In many cases it is necessary to know the wet/dry density of the soil in the field, especially before planning activities such as compaction. This becomes especially important such as the construction of earthen dams, embankments, etc., to control field compaction, i.e. to know how close the field values ​​are to the laboratory values. ?d max And OMC, This information is important because the Earth’s structure is designed based on properties such as the shear strength of laboratory-deposited soils.

Method-1 [The Core Cutter Method]

Fig-1 Clay Core Cutter Test
Fig-1 Clay Core Cutter Test

This is a simple and straightforward method for determining area density.

The tool consists of a cutter, dolly and rammer (Figure 1) The weight and dimensions of the cutter should be noted before testing. With the collar mounted on top, the cutter is driven down by a weight falling on a wooden cushion (dolly) placed over the collar.

When driving is complete, the soil on the side is removed with a hoe. The cutter along with the soil is cut at the base and brought out. The collar is removed and the soil protruding at the ends is cut. The cutter with the clay is now weighed so that the difference with the empty weight gives the wet weight of the sample which when divided by the volume gives the wet density. The soil sample is removed from the cutter and samples are taken for determination of woo, From ?Wet And woo We calculate the dry density.

This method is not suitable for dry sand because it cannot be held in the cutter while lifting, apart from vibration-induced compaction resulting from the load falling on the dolly, which affects the natural density.

Also read: Soil Core Cutter Testing [Step-by-Step Guide]

Method-2 [The Sand Replacement Method]

Keeping a rimmed pan with a central hole of dia. 100 mm on the ground A cylindrical hole is excavated, from which the soil in the hole is carefully collected and placed in a pan (Figure-2a) The weight of the soil is determined. The samples from the soil thus collected are used to determine woo,

Fig-2 Sand replacement test of clay
Fig-2 Sand replacement test of clay

To get the area (wet) density we need to determine the volume of the hole who does the rest.

It uses a device in the form of a cylinder pouring sand with a calibrating can (fig-2b) The volume of the cylindrical mold can be determined by measurement. The can is usually of a lamp. 100 mm and its depth is assumed to be the same as the depth of the hole dug in the soil. The sand pouring cylinder has a conical (upright) funnel-like (inverted) part at the bottom with a stopper at the junction of the bottom that allows/stops the flow of sand from the cylinder.

The sand pouring cylinder is filled with almost dry uniform sand (size within 600 – 300 µm category). To determine the bulk unit weight of sand, the can is placed at the bottom of the cylinder and the sand is allowed to flow down, filling the can and the conical portion. More sand than is needed to fill the can is removed by running a scale or spatula horizontally across the top of the can. Its unit weight can be obtained from the weight and volume of sand filling.

Our next attempt is to determine the weight of the sand filling the excavation hole so that dividing this by the unit weight of the sand gives us the volume of the hole.

For this we have to first find the weight of sand filling the conical part. For this we weigh the cylinder with sand and keep it on a flat surface (fig-2c) we drive sand to fill the cone, close and weigh the cylinder again. The difference gives the weight of the sand filling the cone.

At the final stage of work, we weigh the cylinder approximately filled with sand and bring it over the cylindrical hole dug in the ground and empty it until it fills the hole and the conical part (fig-2d) Now close the stopper and lift the weight. The difference in weight gives the weight of the sand filling the cylindrical hole and the cone. This is subtracted from the weight of the sand filling the pre-determined cone which gives us the weight of the sand filling the hole alone. Dividing this by the unit weight of sand gives the volume of the excavated cylinder. Know Weight And volume From the excavated soil thus obtained, we can determine that field density, and by the amount of water, dry density,

Read also: Soil sand replacement test [Step-by-Step Guide]

article written by

Dr. Nain P. Kurien

Er. Mukesh Kumar

Photo of author
Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.