Objective

For determination of consistency of concrete where the nominal maximum size of aggregate does not exceed 38 mm using flow table apparatus. 

Reference Standard

IS : 1199 – 1959 – Method of sampling and analysis of concrete.

Equipment & Apparatus

• Flow table 

Procedure

1. Before commencing test, the table top and inside of the mould is to be wetted and cleaned of all gritty material and the excess water is to be removed with a  rubber squeezer.
2. The mould is to be firmly held on the centre of the table and filled with concrete in two layers, each approximately one-half the volume of the mould and rodded with 25 strokes with a tamping rod, in a uniform manner over the cross section of the mould.
3. After the top layer has been rodded, the surface of the concrete is to be struck off with a trowel so that the mould is exactly filled.
4. The mould is then removed from the concrete by a steady upward pull.
5. The table is then raised and dropped from a height of 12.5 mm, 15 times in about 15 seconds.
6. The diameter of the spread concrete is the average of six symmetrically distributed caliper measurements read to the nearest 5 mm.

Calculation

The flow of the concrete is the percentage increase in diameter of spread concrete over the base diameter of the moulded concrete, calculated from the following formula.

Report

The flow measured is to be reported in terms of percentage. 

Safety & Precautions

• Use hand gloves, shoes at the time of test.
• Keep the mould & flow table clean, dry & free from sticking concrete.
• Keep the vertical shaft lubricated with light oil.
• Keep the contact faces of the flow table top & supporting frame oiled.
• Keep the hand wheel, the adjustable shaft & universal joint.