It is used for finding out rate of hardening of mortars sieved from concrete mixtures.
The instrument consists of a barrel housing a calibrated spring and a stem graduated from 0-70 kg X 1 kg. six interchangeable penetration needles of areas 645,323,65,32 and 16mm sq. are provided. The penetration resistance is measured by the force exerted to penetrate the mortar by 25mm and is indicated by a sliding ring on the stem, which is graduated . Needle shanks are marked at every 12.5mm. compete in a wooden carrying case.