Characterization and Optimization of Volcanic Ash and Portland Cement blend for Property Enhancement of Concrete
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Date
2018-11
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Addis Ababa University
Abstract
Volcanic Ash is one of naturally occurring Pozzolanaic material that was tested in this research work for partial replacement of cement for production of concrete. With respect to reduction of cement consumption for sustainable construction (i.e. reducing GHG emission) evaluation of the strength reduction is crucial as it has a severe impact on the structure under construction. This paper examines the effects of replacing cement by using Lege-Dadi Volcanic Ash on the strength and certain durability characteristics of concrete. The research aims to determine the optimal amount of Volcanic Ash for production of high-grade concrete. Preliminary tests of the different properties of materials used for this research were carried out. The Lege Dadi Volcanic Ash satisfied the requirement of ASTM C618-00.The samples of Volcanic Ash were prepared in five different proportions (0, 5, 10, 15 & 20 wt %) and design mix ratio of 1: 2.9: 3.9 with a 0.61 w/c ratio to make 45 cubic and 27 cylindrical concrete samples. The cubic samples were used to assess compressive strength tests where as the cylindrical samples were used to determine abrasion resistance, water absorbency and acid attack tests. Uniaxial compressive tests were used to examine the strength of concrete achieved after 3, 7 and 28 days of curing. Result of compressive strength show that early strength of concrete samples were low, but as the curing period increases their compressive strength increases.15 % replacement of Volcanic ash was an optimum replacement in this research with compressive strength of 21.3 MPa less than by 4 % with the control (i.e. 0% of Volcanic Ash)and expected to increase in subsequent curing days. The permeability of cylindrical concrete samples decreases as the percentage of volcanic ash in the mix increases, the weight loss due to abrasive force of samples containing volcanic ash were not considered as significant. Acid significantly attacks the surface texture of both control and Volcanic Ash sample concrete cylinders. However, after 28 days of immersion samples contain Volcanic Ash powder reduces the mass loss, compared to the reference control concrete samples.
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Pozzolanic materials, Compressive strength, Concrete mix ratio, water to Cement ratio