Soil Mechanics Lab Soil Mechanics Lab CE350CE350 Field DensityField Density 11

Experiment No. 4 Experiment No. 4 Field DensityField Density

(Sand Cone Method)(Sand Cone Method)ASTM D 1556/02ASTM D 1556/02

Soil Mechanics Lab Soil Mechanics Lab CE350CE350 Field DensityField Density 22

Direct GoalDirect GoalQuality control for CompactionQuality control for Compaction

compacted ground

d,field = M/V

wfield = ?

Compaction specifications

Compare!

w

d

Soil Mechanics Lab Soil Mechanics Lab CE350CE350 Field DensityField Density 33

How to Get the Volume of the How to Get the Volume of the Hole Hole

Holtz and Kovacs, 1981

Methods(a) Sand cone

(b) Balloon

(c) Oil (or water) method

Calculations•Know Ms and Vh

•Get d field and w (water content)

•Compare d field with d max-lab and calculate relative compaction R.C.

(a)

(b)

(c)

Soil Mechanics Lab Soil Mechanics Lab CE350CE350 Field DensityField Density 44

Sand Cone MethodSand Cone Method

Properties of calibrated sandProperties of calibrated sand

Uniformly graded.Uniformly graded. Spherical in shape.Spherical in shape. Known density.Known density.

Soil Mechanics Lab Soil Mechanics Lab CE350CE350 Field DensityField Density 55

REQUIRED APPARATUSREQUIRED APPARATUS

Density apparatus, consisting of a jar Density apparatus, consisting of a jar with attached cone and base plate with attached cone and base plate

Speedy Moisture Tester.Speedy Moisture Tester. Balance.Balance. Clean, dry Clean, dry

uniform sand ofuniform sand of

known densityknown density

Soil Mechanics Lab Soil Mechanics Lab CE350CE350 Field DensityField Density 66

In the LabIn the LabDetermine the density of calibrated sandDetermine the density of calibrated sand

Type of Sand:Weight of Calibrated Mold:Volume of Calibrated Mold:Weight of mold + sand:

Trial # 1:Trial # 2:Trial # 3:

Average weight of mold + sand:Weight of sand:Density of sand: calibrated sand

Soil Mechanics Lab Soil Mechanics Lab CE350CE350 Field DensityField Density 77

In the LabIn the LabDetermine the weight of sand to fill the Determine the weight of sand to fill the

conecone

Trial # 1 Trial # 2 Trial # 3

Wt. of filling jug after used

Wt. of filling jug before used

Wt. of sand used

Average weight of sand used:

Soil Mechanics Lab Soil Mechanics Lab CE350CE350 Field DensityField Density 88

Weight of jug + cone before used:Weight of jug + cone after used:

Weight of sand used (hole + cone) = Weight of sand in the hole: Wsand =

Volume of the hole: Vh = Wsand /calibrated sand

In the FieldIn the Field

Weight of wet soil + can:Weight of can:Weight of wet soil = Wwet

Red of speedy moisture content: RWater content from speedy moisture apparatus: 1.25*R

Density of Soil:Wet density: wet= Wwet/Vh

Dry density: dry= wet /(1+wc)

Soil Mechanics Lab Soil Mechanics Lab CE350CE350 Field DensityField Density 99

Relative CompactionRelative Compaction

Dry ,max

min=0.95Dry ,max

wopt

Wopt-2% Wopt+2%

LabmaxminF

max d

F d

)(95.0)(

%95 R

d

1

2

34

Soil Mechanics Lab Soil Mechanics Lab CE350CE350 Field DensityField Density 1010

How To Adjust the compaction to How To Adjust the compaction to be acceptedbe accepted

If our point lays in area 1 the Compaction If our point lays in area 1 the Compaction is acceptedis accepted

If our point lays in area 2 we must If our point lays in area 2 we must increase the water content and increase the water content and compaction effort to meet specificationcompaction effort to meet specification

If our point lays in area 3 we must If our point lays in area 3 we must increase the compaction effort increase the compaction effort

If our point lays in area 4 we must If our point lays in area 4 we must Decrease the water content and Increase Decrease the water content and Increase compaction effort compaction effort