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Starches and its derivatives are known to exhibit viscosity modifying characteristics. In an ongoing work, the influence of com and cassava starches on some properties of concrete such as compressive strength, heat of hydration and creep are examined. Various percentages (0.0, 0.5, 1.0, 1.5 and 2 %) of starches by weight of cement were added to concrete mixes prepared in the laboratory. Preliminary results of compressive strengths showed that both starches have some positive impact (e.g. there was 5.3 % increase in strength due to a 1 % addition of com starch by weight of cement in comparison to the control while cassava starch of the same percentage gave 4.9 % increase in strength) at certain percentages of starch addition to concrete at 28 days. The creep and hydration results shows the starch additions compares well and in some instance performs better.
The construction sector generally shows a great contribution to socio-economic development in Africa, and has particularly enhanced the continent's employment sector over the last few years. The African concrete construction sector is quite different when compared to its European and/or American counterparts. Modem infrastructural development exists in many urban cities in Africa, but this is at variance with rural areas, which tend to have little or no basic amenities such as sound road networks, solid and affordable shelter, and potable water. A large percentage of the construction activities are observed through the informal construction sector which mainly constitutes of cheap labour. This paper gives a basic introduction into the necessities for infrastructural development in Africa with focus on the construction sector. The paper addresses the practised construction activities based on the informal construction sector as well as suggests sustainable construction approaches sufficient for the African rural communities to benefit from the available economy. A better understanding of this sector is required which can help improve the existing methods of construction rather than adopt the construction techniques observed from the developed countries.
The use of starch and its derivatives in concrete as an admixture to modify relevant properties of concrete is on the increase in recent times. It is known to modify the rheology, to affect the hydration kinetics of cement, and influence on initial and final setting time of cement. This paper examines the effect of cassava starch on concrete. shrinkage properties of concrete, with and without starch addition, were studied. Various percentages (0, 0.5, 1.0, 1.5 and 2 %) of starches by weight of cement were added to concrete mixes prepared in the laboratory. Shrinkage tests were conducted for duration of up to one year. The result show that concretes with starch additions exhibit lower shrinkage, which is an indication the addition of starch as admixture in concrete improves the ability of the concrete reduce shrinkage problems.