CALIFORNIA BEARING RATIO APPARUTUS (HAND OPERATED):

AS PER IS: 2720 (Part - XVI)

Introduction:

CALIFORNIA BEARING RATIO TEST (CBR)

• The C.B.R. Method is used for finding the relative bearing ratio and expansion characteristics of soil of base, sub-base and sub-grade for the design of roads, pavements and runways.
• Test can be made on all types of soils including sand, gravel, crushed stone etc. (Passing through 20 mm IS Sieve) C.B.R. test is used extensively for selection of materials and control of sub-grades.
• The procedure of test is very simple. A 50 mm dia penetration piston is forced in the test soil and loads required for the penetration to penetrate different depths are recorded by means of a proving ring fixed to the penetration piston assembly and a dial gauge.
• Both Laboratory C.B.R. and field C.B.R. apparatus are available.

General Description and Specifications: The equipment consists one each of the following:

• Load frame: Hand operated, Capacity 5000 kg (50 KN) with high and low rates of travel of the lead screw.
• Mould: made from Gun metal / Brass, 150 mm internal dia x 175 mm high, with perforated base plate and extension collar 50 mm high , tie rods and wing nut.
• Penetration piston: face dia 50 mm, 100 mm long with adjustable bracket for penetration dial gauge.
• Circular metal space disc: 148 mm dia x 47.7 mm high with detachable handle.
• Annular metal weight: 2.5 kg, 147 mm dia with 53 mm dia central hole.
• Slotted metal weight: 2.5 kg, 147 mm dia with 53 dia slot.
• Perforated plate: made of Gun-metal / Brass, 148 mm dia with adjustable stem and lock nut.
• Metal tripod: for dial gauge.
• Cutting collar: for obtaining sample from field.
• Rammer: 2.6 kg weight with drop of 310 mm, controlled drop through guide.
• Rammer: 4.89 kg with drop of 450 mm, controlled drop through guide.
• Proving ring:  high sensitivity, capacity 1000 kg with calibration chart and carrying case. Dial gauge graduated 0.0002 mm, range 5 mm.
• Strain dial gauge: least count 0.01 mm x 25 mm travel.