研磨活化再生微粉/多元复合胶凝材料的微观结构演变与碳足迹评价

Microstructure evolution and carbon footprint evaluation of ground activated recycled powder / multi-component composite cementitious materials

  • 摘要: 为大规模应用再生微粉(RP)替代普通硅酸盐水泥(OPC)作为辅助胶凝材料(SCM)。本研究旨在构建RP/多元复合胶凝材料(MCCM),通过抗压强度试验和XRD、FT-IR、SEM、BSE-EDS、TEM等微观测试手段,对RP/MCCM的强度发展、相组织演化和微观结构等进行了研究,并以生命周期评价(LCA)方法对RP/MCCM碳减排效益进行分析。研究发现:研磨活化后,RP掺量为30% (R30)时,28 d抗压强度在未活化的基础上提高7.6%。RP掺入后Al—OH增强,C—O和\textCO_3^2- 键峰变窄,S元素分布均匀,有利于钙矾石(AFt)和CaCO3相的生成。CaCO3、Ca(OH)2、SiO2纳米结构在RP和粉煤灰(FA)分别复掺15%时(R15F15),其三元体系中紧密的结合在一起,未出现明显的断层,从而改善了其结构致密性和强度。此外,碳排放分析发现,RP掺入降低了原材料提取和运输过程碳排放,实现了减排目标。

     

    Abstract: In order to replace ordinary Portland cement (OPC) as an supplementary cementitious material (SCM) for large-scale application of recycled powder (RP). The purpose of this study is to construct RP/multi-component composite cementitious material (MCCM). The strength development, phase structure evolution and microstructure of RP/MCCM were studied by compressive strength test and microscopic test methods such as XRD, FT-IR, SEM, BSE-EDS and TEM. The life cycle assessment (LCA) method was used to analyze the carbon emission reduction benefits of RP/MCCM. It indicates that after grinding activation, the 28 d compressive strength increased by 7.6% on the basis of unactivated value when the RP content was 30% (R30). After RP incorporation, the Al—OH is enhanced, the C—O and \textCO_3^2- bond peaks are narrowed, and the S element is evenly distributed, which is beneficial to the formation of ettringite (AFt) and CaCO3 phases. The CaCO3, Ca(OH)2 and SiO2 nanostructures are tightly bonded together in the ternary system without obvious faults appear when RP and fly ash (FA) are mixed with 15% (R15F15) respectively. Hence, the compactness and strength of the structure are improved. Moreover, the results of carbon emission analysis show that the incorporation of RP can reduce carbon emissions during raw material extraction and transportation, and achieve emission reduction targets.

     

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