Theory

The object of this test is to determine dry density of natural or compact soil by the sand replacement method. Unit weight is the weight of soil unit. Volume is called unit weight or density, it includes the whole soil mass i.e. the solid particles plus all void with or without moisture its depends upon voids ratio ‘e’ degree of saturation ‘s’ since the dry unit weights of solid per unit of total volume of a soil mass is called dry unit.

Application

The density of soil affects most of the properties of soil. Density of soil-in-place is compacted soil and used as quality control measure of earth work in embankment in place soil density of natural soil helps to determine bearing capacity, calculation of settlement as well as for stability analysis of natural slopes.


Item required

Sand pouring cylinder, calibrating container, balance 2 nos. one of 10 kg capacity sensitive to 1.9 and another of 1 kg capacity and accurate to 0.19 , sieves 1.00 mm and 600 microns is sieve metal container with cover tray with hole, excavating tools, oven, natural sand, circular templates 200 mm diameter with a central hole of 100 mm diameter.


Diagram


Sand pouring cylinder, calibrating container, metal container with cover tray with hole


Procedure


Calibration of apparatus


a)  Determination of the mass of sand in the cone


1)  First prepared of sand passed through 1mm and retained on 600 micron I.S. sieve by sieving, drying and removing organic matter etc.

2)   Filled the sand pouring cylinder (SPC) with sand upto 10mm from the top weighted it with lid (M1)


3)  The calibrating container was kept in a clean tray and placed the SPC on the top of the container so that the flanges coincided with each other.

4)   The sand started to flow into the container after opened the shutter.


5) The shutter closed when no further movement of the sand take place. Lift the cylinder gently and weighted in with lid (M3)

6)   Collected sand in the tray, the sand above the calibrating container by moving a straight edge on the flange of the container. This was the sand that had filled the cone of SPC weighted it to the nearest gram.


7) The steps 2 to 6 repeated three times and determined the mean weight (M2) of the sand in the cone of the pouring cylinder.

b)  Determination of bulk density of the sand

8) The internal diameter and depth of the calibrating container at three different placed and taken the mean calculated. The mean volume of the calibrating container (V)

9) From the weight M1 M2 and M3 calculated the mass of the sand in the container (M1 -  M2 - M3)

10) Calculate the bulk density of sand.



c)   Measurement of bulk density of the soil-in-place


11) Cleaned, scraped and marked level 450mm square surface using a template and chalk powder marked the position of the hole and the flange of the cylinder on the leveled surface on the soil.

12) Kept the metal dry so that the hole of the tray co inside with marked position of the hole.


13)Collected the soil so executed into a metal container the depth of the hole was measured with steel rule, so that it does not exceed 150mm.

14)All the loosed soil in the hole was collected in the metal container.


15) Removed the tray and place the sand P.C. filled with sand to constant weight (M1) on the hole.

16)  Opened the shutter and allowed the sand to run into the hole, closed the shutter when the movement of the sand stopped and removed the SPC and weighted it (M4)


17)  Marked at least 3 holes to get mean value of the density of soil in place.


d) Determination of dry density


18)  Determined the moisture content of the collected soil.

19)   Calculated dry density from bulk density and the moisture content.



Observation


A) CALIBRATION


SR.NO.
PARTICULARS
DETERMINATION NO.
MEAN
01
Mass of cylinder + sand before (M1) in gms
6150.00 gms

02
Mass of sand in the cone of pouring in cylinder
380 gms

03
Mass of cylinder + sand after pouring (M3) in gms
5715 gms

04
Mass of sand + fill calibrating Ma = (M1 – M3 – M2) in gm
45 gms

05
Volume of calibrating containers
1)     Dia. In mm
2)   Depth in mm
3)   Volume in mm
1178.09 cm3

06
Bulk density of sand
Is = (Ma)/V   gm/cm3
0.0382 gm/cm3




B) BULK DENSITY


SR.NO.
PARTICULARS
HOLES
REMARK
01
Mass of wet soil from hole (mw) in gms
2400 gms


9.94X10-4 gm/cm3
02
Mass of cylinder + sand before pouring (M1) in gms
6150 gms
03
Mass of cylinder + sand after pouring in the hole (M4) in gm
4030 gms

04
Mass of sand in the hole
Mb = (M1-M4-M2) in gms
1730 gms
05
Bulk density of soil
Tb = Mw/Mb X Vs     gm/cm3
0.0529 gm/cc


Water content = 13.63 %


RESULT

1)    The dry density of soil = 0.388 gm/ml
2)   The bulk density of soil = 0.0529 gm/ml
3)   Water content w = 13.63 %
4)   Dry unit of soil = 3.8062 gm/ml