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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/1578

Keywords: Hydration
Copyright: 2007
Date Added: 1-Nov-2008
Publisher: Addis Ababa University
Abstract: This research is intended to furnish comparative analysis on the effects of the different types of cements produced in Ethiopia on the durability characteristics of concrete prepared from the same. Several laboratory tests are conducted on concrete samples prepared from the various cements available in the country from different sources by keeping all the other ingredients the same. The methods of specimen preparation like mixing time and compaction effort and the subsequent curing condition are also kept identical for the different specimens. Therefore, in essence the study attempts to relate any variation in the durability characteristics of the samples to be obtained after testing only to the type of cement originally used in their preparation. Critical review of related researches undertaken in the area reveals that under the same external environmental conditions, durability characteristics of concrete are affected by its microstructure. Concrete microstructure, which is its fundamental internal structure, in turn affects the transport phenomena taking place inside it. Hence, quantitative analysis of the various transport mechanisms in concrete is a direct lead to its ability to resist deterioration over time, which is its durability. Consequently, considering the capability of the laboratory and the available funding, three of the major transport mechanisms were selected and testing was conducted on concrete samples prepared from five cements obtained from three different sources to assess their level of variability. The results are then correlated with the possible influence of the different cements on the internal structure of the concrete samples and comparative analysis is carried out. In addition, to illustrate the effects of varying cement content on each concrete sample, two types of mixes were prepared from each cement type, for normal and intermediate ranges of compressive strength, and the tests were also conducted twice at two different ages of the concrete specimens, 60 and 90 days. Besides, compressive strength measurements were taken alongside the durability tests at the ages of 56 and 91 days, in addition to, of course, the standard 28 days compressive strength test. The results indicate that in some cases, there is a significant variation in some of the most critical factors which affect durability within samples prepared from the different cements from which reasonable proximity is expected. While anticipating exactly identical results is not rational, it's alarming to find variation of magnitude as high as 100% which reflects the need for more stringent quality checking and rigorous product standardization at the national level. It’s also imperative to seek ways of improving performance of such cements.
Description: A thesis submitted to the School of Graduate Studies of Addis Ababa University in partial fulfillment of the requirements for the Degree of Master of Science in Construction Technology and Management
URI: http://hdl.handle.net/123456789/1578
Appears in:Thesis - Constructional Technology & Management

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