Sand replacement test also called as a Field Density Test. This experiment is doing to find out the density of compacted soil whether the compaction has done as per the requirement or not.
Density / Unit Weight
Unit weight of the material is simply defined as Mass per Volume (M/V) and also it is called as Unit Weight of material. For better understanding, If a Steel weight 100 Kg (M) then the steel was immersed in water & weighed again (V). Another name of unit weight is called Density.
Density = M/V
Why Sand is used for the Sand replacement Test?
In dry condition, the sand will be flowing free when compressed it could not change its density. If we may try to use other loose soil it could not have defined density value so the experiment will go wrong.
Sand Replacement Test
As above said, the core test method is not possible to find the density of cohesionless soil. So the sand replacement test has used to find out the density of the compacted soil.
- Sand pouring cylinder
- Weighing Machine
- Metal Tray with Central hole
- Trowel for dig the soil
- Calibration can
Calibration of Apparatus
- The sand pouring cylinder should be free from dust then the dry sand should be poured up to the top of cylinder & note the weight as W1.
- Then the cylinder should be on the cone and open the slit. Now the sand will freely flow on the conical pot up to fill fully. Now weight the conical sand and note it as W2.
- Now fill the conical portion by the sand into the cylinder now weigh (W3) again it should be equal to the W1.
- Now do it again & the calibration of apparatus over.
- At first, weight the sand pouring cylinder with sand and note the weight as W1.
- The ground surface should be level & clean where the test is going to be conduct.
- Place the metal tray onto the ground surface. Now excavate the soil through the hole up to 12cm to 15cm and collect the soil on the metal tray.
- Now weight the excavated soil and note it as Wh.
- Calculate the moisture content of soil from lab.
- Now place the sand pouring cylinder on the soil excavated area and open the slit for flowing the sand into the digged area up to fill fully.
- Then weight the Sand pouring cylinder with the balance sand (W4).
- Do the test at least for 3 different location to find out the density of compaction.