Concrete checking test at the site to achieve the desired quality, strength, and durability also useful to reduce the duration for that particular slab, column casting at the site.

1. Training for Staff.
CONCRETE CHECKING
TEST
Prepared By - Qualityconstructionwork.com

3. Equipment's to be used during checking of Slump:
Tamping Rod
Slump Test Cone
Measurement Tape or Ruler
Hand Gloves

4. Slump Test Cone:-
Size:- 100mm Smaller opening at Top diameter and 200mm Base
diameter 300mm height of Slump Cone.
It consist of lifting handles and foot rests.
Tamping Rod:-
Size:- 600mm in length
16mm in diameter

7. Types Of Slump:

8. Results:- 120 +/- 30 Slump

9. FLOW TABLE TEST
The flow test is used for high workability concrete (with a slump of more that 175
mm).
The 700 mm square flow table is hinged to a rigid base, proved with a stop that allows
the far end to be raised by 40 mm.
A cone, similar to that used for slump testing but truncated, is filled with concrete in
two layers.
Each layer is tamped 10 times with a special wooden bar and the concrete of the
upper layer finished off level with the top of the cone.

10. • After waiting 30 s from striking off the concrete, the mould shall be raised vertically
by holding the handles, over a period of 1 s to 3 s. With the flow table being
stabilized by standing on the toe board at the front of the table, the table top shall
be raised slowly till it reaches the upper stop in such a manner that the table top
does not impact hard against the upper stop and then allowed to fall freely to the
lower stop.
• This operation shall be repeated to give a total of 15 times, each cycle taking not
less than 1 s nor more than 3 s. The maximum dimension of the concrete spread in
the two directions, d1 and d2, parallel to the table edges shall be measured to the
nearest 10 mm with the aid of measuring jig and recorded.

11. BLEEDING:
Due to bleeding,concrete loses its homogeneity.
In the process of bleeding (i.e. while water is in the process of coming towards top)
sometimes gets accumulated below the aggregate. This accumulation of water creates
a water voids and reduces bond between the aggregate and cement past. So the
strength of concrete reduces
SEGREGATION:
As well as getting an accurate measurement of the workability of the concrete, the
flow test gives an indication of the cohesion. A mix that is prone to segregation will
produce a non-circular pool of concrete. Cement paste may be seen separating from
the aggregate.
If the mix is prone to bleeding, a ring of clear water may form after a few minutes.

12. Normal Segregation
Photograph of Segregation
Bleeding

13. • Loss of workability( Effect of Extension of Retension Time
)
• The concrete should always be laid in position without loss of time to avoid
setting and stiffening of concrete to reduce its workability. When the transit
time is high, it will have effect on workability of concrete.
• This happens due to hydration reaction taking place when cement
mixes with water, evaporation of mixed water in concrete and due to
absorption of water by aggregates.
• While the workability of concrete depends on many factors such as the
constituent material, mixed proportion, ambient temperature, humidity and
method of transport etc., the reduction in workability may lead to difficulty in
placement of concrete. Thus, while planning for use of Ready Mixed
Concrete, the aspect of loss of workability in the likely transit time involved
should be taken into account.
• By measuring slump or compacting factor of concrete immediately after
mixing at RMC plant and after transit time, loss of workability may be
estimated.

14. In order to reduce rate of loss of workability generally water reducing agent / super
plasticizer is used

15. • Addition of Water in Concrete:
• Addition of water / admixture in concrete at site to restore the workability, provided
requirement for uniformity.
• Uniformity requirement specify variation limits for properties like slump,
compressive strength & density etc.
• At site, there is no way to judge whether specified uniformity requirement are met or
not.
• Moreover, addition of water affects the strength and durability characteristic of
concrete. Thus, it is advised that re-tempering i.e. addition of water after mixing,
should not be permitted at all either during transit or at the site of construction.

16. THANK
YOU..