Thesis--PlanB (M.S.)--University of Wisconsin--Stout, 1998. / Includes bibliographical references.

Thesis (M.S.H.P.)--Ball State University, 2009. / Title from PDF t.p. (viewed on Nov. 30, 2009). Includes bibliographical references (p. 69-72).

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For a pre-cast concrete manufacturing company to obtain a Botswana Bureau of Standards (BOBS) certification time, money and effort have to be spent and yet it is not known whether the consumers will use the BOBS certification as a buying decision factor. The Botswana Bureau of Standards certified pre-cast concrete manufacturing companies have to comply with rigorous inspections to ensure that standards are maintained. Competition in the concrete manufacturing industry is contested by certified companies and uncertified companies and yet the market is shared amongst these players. This dissertation will endeavour to analysis the effects of Botswana Bureau of Standards certification on buyer decision on pre-cast concrete products in Gaborone Botswana. Therefore, the research findings will establish whether BOBS certification can be used as marketing tool. A sample of forty was drawn from the population in Gaborone to represent the whole of Botswana. Date was collected using both semi-structured and structured questionnaires. Responses were sorted according to similarities and then interpreted. Results in this research indicated that BOB certification influences concrete consumers' decisions. It was also indicated that BOB certification is actually a marketing tool that sways positively concrete products buyers' decisions. Therefore, it was recommended that concrete manufacturers should exploit this marketing tool to gain a larger market share. Those concrete products manufacturers whose products are not certified should consider this marketing tool in their marketing strategy in order to remain competitive. BOBS must also launch a massive public awareness to popularise the use of the certification by the manufacturers. Lastly, It is recommended that the Botswana Government must continue supporting BOBS to improve quality standards in the country. / (MBA) North-West University, Mafikeng Campus, 2005

CO2 absorption behaviour of four commonly used cement based building products: cement paste, concrete block, expanded polystyrene bead (EPB) and cement-bonded cellulose fiberboard are studied. Cement products are manufactured following industry formulation and process, and carbonation curing takes place in a chamber under a pressure of 0.5 MPa, at ambient temperature, for durations of mostly 2 to 8 hours with both pure carbon dioxide gas and flue gas. The flue gas of 13.8% CO2 content is collected from a typical cement kiln without separation. Influencing factors on carbon uptake, long-term strength as well as microstructure development are studied. / It is found that the CO2 uptake ability of those cement-based products follows the same order when exposed to either pure gas or flue gas: fiberboard has the highest uptake capacity, followed by cement paste, bead board and concrete. For fiberboard, the best CO2 uptake in flue gas is 8.1%, it reaches 23.6% if pure gas used. Introduction of cellulose fiber in the fiberboard significantly increases voids volume and cement paste surface area through dispersing the paste onto fiber surface, effectively increasing carbonation reaction sites and thus CO2 uptake. / For pure gas carbonation with high reaction rate, it takes longer time for carbonated products to further develop strength from subsequent hydration, due to the high water loss during carbonation, the densified cement matrix structures and even fast decalcified cement minerals. Fast carbonation with pure gas is detrimental to cement paste in its long-term strength. For flue gas carbonation, both immediate strengths and long-term strength of the products are comparable with those by pure gas carbonation, although with less CO 2 uptake ability. / Five CO2 uptake determination methods are evaluated. Weight gain method is suitable for both pure gas and flue gas carbonation systems. Mass curve method is more suited for pure gas carbonation. For flue gas carbonation, CO2 concentration method agreed well with the weight gain method. Pressure drop method is relatively less accurate because of water vapor generation during carbonation.

Carbonation curing of concrete products has shown potentials for CO2 capture and storage with environmental, technical and economical benefits in global greenhouse gas mitigation exercise. The primary objective of this study is to investigate the effect of early age carbonation on mechanical performance and pH of concrete in an attempt to understand the process and promote large scale applications. / It was found that significant early strength was developed in cement and concrete through early age carbonation curing. The early strength could be maintained and improved due to subsequent hydration. Twenty-eight-day strength of carbonated cement and concrete was comparable to that of hydrated reference if subsequently cured in the air in a sealed bag, but was lower if subsequently cured in water. Treatment with either internal curing using lightweight aggregates or chemical admixture can effectively enhance late strength development in carbonated concrete. / For three typical cement-based products including cement paste compacts, concrete compacts and precast concrete, two-hour carbonation reduced pH value from 12.8 to 11.8 as the lowest and subsequent 28-day hydration could slightly increase pH by 2% as maximum. At any time pH of early age carbonated concrete was always higher than 11.5, a threshold value under which the corrosion of reinforcing steel is likely to occur in concrete. The high pH in early-age carbonated concrete was likely attributed to the fact that early age carbonation was an accelerated hydration process, which was totally different from weathering carbonation in which pH of concrete could be neutralized due to the decomposition of calcium hydroxide and calcium silicate hydrates gel. Therefore, early age carbonation technology is applicable not only to concrete products such as masonry units and paving stones, but possibly to precast concrete with steel reinforcement as well.

No description available.

No description available.