城市固体废弃物焚烧飞灰对地质聚合物混凝土力学性能和微观结构的影响
Effect of Municipal Solid Waste Incineration Fly Ash on the Mechanical Properties and Microstructure of Geopolymer Concrete.
作者信息
Niu Mengya, Zhang Peng, Guo Jinjun, Wang Jia
机构信息
School of Water Conservancy Engineering, Zhengzhou University, Zhengzhou 450001, China.
出版信息
Gels. 2022 May 30;8(6):341. doi: 10.3390/gels8060341.
Geopolymers are environmentally friendly materials made from industrial solid waste with high silicon and aluminum contents, and municipal solid waste incineration fly ash (MFA) contains active ingredients such as Si, Al and Ca. According to this fact, a green and low-carbon geopolymer concrete was prepared using MFA as a partial replacement for metakaolin in this study. The mechanical properties of the MFA geopolymer concrete (MFA-GPC) were investigated through a series of experiments, including a compressive strength test, splitting tensile strength test, elastic modulus test and three-point bending fracture test. The effect of the MFA replacement ratio on the microstructure of MFA-GPC was investigated by SEM test, XRD analysis and FTIR analysis. MFA replacement ratios incorporated in GPC were 5%, 10%, 15%, 20%, 25%, 30%, 35% and 40% by replacing metakaolin with equal quality in this study. In addition, toxic leaching tests of MFA and MFA-GPC were performed by ICP-AES to evaluate the safety of MFA-GPC. The results indicated that the mechanical properties of MFA-GPC decreased with the increase of the MFA replacement ratio. Compared with the reference group of GPC without MFA, the maximum reduction rates of the cubic compressive strength, splitting tensile strength, axial compressive strength, elastic modulus, initiation fracture toughness, unstable fracture toughness and fracture energy of MFA-GPC were 83%, 81%, 78%, 93%, 77%, 73% and 61%, respectively. The microstructure of MFA-GPC was porous and carbonized; however, the type of hydrated gel products was still a calcium silicoaluminate-based silicoaluminate gel. Moreover, the leaching content of heavy metals from MFA-GPC was lower than that of the standard limit. In general, the appropriate amount of MFA can be used to prepare GPC, and its mechanical properties can meet the engineering requirements, but the amount of MFA should not be too high.
地质聚合物是由高硅和铝含量的工业固体废物制成的环保材料，而城市固体废物焚烧飞灰（MFA）含有硅、铝和钙等活性成分。基于这一事实，本研究使用MFA部分替代偏高岭土制备了绿色低碳地质聚合物混凝土。通过一系列试验研究了MFA地质聚合物混凝土（MFA-GPC）的力学性能，包括抗压强度试验、劈裂抗拉强度试验、弹性模量试验和三点弯曲断裂试验。通过扫描电子显微镜（SEM）试验、X射线衍射（XRD）分析和傅里叶变换红外光谱（FTIR）分析研究了MFA替代率对MFA-GPC微观结构的影响。本研究中，通过等量替代偏高岭土，MFA在GPC中的替代率分别为5%、10%、15%、20%、25%、30%、35%和40%。此外，通过电感耦合等离子体发射光谱仪（ICP-AES）对MFA和MFA-GPC进行了有毒元素浸出试验，以评估MFA-GPC的安全性。结果表明，MFA-GPC的力学性能随着MFA替代率的增加而降低。与不含MFA的GPC参考组相比，MFA-GPC的立方体抗压强度、劈裂抗拉强度、轴心抗压强度、弹性模量、起裂断裂韧性、失稳断裂韧性和断裂能的最大降低率分别为83%、81%、78%、93%、77%、73%和61%。MFA-GPC的微观结构为多孔碳化结构；然而，水化凝胶产物的类型仍然是钙硅铝酸盐基硅铝酸盐凝胶。此外，MFA-GPC中重金属的浸出含量低于标准限值。总体而言，适量的MFA可用于制备GPC，其力学性能能够满足工程要求，但MFA的用量不宜过高。
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