Kaolin-Metakaolin Crystallographic Transformation and the Durability of Metakaolin-Based Geopolymer Concrete

Abiodun, Yetunde; Adeosun, Samson

doi:10.21608/eijest.2022.136365.1154

Kaolin-Metakaolin Crystallographic Transformation and the Durability of Metakaolin-Based Geopolymer Concrete

Document Type : Original Article

Authors

Yetunde Abiodun ¹
Samson Adeosun ²

¹ Department of Civil and Environmental Engineering, Faculty of Engineering, University of Lagos, Nigeria

² Department of Metallurgical and Materials Engineering, Faculty of Engineering, University of Lagos, Lagos, Nigeria. & Industrial Engineering Department, Durban University of Technology, Durban, South Africa

10.21608/eijest.2022.136365.1154

Abstract

The quest to reduce and eliminate the resultant health hazards posed by the continued use of cement in structural works has led to the emergence of metakaolin-based geopolymer as a viable alternative to cement. Kaolin was explored as a material for metakaolin production from four Nigerian deposits: Imeko, Okpela, Ifon and Isan-Ekiti. Metakaolin was obtained by calcining kaolin samples at temperatures ranging from 500°C to 1000°C for 30, 60, 120, and 180 minutes at an interval of 100°C. ImageJ software was used to measure the area of particles present in each sample micrograph obtained from Scanning electron microscopy. The metakaolin samples were also subjected to atomic absorption spectroscopy and X-ray diffraction examinations. Metakaolin samples were classed as class N pozzolan and X-ray diffraction spectroscopy revealed the presence of amorphous silica in metakaolin and distinct crystal systems were detected using a crystallography test on the samples. The chloride permeability test according to ASTM C1202 indicated that Metakaolin-based geopolymer concrete (Mk-GPC) showed a significant decrease in the charges passing through at 28 days when compared to 90 days. This trend was similar to the result obtained from OPC-concrete when charges were passed through the samples. This shows that both Mk-GPC and OPC-concrete can be considered acceptable for the protection of embedded steel reinforcement from corrosion in real-life construction works as they have good resistance to chloride permeability. According to this research finding, metakaolin-based geopolymer could be used as a sustainable alternative to cement in Nigeria.

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