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
