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Slump Flow Test on Self Compacting Concrete for Workability

Concrete Slump Test

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Slump Flow Test and T 50 cm Test on Self Compacting Concrete

The slump flow test is used assess the horizontal free flow of self compacting concrete in the absence of obstructions. It was first developed in Japan for use in assessment of underwater concrete.

The test method is based on the test method for determining the slump. T is the diameter of the concrete circle is a measure for the filling ability of the concrete.

Assessment of Slump Flow Test

This is a simple, rapid test procedure, though two people are needed if the T50 time is to be measured. It can be used on site, though the size of the base plate is somewhat unwieldy and level ground is essential.

It is the most commonly used test, and gives a good assessment of filling ability. It gives no indication of the ability of the concrete to pass between reinforcement without booking, but may give some indication of resistance to segregation.

It can be argued that the completely free flow, unrestrained by any foundries, is not representative of what happens in concrete construction, but the test can be profitably be used to assess the consistency of supply of supply of ready-mixed concrete to a site from load to load.

Equipment for Slump Flow Test

The apparatus is show in figure;

Equipment for Slump Flow Test

Equipment for Slump Flow Test
Fig. 1: Accessories for Flow cone Flow table Slump test
Fig. 2 Slump flow test and T 50 cm test

Procedure of Slump Flow Test on Self Compacting Concrete

About 6 liter of concrete is needed to perform the test, sampled normally. Moisten the base plate and inside of slump cone, place base plate on level stable ground and the slump cone centrally on the base plate and hold down firmly.

Fill the cone with the scoop. Do not tamp, simply strike off the concrete level with the top of the cone with the trowel.

Remove any surplus concrete from around the base of the cone. Raise the cone vertically and allow the concrete to flow out freely.

Simultaneously, start the stopwatch and record the time taken for the concrete to reach the 00mm spread circle (This is the T50 time).floatable test, might be appropriate.

The T50 time is secondary indication of flow. A lower time indicates greater flow ability. The Brite EuRam research suggested that a time of 3-7 seconds is acceptable for civil engineering applications, and 2-5 seconds for housing applications.

In case of severe segregation most coarse aggregate will remain in the centre of the pool of concrete and mortar and cement paste at the concrete periphery. In case of minor segregation a border of mortar without coarse aggregate can occur at the edge of the pool of concrete. If none of these phenomena appear it is no assurance that segregation will not occur since this is a time related aspect that can occur after a longer period.

Read More:

Various Tests for Workability of Concrete at Construction Site and Recommended Values

What is Workability of Concrete? Workability vs. Strength of Concrete

Concrete Slump Test – Procedure and Results

Factors Affecting Workability of Concrete

Concrete Workability – Slump & Compacting Factor Values and Uses

Vee-Bee Test to Determine Concrete Workability using Consistometer

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