SOLVE

CALIFORNIA BEARING RATIO TEST ON SOIL

Objective:

To determine California Bearing Ratio value of soil by conducting load penetration test.

Apparatus used:

CBR Setup, CBR Mould, Filter Paper, Rammer, Plunger, Spacer Disc, Surcharge Weight, Slotted Weight.

STEP 1

Take sample, sieve it in 20mm IS sieve using mechanical shaker and then add measured quantity of water to it.

Volume of water taken (Total weight of soil(w) x 18%) = 900ml

STEP 3

Fill one fifth of the mould with the soil sample. Each layer is compacted by giving 56 evenly distributed blows using a hammer of weight 4.89kg.

STEP 5

Specimen is placed in position on the testing machine along with the half weight and plunger. Load at penetration of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.5, 10.0 and 12.5mm are noted.

Penetration (mm)

Proving ring reading

STEP 6

Observation and Calculations.

Diameter of plunger = 50mm

Area of plunger = 19.63cm²

Optimum moisture content = 15%

Load(kg) = ^{^{Proving Ring Reading * 5}⁄₂₂₅*1000}⁄_9.81

Axial Load(kg/cm²) = ^Load(kg)⁄_{Area of plunger}

**Enter key to be pressed to save values in table**

Penetration (mm)

Proving ring reading

Load in (kg)

Axial load in (kg/cm²)

STEP 8

Observation and Results.

Unit standard load for 2.5mm = 70kg/m²

Unit standard load for 5mm = 105kg/m²

California Bearing Ratio CBR_2.5mm = ^{Load corresponding to 2.5mm penetration(P_r)}⁄_{Standard load corresponding to 2.5mm penetration (P_s)} * 100

=⁄₇₀ * 100

California Bearing Ratio CBR_5mm = ^{Load corresponding to 5mm penetration(P_r)}⁄_{Standard load corresponding to 5mm penetration (P_s)} * 100

= ⁄₁₀₅ * 100

Refer Graph

Need Hint?

Soil Type	CBR Range
Sandy Soil	5% - 40%
Fine grained Soil	5% - 15%

CALIFORNIA BEARING RATIO TEST ON SOIL

Objective:

Apparatus used:

Since the soil is within the specified range it is suitable for pavement construction