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Researchers at AUST Re-engineer Earth-based Composites for Low-cost Housing Solutions

At AUST, a building material as old as civilization itself is being re-engineered as a modern construction material and adapted to industrial processing methods using recent advances in materials science and engineering. Doctoral candidate in the Materials Science and Engineering Department, Emeso Ojo, says engineered earth-based composites have potential to meet increasing infrastructural demands in tandem with the present global drive towards achieving sustainability in the building construction sector. Due to their eco-friendly indices, enhanced by their availability, earth-based construction materials have re-emerged as an attractive and viable construction material in recent times. Her research, which is part of a collaborative partnership between the Pan African Materials Institute (PAMI) of AUST, and Research Nucleus on Materials for Biosystems of University of São Paulo, Brazil, focuses on the alkali activation of clays typically found in soils as binding mechanism alongside inclusion of natural and synthetic fibres as reinforcements to improve mechanical properties of this class of materials. She also explored the adaptability of this technology for industrial scale production using extrusion moulding as processing technique. 

Evaluation of mechanical properties of fibres at the AfDB Laboratory

Evaluation of mechanical properties of fibres 

The research presented a comparative analysis of the reinforcing effect of different fibre types (sisal, Eucalyptus pulp microfibers and polypropylene), in an alkali activated stabilized soil, to give insight on effect of fibre type and content on physical and mechanical properties of the composites. The results show that fibres and alkaline activators significantly improve properties of earth-based composites through distinct fibre-soil interactions which control composite performance.


Conducting nano-indentation tests on soil-fibre 

She adopted a multi-scale approach using nano-indentation and macro-mechanical testing to study the mechanical behavior of the composites to further understand the strengthening and toughening contributions of natural and synthetic fibres for this class of materials. At the scale where mechanics meets chemistry, results from the nano-indentation showed natural fibre reinforcements altered microstructure by influencing the formation of binder phases within the alkali activated systems. Hydrophillic sisal fibres absorbed alkali activation solutions thereby reducing the degree of alkali activated binder phases in the soils. The understanding gained from this approach may help expand the scope of application of earth-based building materials and ultimately inspire engineers to design composites for a wide range of structural applications. In countries like Nigeria and Brazil, these building materials have potential to meet increasing housing demands in line with targets set by the sustainable development goals (SDGs). ‘I am motivated by the abundant natural resources in these parts of the world and seek to apply insights from studies on material behavior for the design of sustainable and robust building materials particularly for low-cost housing solutions’, she says.


Technical details of this study can be found here

Contact on this study: Dr Emeso Beckley Ojo