STANDARD
- IS: 2720 (Part 28) 1974.
OBJECTJVE
- To determine the in place dry density of natural or compacted fine ,medium & coarse grained soils by sand replacement method.
APPARTUS
- Large sand pouring cylinder for depth more than 150mm and not exceeding 250mm.
- Tools for excavating holes such as a scraper tool for leveling the surface, bent spoon or dibber for digging holes.
- Cylindrical calibrating container with material diameter of 200mm and an internal depth of 250mm.
- Balance of capacity 15kg and sensitivity l gram.
- A glass plate or other plane surface about 600mm square and 10mm thick or larger.
- Metal containers.
- Metal tray 450mm square and 50mm deep with a 250mm hole in the center.
- 1mm and 600nicrons IS sieves.
- Clean, uniformly graded natural sand passing 1mm sieve and retained on 600 microns sieve.
PROCEDURE
Calibration of Sand Pouring Cylinder
- Clean and dry, sand passing 1mm sieve and retained on ó00microns sieve 23 to 24 kg of sand for large pouring cylinder.
- Remove the cap of the pouring cylinder.
- Weigh the empty pouring cylinder (W).
- Close the shutter of the cone.
- Fill the sand in to the pouring cylinder about 10mm below from the top.
- Determine the net weight of sand in the cylinder (W1).
- Now place the pouting cylinder on a clean plane surface, open the shutter and allow the sand to flow in to the cone.
- Close the shutter when the flow stops.
- Carefully collect and weigh (W2) the sand discharged from the pouring cylinder.
- Refill the pouring cylinder with sand such that the initial weight is WI.
- Place the pouring cylinder on the top of the calibration cylinder concentrically.
- Open the shutter and allow the sand to flow in to the calibrating cylinder.
- Close the shutter when the flow stops or no further movement of sand takes place in the cylinder.
- Determine the weight (W3) of the pouring cylinder.
- Repeat the above procedure for at least three times and determine the mean values of W2 and W3.
- Determine the volume (V) of the calibrating cylinder either by measuring the dimensions (Diameter and height) or by filling with water until the brim.
CALCULATIONS
- Weight of sand (Ws) in the calibration container up to level top
Ws=W1-W3–W2grams
Volume of calibrating container = V cc
Bulk density of sand (Is) =Ws / V gm/cc.
Determination of Soil Density
- Prepare a flat area approximately 60 Sqcm square by trimming preferably with the aid of a scraper
- Place the metal tray with central hole on the prepared surface of the soil to be tested.
- Excavate the hole in the soil with a dibber using the hole in the tray as a pattern to the depth of the layer to be tested.
- Carefully collect the excavated soil from the hole and weigh (Ww).
- Determine the water content (W) of the excavated soil as per IS: 2720 (Part 2)1973.
- Fill the pouring cylinder to the constant weight (W1) i.e. weight equal to the initial weight during calibration.
- Remove the metal tray before the pouring cylinder is placed in position over the excavated hole.
- Place the cylinder such that the base of the cylinder covers the hole concentrically.
- Open the shutter and allow the sand to run out in to the hole.
- Close the shutter of the pouring cylinder when no further movement of sand takes place in the cylinder.
- Remove the cylinder and determine the net weight of sand (W4).
CALCULATIONS
- Calculate the weight of sand (Wb) required to fill the excavated hole from the equation
Wb=Wl-W4-W2
W1=Weight of sand in the cylinder before pouring in to the hole.
W2= Mean weight of sand in the cone.
W4=Weight of sand in the cylinder after pouring in to the hole.
Bulk density,(Yb)= ( Ww/Wb ) x Ys gm/cc
Ww=Weight of soil excavated.
Wb=Weight of sand required to fill the hole.
Ys=Bulk density of sand.
Dry density,(Yd)= Yb/ (1+ W/100) gm/cc
Yb=Bulk density.
W=Moisture content of soil in percent.
REPORT
- Report the bulk density and dry density of soil to the nearest second decimal.
PRECAUTIONS
- Care shall be taken to see that the test sand used is clean, dry and uniformly graded.
- Care shall be taken in excavating the hole to see that the hole is not enlarged by levering the dibber against the side of the hole, as this will result in lower densities.
- Care shall be taken to see that the same initial weight of sand is taken during calibration and during density measurement in the field.
CALIBRATION OF SAND POURING CYLINDER
IS :2720 (Part 28) 1974
| Description | Units | Test I | Test 2 | Average |
| Initial weight of sand in the cylinder (W1) | gms | |||
| Weight of sand in the cone (W2) | gms | |||
| Weight of sand in the cylinder after pouring in to calibrating container (W3) | gms | |||
| Weight of sand in the calibrating container up to level top (Ws) W1-W3-W2 | gms | |||
| Volume of calibrating container (V) | cc | |||
| Bulk density Ys =Ws / V | gms/cc | |||
| Remarks: | ||||
DETERMINATION OF DRY DENSITY OF SOILS IN PLACE (SAND REPLACEMENT METHOD) IS:2720 (Part 28)1974
Wt. of sand in cone ( W2) : Bulk density of sand :
| Description | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 | Test 6 |
| Representing test chainage | ||||||
| Offsets from center line (m) | ||||||
| Depth of the hole | ||||||
| Weight of material from hole ( Ww) gms | ||||||
| Weight of sand + cylinder before pouring ( W1 ) gms | ||||||
| Weight of sand + cylinder after pouring (W4) gms | ||||||
| Weight of sand in hole Wb=WI-W4-W2 | ||||||
| Bulk density of materials y b=(Ww/Wb)x rs gm/cc | ||||||
| Moisture meter reading in % | ||||||
| Corrected moisture content/Moisture content (drying) | ||||||
| Field Dry Density y d= Yb / ( 1+W/100 ) | ||||||
| %Compaction obtained | ||||||
| Average Compaction obtained (%) : Standard Deviation:
Required Compaction (%): Mean Density: Density acceptance criteria check: |
||||||