Comparison of Concrete Durability As Produced by Various Cements Manufactured in Ethiopia
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Date
2007-02
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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.
Key words: Hydration, Permeability, Diffusion, Sorption, Porosity, Resistivity
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Keywords
Hydration, Permeability, Diffusion, Sorption, Porosity, Resistivity