The use of the in-situ CBR apparatus on large road construction projects has increased considerably in recent years. This apparatus, mounted on a rolled steel joist cantilevered from the back of the truck or fitted to the underside of a mobile frame, can be used to determine the bearing capacity of soils quickly and efficiently. This method of testing in-situ, using piston penetration, is useful for determining the load carrying capacity in the field, when the in-place density and water contents are such that the degree of saturation is 80 % or greater, when the material is coarse grained and cohesion less so that it is not affected by changes in the water content and when the material has been in place.
CBR Test Apparatus It consists of:
- Loading Jack with U-bracket, capacity 50 kN (5,000 kgf). This is specially designed for use with Field CBR test apparatus. It consists of a hand operated, two speed, screw jack fitted with a U-bracket. A hexagonal adapter is provided to fix a proving ring. A thrust bar, which passes through the U-bracket, is screwed on to a proving ring (supplied at extra cost) which protects the proving ring when the loading is eccentric.
- Swivel Head Swivel Head
- Penetration Piston 50 mm dia threaded at the upper end, to connect to the various lengths of extension sleeves, through a connector
- Extension Set consisting of 1 length of 5 cm, 2 lengths of 10 cm, 1 length of 30 cm, 1 length of 50 cm and a length of 100 cm used as spacers between the proving ring and penetration piston. The lengths are machined from steel tubing
- Connector Set has eight connectors for coupling the penetration piston and proving ring assembly, either directly or through extension pieces
- Datum Bar Assembly consisting of two stands and 1 m long Bar
- Adjustable Bracket for mounting the Dial Gauge
- Annular Metal Weight 5kg, 250 mm dia with 53 mm dia central hole
- Slotted Metal Weight 5kg, 215 mm to 250 mm dia with 53 mm dia slot, 2 Nos.
- Slotted Metal Weight 10kg, 215 mm to 250 mm dia with 53 mm dia slot, 2 Nos.
- Dial Gauge 0.01×25 mm
- Proving Ring 50 kN (5,000kgf) capacity