In a standard penetration test, what is the weight of the hammer and the dropping height used as per IS 2131–1981?
Standard Penetration Test (SPT)
The standard penetration test (SPT) is the most extensively used in situ test in India and many other countries. This test is carried in a borehole using a split spoon sampler. As per IS: 2131-1981, the steps involved in carrying out this test are as follows:
(i) The borehole is advanced to the depth at which the SPT has to be performed. The bottom of the borehole is cleaned.
(ii) The split spoon, attached to standard drill rods of the required length, is lowered into the borehole and rested at the bottom.
(iii) The split-spoon sampler is seated 150 mm by blows of a drop hammer of 65 kg falling vertically and freely from a height of 750 mm. Thereafter, the split spoon sampler shall be further driven 300 mm in two steps each of 150 m. The number of blows required to affect each 150 mm of penetration shall be recorded. The first 150 mm of the drive may be considered to be a seating drive. The total blows required for the second and third 150 mm of penetration is termed the penetration resistance N.