Performance of Impure Calcined Clay as a Pozzolan in Concrete
Performance of Impure Calcined Clay as a Pozzolan in Concrete
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不纯煅烧粘土作为火山灰在混凝土中的性能
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
F. Rajabipour
中科院分区：
文献类型：
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作者：
Khashayar Jafari;F. Rajabipour
补充胶凝材料（SCM）是天然或工业副产品材料，用于改善混凝土混合物的性能，耐久性和可持续性。受传统火山灰短缺的影响，不纯煅烧粘土（CC）作为一种丰富的混凝土火山灰替代材料正受到人们的关注。在这项研究中，粘土泥浆产生的洗涤骨料在商业砂和砾石坑进行了调查。将该源粘土干燥和煅烧，并评价所得CC的性质和火山灰性能。观察到，尽管具有大的（>50%wt.）惰性石英含量，CC满足天然火山灰的所有ASTM C618-19（AASHTO M295）要求。路面级混凝土混合物含有20%CC作为水泥替代品（按重量计）产生所需的和易性和新鲜和硬化空气含量。力量发展略低于对照组。与对照（100%波特兰水泥）混合物相比，CC的使用改善了混凝土的耐久性，包括氯离子渗透、碱-硅反应和干燥收缩。此外，三元石灰石煅烧粘土水泥和矿渣煅烧粘土水泥砂浆混合物显示出优异的强度发展，同时取代近50%的波特兰水泥。
Supplementary cementitious materials (SCMs) are natural or industrial by-product materials which are used to improve the performance, durability, and sustainability of concrete mixtures. Motivated by the recent reports on shortage of conventional SCMs, impure calcined clays (CCs) are receiving attention as abundant alternative pozzolans for concrete. In this study, a clay slurry resulting from washing aggregates in a commercial sand and gravel pit was investigated. This source clay was dried and calcined, and the properties and pozzolanic performance of the resulting CC was evaluated. It was observed that despite having a large (>50%wt.) inert quartz content, the CC met all ASTM C618-19 (AASHTO M295) requirements for natural pozzolan. A pavement-grade concrete mixture containing 20%CC as a cement replacement (by weight) produced desired workability and fresh and hardened air content. Strength development was slightly below the control. The use of CC improved the durability of concrete with respect to chloride penetration, alkali–silica reaction, and drying shrinkage in comparison with a control (100% Portland cement) mixture. In addition, ternary limestone-calcined clay–cement and slag-calcined clay–cement mortar mixtures showed excellent strength development while replacing nearly 50% of the Portland cement.