Comparison of Concrete Properties Produced Using Mugher, Messebo and Diredawa Cements.

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Date

2005-11

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Addis Ababa University

Abstract

Properties of concrete and its constituent materials are theoretically explained. The three cement factories across the country were visited and test results of Mugher OPC and PPC, Messebo OPC and PPC and Diredawa PPC were collected from their respective factories. Then the chemical and physical properties of these cements were analyzed. Furthermore, three mix proportions for Normal, Intermediate and High Strength Concretes were conducted in laboratory. At each mix proportion there are five mixes which were made keeping every condition the same but varying the cement types. To see the effect of curing on strength development among concretes made of the five cement types, different curing conditions were applied. The analyzed cement test results together with literature survey on effect of cement in concrete properties are used to propose and compare concrete strength and other properties among the concretes made of the five cements. The laboratory conducted compressive strength test results are also used to compare the rate of strength development, the difference in compressive strength values with age and to see the effect of curing on compressive strength development. In each class of concrete, concreting was made keeping every condition the same except varying the cement type; hence, the variation on the concrete properties is mainly attributable to the cement’s properties. As shown on the analysis part, the expected concrete strength proposed using the cement test results analysis has turned out to be similar with the laboratory compressive strength test results. In fact, this has created strong confidence with regard to the other concrete properties proposed using the cement test results analysis. Observation on the test results of this research indicates that for the mix proportions and curing conditions made in this study, at all ages and classes of concrete, Messebo OPC has produced the highest compressive strength concrete, followed by Mugher OPC, Messebo PPC, Mugher PPC and Diredawa PPC in descending order. Besides, though the compressive strength differences between the concretes made of the PPCs and OPCs show a decreasing trend with age, the gap in V strength at the age of 91 days between them is too large to be narrowed and matched with time. Therefore, the PPCs can not produce a concrete strength as high as that of the OPCs. The low pozzolanicity of the volcanic pozzolanas used in production of the three PPCs as well as shortage of extended moist curing are the reasons believed to make the ultimate strength of concretes made of the PPCs to be lower than that of the OPCs’ at the age of three months.

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Diredawa Cements

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