IS 2720 (PART XXXI) 1969.
In recent years it has become important to know C.B.R. values in situ. It is useful in determining the load carrying capacity in the field when in place density and water contents are such that the degree of saturation is 80% of greater, when material is cohesionless and coarse grained, such that it is not effective by changes in water contents and when the material has been in place for considerable the loading is effected by means of a mechanical load frames which can be fixed to the under side of a truck.
Mechanical screw loading jack, 10,000 kg. Capacity with u-bracket and swivel head. Penetration piston, 50mm dia. Threaded at the upper end. Extension rods consisting of 2 lengths 5 cm. g lengths 10cm. 1 length 30 cm., 1 length 50 cm. and 1 length 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. Dial gauge support of seamless pipe constructions. It stands 30 cm high and 45 cm. Wide at the base. Provided with a quick release screw type clamp capable of sliding and locking anywhere along 2 meter length of the bridge. Supplied with annular metal weight 5 kg., 250mm dia with 53 mm dia central hole, slotted metal weight 5 kg., 215mm to 250mm dia with 53 dia slot 2 nos.