Document Type

Report

Publication Date

Winter 2024

Abstract

This project aimed to assess the feasibility of using locally sourced calcined kaolinitic clays both as supplementary cementitious materials (SCMs) and as precursors for synthesizing geopolymers (GPs). For SCMs, a comprehensive set of characterizations was conducted, including X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), particle size analysis, and loss on ignition (LOI), along with evaluations of concrete properties such as strength activity index (SAI), slump, air content, compressive strength, and surface resistivity. For GPs, compressive strength was tested. The study yielded several key findings: (1) Three types of calcined clays (CCs) were analyzed based on kaolinite content: high (>90% kaolin, UPF & LPC), medium (>75% kaolin, TNKY & GLA), and none (MIL); (2) All tested CCs adhered to ASTM C618 standards regarding moisture content and LOI and fulfilled the strength activity index required by the same standard; (3) The ideal replacement level for UPF, LPC, and TNKY was 30%; for GLA, it was 20%; and for MIL, 10%; (4) According to AASHTO T358, all calcined clay samples exhibited low or very low chloride ion penetration (CIP) levels; (5) Calcination temperature had a more significant effect on GP binder strength than calcination duration, with UPF-700, LPC-700, and TNKY-800 showing the highest strength, comparable to GP compositions synthesized with commercially available metakaolin. In conclusion, these results suggest that all calcined clays can be effectively used as both SCMs and GP precursors in the construction of concrete.

Comments

Tran-SET Project 22CLSU13

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