Apparecchio Kelly Ball

Kelly Ball Apparatus is a ball-penetration test device designed to quickly and repeatably evaluate the workability of fresh concrete in the field or laboratory. The device consists of a weight body carrying a 6 in (152 mm) diameter hemispherical steel ball, a guide frame that maintains vertical alignment of the ball, and a graduated measuring stem. The penetration depth of the ball into the fresh concrete surface is read directly from the pointer on the stem, enabling consistency comparison between mixes. The weight-ball assembly has a mass of 30 lb (≈14 kg). It is manufactured from a corrosion-resistant material. The measuring stem is dual-graduated in inch subdivisions and metric scale, allowing accurate readings in different reporting formats. The device architecture is configured to meet the dimensional and reading requirements of ASTM C360. It is used for on-site inspection of freshly placed elements, monitoring reference samples taken from fresh concrete, and in production-stage quality-assurance processes.