Insights into clinker-clay interactions in stabilized soft clay using NMR, TEM, and FTIR
Jun Wu, Changming Wan, Zhen-Shun Hong, Annan Zhou, Yunzhi Tan, Yongfeng Deng
Abstract
Interactions between cement clinkers and clay minerals are crucial to the much lower strength of cement-based stabilized clays than concrete or mortar. In this paper, the kaolinite-based and montmorillonite-based clays were respectively stabilized by tricalcium silicate (C 3 S) and tricalcium aluminate (C 3 A), and measured by the unconfined compressive strength (UCS), 29 Si/ 27 Al solid state nuclear magnetic resonance (SS-NMR), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscope (TEM) to probe the clinker-clay mineral interaction from macro-mechanical, mineralogical, and microstructural perspectives. The results show that C 3 A-stabilized samples gain strength rapidly in the first 3 d but are only 20%- 60% of the strength of C 3 S-stabilized ones after 60 d. Microstructures reveal that montmorillonite shows better pozzolanic reactivity due to its superior Si-chain and lattice substitution compared to kaolinite. This interaction domains the engineering performance of stabilized clays, benefiting the design of stabilizer referring to as the industrial by-products and clay minerals.