二氧化碳矿化养护加气混凝土试验研究

二氧化碳矿化养护混凝土技术使得混凝土早期在较短时间内快速成型和提升力学性能,极大缩短养护周期,提高生产效率,是颇具大规模工业化应用前景的二氧化碳利用方式。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。二氧化碳养护加气混凝土配方主要由试件的抗压强度和固碳性能共同决定。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4 d后的加气混凝土进行2 h 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形貌,如球状和纺锤形等,XRD分析则进一步证明了碳酸钙有3种不同晶型;CO₂养护后,孔径0.01~0.10μm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。

Investigation on CO2mineralization curing of aerated concretes

CO₂ 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 utili?zation.In this paper,the CO₂ 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 CO₂ mineralization reaction were mainly studied.The formula of carbon diox?ide 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 distri?bution before and after CO₂ curing was measured by mercury intrusion method.The results show that the carbon fixation ratio of the speci?mens 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 CO₂ concentra?tion/partial pressure of the second stage of cascade curing is,the higher the apparent carbon fixation rate of the specimens is;Under the same CO₂ curing condition,SEM observes that the products of mineralization reaction has different morphology,such as spherical and spin?dle shape,XRD analysis shows that there are three different crystal forms of calcium carbonate;after CO₂ curing,the micropores with pore diameter in the range of 0.01-0.10μm decrease significantly,and the higher the apparent carbon fixation ratio is,the more significant the filling effect on the aerated concrete is.