Comparative Cost Analysis of Precast and In Situ Concrete Floor Slabs in Ghana

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There is a huge housing deficit in Ghana. As a result, majority of people in both rural and urban communities put up their own houses. The principal factor clients consider before initiating projects is cost. Precast and in situ reinforced concrete are widely used in the construction industry for the construction of suspended floor slabs. An informal survey conducted by the researcher showed that the use of cast in situ reinforced concrete slab surpasses the use of precast concrete slabs. In Ghana, it costs one a lifetime to put up a decent accommodation. Others have found the need to put up commercial and other buildings for renting using sub-standard materials or compromising on standards, all in the name of cutting down cost. In doing this some have compromised on quality to the detriment of society. There is the need to explore other alternatives and avenues that meet quality standards at a reduced cost. The purpose of this study was to analyse and compare the initial cost of precast and in situ reinforced concrete slabs. The study made use of descriptive research design and quantitative approach. Estimates of precast/prestressed beams and hollow blocks as well as Bills of Quantities were prepared from the structural drawings of slabs and beams of the suspended floors for the study. Results from the study confirmed that the initial cost of constructing a precast floor slab is cheaper than the cast in situ, and the cost savings made depends on the function of the building as its design parameters are not the same. The recommendation made were: the use of precast floors must be encouraged, prestressed beam and block precast slab could be adopted as oversight concrete slab in water logged area to avoid hardcore filling which aids rising damp and awareness of the cost reduction in the use of precast floors must be created. Further research works that arose from the study were: a study into the feasibility of using iv other precast elements like beams and column in Ghana, a survey must be conducted to see society‟s readiness to use the precast floor system and a study to find out if pretensioned cables could be used to reduce the amount of reinforcement in slabs and a study to find the whole life cycle cost of precast and in situ floor slabs.
A Thesis Submitted to the Department of Building Technology, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the award of a degree of Master of Science in Construction Management.