Moisture present in fine aggregate causes, it’s volume increases, this phenomenon is known is bulking of sand. It is very simple to know what is bulking of sand.
The bulking of sand is caused due to the fact that moisture causes layer or film of water around sand particle formed which results in the increase of volume of sand. The volume of sand may increase up to 20 to 40% when the moisture content is 5% to 8%.
It’s actually due to thin film of water around the sand grains and interlocking of air in between the sand grains and film of water. The finer the sand, the more will be the increase in the volume of the given moisture contain.
How to determine bulking of sand in field ?
Apparatus required to calculate bulking of sand
- Measuring Cylinder
- Steel Rod
- Soil Sample
- Small Container
Procedure to Calculate the percentage step by step.
- At first, fill the sample of sand in a cylinder up to the height of about 200 ml accurately.
- We should not compact the soil sample while filling into the cylinder and can be taken the help if measuring rod or tape to measure the accurate level of the sand sample.
- After that transfer the soil sample into another cylindrical pot or container.
- Again the cylinder is filled with water up to height 100ml and the sand sample is refilled with continuous stirring with the help of a stick or steel rod.
- Leave it for some time to get settle all particles of the sand sample below the bottom of the container.
- After some time the level of sand will be below the 200ml and let the present level be “x”
- This process is repeated three to four times whose average value will give the percentage of bulking of sand for the required sample of sand.
What is its significance?
Bulking of the sand show the false volume of the actual sand sample. when we have to prepare concrete then we have to provide the proportion of mix according to the design of the engineer.
So, if we don’t have knowledge about what is bulking of sand we couldn’t find out the actual amount of fine aggregate or sand required to prepare the required amount of concrete which makes the work slow as well as uneconomical.
It also affects when we are mixing cement with sand. If sand is bulked then cement will not be mixed with sand thoroughly which results in the weak form of concrete and so as the structure.
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