Bulking of Sand

Determination of Bulking of Fine Aggregate

Objective : To determine bulking of a given sample of fine aggregate.

Reference : IS : 2386 ( Part III ) - 1963

Theory :

Free moisture forms a film around each particle. This film of moisture exerts what is known as surface tension which keeps the neighbouring particles away from it. Similarly, the force exerted by surface tension keeps every particle away from each other. Therefore, no point contact is possible between the particles. This causes bulking of the volume. It is interesting to note that the bulking increases with the increase in moisture content upto a certain limit and beyond that the further increase in the moisture content results in the decrease in the volume and at a moisture content representing saturation point, the fine aggregate shows no bulking.

Apparatus : Measuring jar, Taping rod etc.

Procedure :

1. Put sufficient quantity of the sand loosely into a container. Level off the top of the sand and pushing a steel rule vertically down through the sand at the middle to the bottom, measure the height. Suppose this is h1 cm.

2. Empty the sand out of the container into another container where none of it will be lost. Half fill the first container with water. Put back about half the sand and rod it with a steel rod, about 6 mm in diameter, so that its volume is reduced to a minimum. Then add the remainder of the sand and rod it in the same way.

3. The percentage of bulking of the sand due to moisture shall be calculated from the formula:

 

                                                                                                   

Conclusion / Result : Bulking of a given sample of fine aggregate is found to be ……. %