MITIGATING THE EFFECT OF CLAY CONTENT OF SAND
ON CONCRETE STRENGTH
31st Our World in Concrete and Structures (OWICs) - 2006
L. M. Olanitori*, Federal University of Technology, Akure, Nigeria
Silt, Clay, Concrete, San, Cement
In the present day construction industry in Nigeria, concrete has emerged as the
most common building material. Hence careful consideration must be given to
factors that affect its strength. For sand having above 3.4% of clay content used in a
1: 2: 4 mix of concrete, resulted in the production of concrete with compressive
strength less than 21N/mm2 (1) This work determines the amount of cement needed
for sand samples with varying amount of clay/silt content from 0% to 10%, to
produce concrete with compressive strength not less than 20N/mm2 for mix 1: 2: 4.
A sample of sand was sourced from a location in Akure metropolis of Ondo Sate.
The sand sample was divided into two parts. First part of the sand sample was
washed free of clay and slit and sun dried, while clay and silt were sieved out of the
second part using 0.150mm sieve. The washed sand sample was divided into 10
parts in such a manner that from each part, at least 10 cubes of 150 x 150 x 150 cm3
can be made.
The sieved clay/silt is added to each of the parts of the washed sand from1% to 10%
by weight of the sand. The amount of cement necessary to be added to each part of
sand with varying content of clay/silt from 1% to 10%, so as to achieve minimum
strength of 20N/mm2 for mix ratio 1:2:4 were determined. It was discovered that the
higher the clay/silt content, the higher the amount of cement needed to achieve the