FEASIBILITY OF METAKAOLIN AND LIME MATERIAL AS A BINDER MIXTURE FOR CONCRETE THE CASE OF BALENGOU CLAY IN WEST CAMEROON AND THE LIME OF FIGUIL NORTHERN CAMEROON

Abstract

Diverse complexities and challenges are faced during cement production processes especially the Portland cement. The process requires huge amounts of energy and these fossils fuels when burnt at up to 1450°C released excessive greenhouse gases such as CO₂ which contributes to the calamity called global warming. All these facts, in addition to the low economic growth of countrys, and the expensive price of construction materials, reduce the availability of a liveable, ecological and sustainable shelter house for the middle classes. It is in this line that we thought of valorising the calcined clay from Balengou by studying the feasibility of making a binder by mixing it with lime from Figuil as this could help to partially cover some domains done by Portland cement, to improve the lime mortar properties, to reduce the construction cost, and to reduce the degradation of the ozone layer. In this work, Hallosysite clay from Balengou was calcined at 750°C, mixed with lime and the effects of it at metakaolin percentage substitution to lime (10 %, 15 %, 20 %, 25% to 90 %.) were examined on their physico-mechanical properties such as Consistency, water absorption, pozzolanicity etc. In the lime-metakaolin mixture with metakaolin from Balengou’s clay, as we increase the percentage of metakaolinin the paste, the setting duration reduces. The proportion of pure lime improves the plasticity of the paste while the metakaolin at its optimum percentage (20%) increases the strength of the paste to its maximum value at about 28 days. The low energy consumption during the manufacturing process and the CO₂ absorption during the carbonation process reduce the environmental impact and cost of lime-metakaolin mixture. Also, the aesthetic appearance of that paste makes it adequate for internal pointing and plastering. At 20% of metakaolin in the paste, the pozzolanicity is at the highest point and the paste gains good plasticity and perspiration with optimum resistance. Lime-metakaolin mixture is good for works where the need of breathability and lower strength is of great importance. Then, we do not recommend it for works with high strength structural elements.