The Use of Manufactured Sand in Concrete Production Test Results and Cost Comparison
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Date
2006-07
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Addis Ababa University
Abstract
Manufactured sand is a term used for aggregate materials less than 4.75mm and which are
processed from crushed rock or gravel. Due to booming of construction activities in our
country, natural sand resources are increasingly depleted and its cost is becoming increasingly
high. This research was, therefore, conducted to study the influence that manufactured sand
have in compressive strength of concrete, to compare the cost of different mix compositions
and to assess the prospects of using manufactured sand as replacement of natural sand in
Ethiopia.
Initially, different natural and manufactured sand samples to be used in the concrete mixes
were collected and their physical properties were studied. Fifteen different concrete mixes
having five mix proportions for both natural and manufactured sand (i.e. 100%NS+ 0%MS;
75%NS+25%MS; 50%NS+50%MS; 25%NS+75%MS and 0%Ns+100%MS) were prepared
for normal strength, intermediate strength and high strength concrete using a water cement
ratio and cement contents of 0.54, 370kg/m3; 0.39, 460kg/m3; 0.30, 520kg/m3 respectively.
The properties of these mixes have then been assessed both at the fresh and hardened state. In
addition, comparison of costs for each concrete mixes based on the price of the concrete
material collected from Addis Ababa, Nazareth, Awassa, Mekelle and Jimma towns were
made.
The results of the hardened properties of the mixes have shown that concrete mixes with
partial proportions of manufactured and natural sand achieved a higher compressive strength
at all test ages. The cost comparisons results also have shown that using manufactured sand in
partial or full replacement to natural sand doesn’t cause any significant cost variation. It has
been found also that use of manufactured sand is more suitable for high strength concrete
production. It can therefore, be concluded from the findings of this research that when the
availability of natural sand is scarce or in cities where the price of natural sand is as expensive
as manufactured one, manufactured sand concrete mix is a viable and better alternative to the
use of natural sand.
Keywords: aggregate, compressive strength, concrete, cost, manufactured sand, workability.
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Keywords
Aggregate; Compressive Strength; Concrete; Cost; Manufactured Sand; Workability