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Investigation on the microstructure-related characteristics to elucidate performance of composite cement with limestone-calcined clay combination
Cement and Concrete Research ( IF 10.9 ) Pub Date : 2020-03-01 , DOI: 10.1016/j.cemconres.2019.105959
Yuvaraj Dhandapani , Manu Santhanam

Abstract This paper discusses the role of physical structure alterations on three binder types: plain portland cement, fly ash-based binder and calcined clay-limestone binder. The kinetics of physical structure development and the relevance in transport properties were distinguished using an interlinked parameter in concrete and paste. A systematic experimental investigation was carried out on a range of critical parameters such as strength development, resistivity development, transport characteristics and the time-dependent change in transport parameter. The role of microstructure in terms of the chemical composition of C-A-S-H and its physical states in the different systems is identified as the critical factor governing the development of microstructure. Chloride resistance was assessed by chloride migration experiments for a period of 4 years. The durability behaviours of the concrete with various binder were generalised using pore network parameters such as formation factor and tortuosity. A sensitivity analysis was used to dissect the contribution of the pore solution dilution and pore connectivity to the change in the pore network parameter. Based on the rise in macroscopic physical characteristics (i.e., formation factor here), a two-fold structure development mechanism to conceptualise microstructural evolution in cement composites is presented. Initially, capillary pore space reduces to a critical size range (i.e., 10–30 nm), which is followed by the densification of the physical state of the microstructure. At the point of densification, the pores become largely disconnected which leads to a dramatic increase in the formation factor. The binding matrix in calcined clay concretes reaches the critical pore size at an early age which leads to early densification of capillary pore space region in comparison to fly ash concretes.

中文翻译:

石灰石-煅烧粘土组合复合水泥微结构相关特性研究

摘要 本文讨论了物理结构改变对三种粘结剂类型的作用:普通硅酸盐水泥、粉煤灰基粘结剂和煅烧粘土-石灰石粘结剂。物理结构发展的动力学和传输特性的相关性使用混凝土和糊状物中的相互关联的参数进行区分。对一系列关键参数进行了系统的实验研究,例如强度发展、电阻率发展、输运特性和输运参数随时间的变化。微观结构在 CASH 的化学成分及其在不同系统中的物理状态方面的作用被确定为控制微观结构发展的关键因素。通过为期 4 年的氯化物迁移实验评估耐氯化物。使用孔隙网络参数(例如地层系数和曲折度)对具有各种粘合剂的混凝土的耐久性行为进行了概括。使用敏感性分析来剖析孔隙溶液稀释和孔隙连通性对孔隙网络参数变化的贡献。基于宏观物理特性(即这里的地层因素)的增加,提出了一种双重结构发展机制来概念化水泥复合材料的微观结构演变。最初,毛细孔空间减小到临界尺寸范围(即 10-30 nm),随后是微观结构物理状态的致密化。在致密化点,孔隙变得在很大程度上断开,这导致地层因子急剧增加。
更新日期:2020-03-01
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