Study of performances and microstructures of mortar with calcined low-grade clay. (11th April 2022)

• Record Type: Journal Article
• Authors: Zheng, Dapeng; Liang, Xinwen; Cui, Hongzhi; Tang, Waiching; Liu, Wei; Zhou, Ding
• Is Part Of: Construction & building materials. Volume 327(2022)
• Publication Date: 2022-04-11
• Subjects: Calcined low-grade clay -- Supplementary cementitious material -- Pozzolanic reactivity -- Cement -- Microstructures; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2022.126963
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Low-grade clay with 14.6% kaolinite was used as supplementary cementitious material. The kaolinite transformed from crystalline phase to amorphous metakaolin phase at 600 °C. The low-grade clay calcined between 700 and 800 °C has significant pozzolanic activity. The suitable content of calcined low-grade clay in cement is 10–20 wt%. Abstract: This paper studied the effect of calcination temperatures (600–900 °C) on physical characteristics and microstructure changes of low-grade clay containing 14.6% kaolinite and 17.8% 2:1 clay mineral. The pozzolanic activity of calcined low-grade clay as a supplementary cementitious material was evaluated using strength activity index and relative strength index. The results show that the kaolinite transformed from crystalline phase to amorphous metakaolin phase at 600 °C, while the particle size of clay first increases and then decreases. The optimal calcination temperature is found between 700 and 800 °C, whereas the optimal cement replacement level is 10–20 wt%.