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Synthesis and Characterization of Local Bio-Sourced Geopolymer Binder: Application to Compressed Earth Blocs



Author(s)

Marx Ferdinand Ahlinhan¹, Edem Chabi², Dorothée Djenou¹, Orphée Dansou¹, Franklin Sedoka¹, Alain Akponon¹ and Edmond Codjo Adjovi¹

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DOI:10.17265/2161-6213/2024.4-6.002

1. Laboratory of Study and Test in Civil Engineering (L2EGC), National High School of Public Works (ENSTP), National University of Sciences, Technologies, Engineering and Mathematics (UNSTIM), Abomey 2282 Goho, Department of Zou, Republic of Benin
2. Laboratory of Rural Engineering, School of Rural Engineering, National University of Agriculture (UNA), Idigny, Kétou 01 BP 55, Department of Plateau, Republic of Benin

The construction industry continues to rely on conventional materials like cement, which often can come with a high cost and significant environmental impact, particularly in terms of greenhouse gas emissions. To tackle the challenges of sustainable development, there is growing interest in using local available materials with low environmental impact. This study primarily focuses on synthesizing and characterizing a geopolymer binder made from local materials found in Benin to stabilize CEB (compressed earth brick). The synthesis involves combining amorphous aluminosilicate powder with a highly concentrated alkaline solution. Local calcined kaolinite clay (metakaolin) and corn cob ash obtained after calcination at 600 °C were used with a 12 M sodium hydroxide (NaOH) solution. Different mixtures of geopolymer were formulated substituting metakaolin by corn cob ash at rates of 0%, 5%, 10%, and 15% of the dry weight of the mixture. Thereafter physical and mechanical characterization tests were conducted on each formulation. Results showed that geopolymer binders containing 85% metakaolin and 15% corn cob ash exhibited the best physical and mechanical performance (e.g. 12.08 MPa for compression strength). Subsequently, this geopolymer formulation was used to stabilize CEB. Characterization revealed that CEBs stabilized with 10% geopolymer exhibit good mechanical properties (6.93 MPa), comparable to those of CEBs stabilized with 10% cement (7.40 MPa), justifying their use as load-bearing walls in construction.

Sustainable building materials, metakaolin, cob corn ash, geopolymer, CEB, eco-friendly construction.