Exploring low-grade clay minerals diving into limestone calcined clay cement (LC3): Characterization − Hydration − Performance
Nosheen Blouch, Khuram Rashid, Minkwan Ju
Abstract
The physicochemical properties of calcined kaolinite clay have an impact on the hydration kinetics of limestone calcined clay cements (LC 3 ). Therefore, this study compares the effects of two types of common clays, namely low-grade kaolinite (LGK) and mixed minerals (MIX), on the characterization, heat of hydration, setting times, and strength development mechanisms in LC 3 . The characterization of calcined clays is initially conducted. After conducting heat of hydration, TGA , and XRD analyses , the phase assemblage of both LC 3 and ordinary Portland cement (OPC) systems is investigated. This is followed by quantifying the amounts of AFt/AFm, portlandite , and calcite . The more amorphous nature of the LGK compared to the MIX results in the formation of Stratlingite , which contributes to gaining strength at an early age. Hemi-carbonates and mono-carbonates are useful for achieving adequate compressive strength . The LC 3 exhibits a lower heat of hydration compared to the OPC, which is advantageous in reducing the likelihood of thermal cracking in concrete structures. However, the LC 3 -MIX exhibits a higher heat of hydration after 36 h due to an excess of alkali content in the clay mixture. Moreover, the compressive strength of the LC 3 exhibited a striking similarity to that of the OPC.