Per §5.4.5, in the Kelly Ball test the minimum depth of concrete neede…

Question

Per §5.4.5, in the Kelly Ball test the minimum depth of concrete needed for a valid result is:

Accepted Answer

C. {'text': '20 cm', 'label': 'C'}

1. §5.4.5: 'The minimum depth of concrete must be a minimum of 20 cms and minimum distance from the centre of the ball to nearest edge of concrete has to be minimum 23 cms.'
2. The procedure (level surface, place tester, lower the ball gradually, read to nearest 6 mm) takes only ~15 seconds per measurement.
_Source: IGNOU ET-522 Block-2 Unit-5 Workability & Fresh Concrete-I, §5.4.5, p. 13_

Answer

{'text': '5 cm', 'label': 'A'}

Answer

{'text': '10 cm', 'label': 'B'}

Answer

{'text': '50 cm', 'label': 'D'}