Small scale agro-based industries for community development: a case study of Asunafo South District

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Date
2005-11-03
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Sandcrete blocks are prismatic units manufactured from lean (sand-cement) mortar mixes and are the predominant walling materials used in buildings in Ghana and other developing countries. Although the blocks are preferred to other similar walling materials such as bricks and concrete blocks due to the availability of the dominant material (sand) in the country and the ease of manufacture, the material is known to have several drawbacks: it has a low compressive strength which could be a factor for structural failure in buildings. Apart from the compressive strength, little is known about the other strength and permeation properties of the material. Thirdly, little research has been conducted into the influence of water-cement ratio which is known to wield a strong influence on the strength and permeation properties of cementitious materials. On the basis of a thorough review of the literature, a detailed experimental programme was designed and carried out in Ghana and the United Kingdom on the factors that influence the strength and permeation properties of the material using over 10 destructive, partially destructive and non-destructive test methods. Over 1500 sandcrete blocks were moulded and tested. The literature review also indicated that lack of quality control in the Ghanaian sandcrete blocks manufacturing industry account for the poor quality of the material in the country. The results of the experimental programme indicate that with the right constituent materials, manufacturing and curing processes, it is possible to improve the compressive strength of sandcrete blocks to over 7.0 N/mm2 with a lean mix of 1:12 cement/sand ratio. The compressive strength of the material was found to have a strong relationship with other strength properties of the material and could therefore be used as the main criterion for determining its quality. The inclusion of quarry dust and coarse aggregate significantly improved the strength and permeation properties of the blocks. Compared with normal concrete, sandcrete was found to have a relatively high permeability. Through this study, a data base on several strength and permeation properties has been developed which can assist engineers to estimate these properties. Finally recommendations were made on ways of improving the quality of sandcrete blocks in the country.
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A Thesis submitted to the School of Graduate Studies Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfillment of the requirements for the Degree of Master of Science in Development Planning and Management, 2005
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