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热活化再生水泥砂浆的二氧化碳养护

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为提高废弃混凝土资源化利用率并降低混凝土制备综合碳排放,提出了一种热活化再生水泥砂浆二氧化碳养护方法.将含有0％～30％硅灰的废弃水泥浆体在800 ℃下热活化得到不同钙硅质量比的再生胶凝材料,经梯度二氧化碳养护制备低碱度再生砂浆,并分析了再生砂浆的抗压强度、物相组成和微观结构.结果表明:掺入0％和10％硅灰所得的再生胶凝材料矿物组成为C3S、β-C2S和α'-C2S,二氧化碳养护后生成大量方解石和球霰石;而掺入20％和30％硅灰后矿物组成主要为α'-C2S和CS,二氧化碳养护后的碳化产物主要为方解石和文石.再生砂浆抗压强度均高于45 MPa,含20％硅灰再生胶凝材料制作的砂浆样品抗压强度达到64.7 MPa.砂浆样品pH值降低至9.4,可有效缓解纤维增强复合材料在高碱性环境下的性能退化.
Carbon dioxide curing of mortar produced with thermally activated recycled cement
A method for carbon dioxide curing of mortar produced with thermally activated recycled cement was proposed to improve the resource utilization for waste concrete and reduce the overall carbon dioxide emis-sion during concrete preparation.The waste cement paste containing 0％to 30％silica fume was thermally ac-tivated at 800 ℃ to obtain reactivated cementitious materials with different calcium-to-silica ratios.The mortar with low alkalinity was prepared by gradient carbon dioxide curing.The compressive strength,phase assem-blage,and microstructure of mortars were analyzed.The results show that the mineral composition of the reac-tivated cementitious materials obtained by mixing 0％and 10％silica fume is tricalcium silicate(C3S),β-di-calcium silicate(β-C2S),and α'-C2S,and a large amount of calcite and vaterite is formed after carbon diox-ide curing.However,the mineral composition is mainly α'-C2S and monocalcium silicate(CS)after adding 20％and 30％silica fume,and the carbonation products are mainly calcite and aragonite after carbon dioxide curing.The compressive strength of the mortar samples after carbon dioxide curing is higher than 45 MPa,and the compressive strength of the mortar samples produced with reactivated cementitious materials containing 20％silica fume achieves 64.7 MPa.The pH of the mortar specimens is reduced to 9.4,which can effectively mitigate the performance degradation of fiber reinforced polymer in highly alkaline environments.

reactivated cementitious materialslow-pHcarbon dioxide curingsilica fume

李烨、王浩东、孙晖、刘铁军

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哈尔滨工业大学(深圳)土木与环境工程学院,深圳 518055

中建科技集团有限公司,北京 100195

再生胶凝材料 低碱度 二氧化碳养护 硅灰

国家杰出青年科学基金资助项目广东省自然科学基金资助项目深圳市科技研发资金资助项目深圳市科技研发资金资助项目哈尔滨工业大学(深圳)高性能土木工程材料国家重点实验室开放基金资助项目

520250812023A1515012635KQTD20210811090112003GXWD202208171439190022021CEM006

2024

10.3969/j.issn.1001-0505.2024.01.011

东南大学学报(自然科学版)
东南大学

东南大学学报(自然科学版)

CSTPCD北大核心
影响因子：0.989
ISSN：1001-0505
年,卷(期)：2024.54(1)
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