It is used to determine the workability of fresh concrete, provided the maximum size of the aggregate does not exceed than 38 mm. The test is useful for concrete mixes of very low workability, where true slump values are not reliable.
The lateral extensometer is fixed to the help of tightening screws. A Dial Gauge of 12mm or 5mm has been fitted to indicate the lateral extension. The extension is magnified 2.5 times and the dial gauge readings are to be divided by 2.5 to get the exact readings.