Preparation of Ethiopian Standard Sand for The Purpose of Construction and Testing
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Date
2005-09
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Addis Ababa University
Abstract
Sand is a naturally produced material resulting from the
mechanical and chemical breakdown of rocks. Sand is the most common
and loosely packed mineral on the earth's surface. Sand particles mostly
range from 0.02 mm to 2.00 mm in diameter. Silica sand is the term
used to describe sand that has a very high percentage of silicon dioxide
(SiO2).
In the field of civil engineering, silica sand is used for several
purposes like, in construction, in industries for the production of
different construction materials. Sand, which is graded according to a
specified standard, is used for testing of Portland cement and concrete,
in field density determination using sand replacement method, and in
water and sewage treatment plants as a filter media.
Due to lack of standard silica sand in Ethiopia, the country is
losing high foreign currency by importing standard silica sand from
abroad. The purpose of this research is the identification of the different
sources of sand in different parts of the country for the purpose of
standard sand production.
To achieve the research objective, sand samples for laboratory
investigation and field test were collected from North Showa (Jema river
valley) and Dire Dawa town.
Visual inspection, index property tests, test for impurities and
chemical contents were conducted on both samples. Sand replacement
and mortar test were done to check the applicability of the local samples
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in field density determination and in testing of Portland cement
respectively.
Grain size analysis and impurity test results revealed that both
local sand samples cannot be used as standard sand as they are
collected directly from their natural places. Thus, inorder to be used as
standard sands both samples must be washed, oven dried, sieved and
separated to various size fractions and mix each fraction according to
the grading requirement.
In all of the test results, the compressive and flexural strength of
mortar cubes made with local samples gave lower values compared to
that of imported sand. However, a relatively uniform trend was
observed both in the compressive and flexural test results between the
local samples and the imported one.
The field density test by sand replacement method showed that,
both local sand samples gave the same result with the imported Ottawa
standard sand in almost all test locations irrespective of the silica
content.
Laboratory and field tests conducted on both local sand samples
showed that there is a high possibility that both local sand samples can
replace the imported standard sand.
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Keywords
Construction