利用H_(2)O_(2)发泡和碳化养护改善RMFC的固碳、力学和保温隔热性能  

Improving Carbon Sequestration,Mechanical Properties and Thermal Insulation of RMFC by Foaming with H_(2)O_(2) and Carbonization Curing

作　　者：刘奎周 张建仁[1,3] 田湘 黄敦文 彭晖[1,3] LIU Kuizhou;ZHANG Jianren;TIAN Xiang;HUANG Dunwen;PENG Hui(School of Civil Engineering and Architecture,Changsha University of Science and Technology,Changsha 410114,China;College of Civil Engineering,Hunan University,Changsha 410082,China;Key Laboratory of Safety Control of Bridge Engineering of Ministry of Education,Changsha University of Science and Technology,Changsha 410114,China)

机构地区：[1]长沙理工大学土木工程学院,长沙410114 [2]湖南大学土木工程学院,长沙410082 [3]长沙理工大学桥梁工程安全控制教育部重点实验室,长沙410114

出　　处：《材料导报》2023年第23期29-36,共8页Materials Reports

基　　金：国家自然科学基金(51878068);湖南省杰出青年基金(2017JJ1027);湖南省研究生科研创新项目(QL20210189)。

摘　　要：开发新型低碳胶凝材料替代高能耗高碳排放的硅酸盐水泥是水泥与建筑行业碳减排的重要途径之一。通过H_(2)O_(2)发泡和CO_(2)养护活性氧化镁水泥(Reactive magnesium oxide cements,RMC),制备了一种可快速大量固碳且具有保温隔热性能的活性氧化镁泡沫混凝土(Reactive magnesium oxide foam concrete,RMFC),并研究得到了各因素对材料发泡、固碳、力学及隔热性能的影响规律及作用机理。考察了水灰比、H_(2)O_(2)掺量和H_(2)O_(2)预热温度对RMC浆体发泡效果的影响规律;研究了孔隙率、养护条件和碳化时间对RMFC碳化行为的作用效果;分析了孔隙率、养护条件与碳化时间对RMFC力学性能和保温隔热性能的作用机理。研究表明:通过适当提高水灰比延长RMC浆体初凝时间、预热H_(2)O_(2)提高其分解速率,可制备得到孔隙率较高的RMFC;提高孔隙率、增加CO_(2)浓度和降低碳化温度可显著提升固碳率,碳化温度不同还导致碳化产物有所不同;降低孔隙率或提高碳化水平可得到强度较高但导热系数较大的RMFC;试验中制备得到了容重635~1335 kg/m^(3)、抗压强度3.75~9.1 MPa,导热系数0.32~0.49 W/(m·K)的RMFC。本工作提出的RMFC制备方法具有显著的固碳效果,试验中每吨RMC固定CO_(2)的最大值为0.42 t,以其替代硅酸盐水泥泡沫混凝土可助力水泥与建筑行业实现“碳达峰、碳中和”。Developing new low-carbon cementitious materials to replace high-energy consumption and carbon emission ordinary Portland cement is one of the critical approaches for carbon reduction in the cement and construction industries.In this study,we prepared a rapidly carbon-sequestering and thermally insulating material,reactive magnesium oxide foam concrete(RMFC),by foaming reactive magnesium oxide cement(RMC)with H_(2)O_(2) and curing with CO_(2).We investigated the influence of factors such as water-ash ratio,H_(2)O_(2) dosage,and H_(2)O_(2) preheating temperature on the foaming behavior of RMC paste.Additionally,we studied the effects of porosity,curing conditions,and carbonation time on the carbonation behavior of RMFC,and analyzed the mechanisms governing the impact of porosity,curing conditions,and carbonation time on the mechanical and thermal insulation properties of RMFC.The results showed that by appropriately increasing the water-ash ratio,we could extend the initial setting time of RMC paste,while preheating H_(2)O_(2) enhanced its decomposition rate,enabling the production of high-porosity RMFC.Furthermore,increasing porosity,elevating CO_(2) concentration,and reducing carbonation temperature significantly enhanced the CO_(2) sequestration rate.Different curing temperatures led to variations in carbonation products.Reducing porosity or increasing the carbonation level resulted in higher strength but higher thermal conductivity in RMFC.Through experimentation,we achieved RMFC with densities ranging from 635 kg/m^(3) to 1335 kg/m^(3),compressive strengths between 3.75 MPa and 9.1 MPa,and thermal conductivities of 0.32 W/(m·K)to 0.49 W/(m·K)after carbonation curing for 12 h to 48 h.The proposed method for RMFC preparation demonstrated a substantial CO_(2) sequestration effect,with a maximum CO_(2) sequestration of 0.42 tons per ton of RMC.Replacing ordinary Portland cement foam concrete with RMFC has the potential to contribute to carbon emissions reduction in the cement and construction industries.

关 键 词：活性氧化镁水泥(RMC) CO_(2)养护 泡沫混凝土 力学性能 导热系数 

分 类 号：TU528[建筑科学—建筑技术科学]