Explain Kelly Ball to measure the workability of concrete. Mention the limitation of the test.
KELLY BALL TEST:-
This is a simple field test consisting of the measurement of the indentation made by 15 cm dia. metal hemisphere weighing 13.6 kg when freely placed on fresh concrete. The test has been devised by Kelly and hence known as Kelly Ball Test. The advantage of this test is that it can be performed on the concrete placed in site and it is claimed that this test can be performed faster with a greater precision than slump test. The minimum depth of concrete must be at least 20 cm and the minimum distance from the centre of the ball to nearest edge of the concrete 23 cm.
What is an air entraining agents? Give some examples. What is efflorescence in concrete structure?
Give the physical characteristics of 53 grade OPC.
Differentiate between creep and shrinkage of concrete.
