Field density by sand replacement method

Dnyan Deshmukh

Staff member
Field density by sand replacement method

Ref : IS 2720 (part 28)

Purpose : To determine the field density of soils containing coarse grained particles.

Apparatus :

Sand pouring cylinder

Metal tray with hole

Tools for leveling and excavating

Container

Calibrating container

Plane surface ie a glass of Perspex plate

Balance

Sand - Dry and clean test sand of uniform gradation, passing through 1.0mm and retained on 0.6mm

Test Procedure:

Clean and dry test sand passing through 1.0mm IS sieve and retained on 0.6mm IS sieve is collected in sufficient quantity (about 15 Kg)

Remove the top cap of sand pouring cylinder and close the shutter

Fill the cylinder with dry test sand up to about 10mm from the top and the cap is replaced

Weight of the cylinder with the sand is determined W1 gm

Place the sand pouring cylinder over the calibration cylinder, open the shutter and allow the sand to flow into the calibration cylinder and close the shutter

Place the sand pouring cylinder on a clean plane surface (glass or Perspex plate)

Open the shutter and keep it open till the sand fill up core fully and there is no visible moment of sand as seen from the top of the cylinder by removing the cap

Close the shutter remove the cylinder

Weigh sand which occupied the cone (W2 gm)

Refill the sand pouring cylinder find the weight w1 gm

Place the cylinder centrally on top of the calibrating container and open the shutter

When the sand fills up the calibrating container and cone completely and there is no movement of sand, close the shutter

Find the weight of sand pouring cylinder and remaining sand (W3 gm)

Repeat the above procedure 3 times and determine the mean values of W2 and W3

Find the weight of the sand required to fill the calibrating container up to the top level

Find the volume of the calibrating container (v) measuring the internal dimensions (diameter and weight) or by filling with water and weighing

From the weight of the sand Wa and its volume V in the calibrating container determine the density of sand

Measurement of filed density:

The site where the field density is to be conducted is cleaned and leveled using a scraper for an area of about 450mm2

The metal tray with central hole is placed on the prepared surface

Using this central hole as pattern the soil/material is excavated using a trowel up to a depth of 150mm

Remove the loose material and collect it carefully in a metal container

Find the weight of metal container with soil W gm

The sand pouring cylinder is refilled with sand such that its weight W1 gm

The metal tray with central hole is removed and the sand pouring cylinder is placed centrally over the excavated hole

The shutter is opened till the sand fills the excavated hole and the cone completely and there is no further movement of sand in the cylinder

The shutter is closed and the cylinder is weighed W4 gm

Find the weight of sand filling the excavated hole alone Wb

Find the moisture content of the soil
 

Attachments

  • C4M Field Density by Sand Replacement Method.docx
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Reading through the test procedure, it sounds very similar to what I know to be called a "Sand Cone Test." It is a very reliable means of compaction testing, particularly when the Engineer does not have access to a nuclear gauge. A drawback to this method of testing is that you need to be able to dry the in situ sample, which can add a time duration to receiving test results - If your Contractor is in production and wants to continue compacting materials, you need to account for the time lapse required to ascertain the test results.

I thought I'd clip in a video comparison that might be of help to the Membership on this topic.