Hey, Guys welcome to we civil engineers.
In this video, we will discuss the phenomenon
of the bulking of sand.
So, let's get started.
What is bulking of sand?
Bulking of fine aggregate or sand is the phenomenon
of increase in sand volume due to the increase
of moisture content.
Increase in sand volume due to the increase
in moisture content.
Causes of Bulking of Sand
When water is added to sand, a thin film of
water is formed around the sand particles.
the film exerts surface tension on particles,
making them move apart.
This leads to an increase in volume because
there is no direct contact among particles.
So, if you observe here, When the water is
added to sand, sand particles move like this,
like there will some gap between the sand
particles.
This causes the volume of the sand to increase.
Factor affecting the bulking of sand.
There are 2 major factors which affect the
bulking of sand.
1. The fineness of the aggregates
2. Percentage of moisture content
If you see in the picture; the bulking of
the sand increases with the increase in moisture
content.
This happens up to a limit beyond which any
moisture addition will decrease the volume.
The volume increases with an increase in moisture
content.
The volume may increase up to 20 to 40% when
the moisture content is 5 to 10 %.
If you see in the picture: we have observed
bulking of sand in the different sands.
I.e., Fine sand, medium sand & coarse sand
& the bulkage of fine sand is higher than
the medium sand & coarse sand.
This is because fine-grained sands have higher
voids than medium and coarse-grained sands.
Hence, the percentage of moisture absorbed
and the percentage volume increase is the
highest.
If the effect of bulking is not studied properly,
the concrete designed will have an insufficient
amount of sand resulting in a harsh mix.
Bulking of sand will affect the yield of concrete
for a given cement content.
