Reactivity of calcined chikoko clay and its influence on the strength properties of concrete
Department of Civil Engineering, University of Agbor Delta, Nigeria.
Research Article
Open Access Research Journal of Engineering and Technology, 2025, 09(02), 066-077.
Article DOI: 10.53022/oarjet.2025.9.2.0097
Publication history:
Received on 21 October 2025; revised on 30 November 2025; accepted on 03 December 2025
Abstract:
This study investigates the reactivity of calcined Chikoko clay and its influence on the mechanical performance of ordinary Portland cement concrete. Locally sourced Chikoko clay, an aluminosilicate material, was calcined at controlled temperatures of 200, 400, 600, and 800°C and incorporated into concrete at replacement levels of 5, 10, 15, and 20% by mass. The clay was characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis (TGA), BET surface area analysis, Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) to assess its chemical composition, mineralogical transformation, and microstructural features. Concrete specimens were tested for compressive strength, splitting tensile strength, and modulus of elasticity at curing ages of 7, 28, 56, and 90 days. Results show that both calcination temperature and replacement level significantly influence concrete strength, with optimal performance observed at 10% replacement. The highest 90-day compressive strength of 52.3 MPa was achieved at 800°C, indicating strong pozzolanic reactivity of thermally activated clay. Excessive replacement (>15%) reduced strength due to dilution of the cementitious content. Microstructural analysis confirmed denser pore structures and enhanced hydration in calcined clay blends. The findings demonstrate that calcined Chikoko clay is a highly reactive supplementary cementitious material capable of improving long-term concrete strength while offering potential for sustainable, low-carbon concrete production.
Keywords:
Chikoko clay; Calcination; Pozzolanic reactivity; Concrete strength
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