One of the continuing challenges posed by unprecedented urbanisation in Nigeria, estimated at about 5% per annum, is the provision of adequate and affordable housing. The shortage in housing, due in part to the ever-rising prices of construction materials, makes it logical to consider alternative building materials. Paradoxically, Nigeria is grappling with the challenges of managing solid waste, many of which could find suitable applications in the production of cement-, concrete- and clay-based walling, roofing and ceiling products as well as pozzolans for partial replacement for ordinary Portland cement. The objective of this chapter is to present information on the development, experimental investigations and practical application of sustainable building materials from agro-industrial wastes in Nigeria. Agroforestry residues such as bagasse and corn cob ashes have been found suitable as pozzolans; cement- and clay-bonded reinforced composite roofing tiles, hollow concrete blocks and stabilised clay bricks have been developed using a variety of lignocelluloses as sources of fibre reinforcement, while biomaterial substitutes for steel reinforcement in concrete have been tested. However, for these products to become widely acceptable, greater awareness has to be created among all stakeholders in the building construction industry, coupled with the development of appropriate building codes.
Part of the book: Sustainable Construction and Building Materials
Modern agriculture depends heavily on technology. Land clearing, irrigation, drainage, crop storage and processing all require technological input. By modernising her agriculture, through wise application of science and technology, Africa can make significant headway in economic growth. However, an agricultural technology that is too sophisticated for a particular country/region is beyond its absorptive capacity. Hence, to achieve the objectives of agricultural mechanisation in Africa, it is imperative to take into account prevailing socio-economic conditions and the level of mechanisation necessary for optimal productivity. One major constraint to agricultural mechanisation in sub-Saharan Africa is the relatively high cost of imported metallic machine and equipment fabrication materials. Taking full advantage of substitute non-metallic materials may lower the cost of production and concomitantly empower rural fabricators with limited access to electricity and welding facilities to engage in local manufacturing of sundry agricultural machines and equipment. This Chapter presents illustrative examples of full and partial substitution of metallic with non-metallic materials in the fabrication of affordable machines and equipment for agricultural production, agro-processing, irrigation and drainage, crop drying and storage. Ways of addressing identified critical challenges of technology diffusion are also discussed.
Part of the book: Technology in Agriculture