Characterization of Selected Nigerian Kaolinites and Agricultural Waste Ashes as Materials for Sustainable Geopolymer Brick Manufacturing

Abstract

There have been reports of an increasing rate of green house gas emissions from different sources resulting to adverse climatic changes all over the world. 2018 BBC Chatham House report stated that about 8% of the worlds CO₂ emission come from cement production. Hence the need to look at alternative sources of cement production which would not compromise the expected strength and efficiency in building constructions as well as reduce CO₂ emission into the environment. This research presents an empirical study that investigates the Characterization of Selected Nigerian Kaolinites and agricultural waste ashes (Rice Husk Ashes) as materials for sustainable geopolymer brick manufacturing. A variety of parameters including solid-to-solid mix ratio, solid-to-liquid mix ratio, liquid-to-liquid mix ratio, presence of sand filler, curing duration, water absorptivity, and bulk density were examined to understand the extent or degree of geopolymerization as well as their influence on the mechanical properties of the clay-based geopolymers. From the results, it was observed that compressive strength of the geopolymer mixes increases with time progressively from 7days through 28days with Ikere clay sample of solid-to-liquid ratio 2.0 giving the highest compressive strength. The compressive strength test carried out on Rice Husk Ash-Clay geopolymers showed a tremendous increase in strenghth compared to the ones synthesised with clay samples alone. The geopolymer bricks also showed impressive strength with time increasing progressively from 7days through 28days. However, the geopolymer binders as well as the bricks produced with Ikere clay showed a greater compressive strength than that produced with Ikare clay samples. It was also observed that bricks made from RHA-CLAY geopolymer showed impressive strength compared to that made from ordinary Portland cement. It is obvious from these results that geopolymers could be a good alternative to contemporary method of cement production since it is more environmentally friendly.