,and the higher the apparent carbon fixation ratio is,the more significant the filling effect on the aerated concrete is.

       

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