Bulking of Sand Test

“Understanding Bulking of Sand: Test, Causes, and Implications for Construction”

What Is Bulking of Sand?

Bulking of Sand occurs when sand comes in contact with moisture, which forms a thin layer of water around the sand particle and this thin layer of water exert an outward force on each other which cause the sand particle to move away from each other and ultimately increase the volume of sand.

This phenomenon of the increasing volume of sand due to moisture in the sand is called “Sand Bulking “

Bulked Sand
"Understanding Bulking of Sand: Test, Causes, and Implications for Construction" 7

Excessive moisture or bulking affects the water-cement ratio and ultimately reduces the strength and durability of concrete.

bulking of sand is code: IS 2386-3 if the sand contains 4% moisture, then it will increase sand volume by 25%.

Bulked sand consumes more volume & hence if volumetric measuring is done while proportioning for concrete, bulking correction is necessary.

Moisture Content in SandIncrease in Volume of Sand
Bulking of Sand
"Understanding Bulking of Sand: Test, Causes, and Implications for Construction" 8

Bulking depends on sand particles’ size. As the smaller the particle size of sand, the volume of bulking increases. Generally, Medium and coarse sand have lower bulking sand.

High bulking result in low quality concrete mix and ultimately reduce the strength of concrete.

Principle of Bulking of Sand

Bulking of a sand test depends on the fact that the dry volume of sand and saturated volume of sand has almost the same volume.

Therefore in this test sand is filled in a container and water is added to it up to its saturation point. As the sand is saturated in water its volume is reduced and shows the actual volume of sand or dry volume of sand.

By measuring the difference between the volume of sand and saturated volume of sand we can calculate the bulking of sand value.

Bulking of Sand Significance 

In simple words, it is often said that sand bulking is just the looseness of soil without compacting. Generally, water available in any sand reduces the pores in the sand and compacts the sand.

Sand is employed in concrete for the reduction of segregation and to fill out the pores between cement and coarse aggregates.

for instance, we’d like 1 m3 of sand in concrete, we’d like to understand the approximate sand bulkage value.

If the given sample features a bulkage of 25% then we’d like to require 25% more sand or 1.25 times of the sand while volume batching to urge 1 m3 of sand for concrete.

bulking of sand graph
"Understanding Bulking of Sand: Test, Causes, and Implications for Construction" 9

If we don’t take this extra amount of sand considering the bulkage value, the entire volume is going to be lessened to 75% after adding water.

we all know that the standard of concrete depends tons on the right proportioning of the contents.

Generally, we consider the wet volume of concrete is 1.5 times the quantity of dry concrete, during this case, we are typically using approximately 30% of sand bulkage and 20% of wastage.

If we don’t consider the bulkage of sand, the entire quantity is going to be lessened and can impact the general concrete quality.

Bulking of Sand Test Procedure

The sand is filled, in the loose condition in a box of measured height (H) in cm.

The box is then filled with water and rodding is done to make the sand settle and consolidate.

Care should be taken that the sand does not overflow during the flooding and compaction.

The sand is then leveled in the box and the drop in height is measured (h) in cm.

Bulking of sand is calculated as,

Bulking of Sand test
"Understanding Bulking of Sand: Test, Causes, and Implications for Construction" 10

Dry sand occupies the same volumes as fully saturated sand. The bulking may differ from load to load and day to day depending on the surface moisture content and fineness of sand.

Therefore, it becomes essential to make bulking corrections by checking the actual bulking of sand proposed to be used by volumetric batching for mortar or concrete.

Sample Calculation

H = 10 cm (Height of Bulked Sand in Container)

h= 2 cm (Height Difference of Saturated Sand & Bulked Sand in Container)

Bulking of Sand (%) = (h/H) x 100

= (2 / 10) x 100

= 20 %

Video: Sand Bulking Determination


In conclusion, bulking of sand it means the volume of sand increases when it becomes moist, this increase the volume of sand due to the formation of water films around the sand particles, and it causing them to separate and occupy more space.

Bulking can have significant implications in construction projects, as inaccurate estimation of sand volume can lead to material wastage or insufficient supply.

The degree of bulking in sand is influenced by factors such as moisture content, particle size, fine sand and shape tends to experience greater bulking than coarse sand, while rounded grains have higher bulking potential compared to angular grains.

Understanding and managing bulking is crucial for accurate material calculation and efficient resource utilization in construction projects, by considering the moisture content and sand characteristics, can make precise estimation of the required sand volume.

Proper management of bulking ensure cost effective construction practices and contributes to the successful completion of project while minimizing material waste.

To account for bulking, engineers and construction professionals employ techniques such as determining the bulking factor, which is the ratio of the volume of damp sand to its dry volume.


What is bulking of sand?

Bulking of sand refers to the increase in the volume of sand due to the presence of moisture. When water is added to dry sand, the sand particles tend to absorb water and create a film around them, leading to an increase in the overall volume of the sand.

Why does bulking of sand occur?

Bulking of sand occurs because of the surface tension between water and the sand particles. The water forms a thin film around the particles, causing them to separate and occupy more space, resulting in an apparent increase in the volume of the sand.

Why is the bulking of sand important?

Understanding the bulking of sand is crucial in construction and engineering fields. It affects the accuracy of measurements and calculations related to the quantity of sand required for various applications, such as concrete mix design and backfilling.

How is the bulking of sand determined?

The bulking of sand is determined by performing a bulking of sand test. In this test, a known volume of dry sand is measured and then the sand is thoroughly wetted with a known quantity of water. The increase in volume after wetting is measured, and the bulking factor is calculated.

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