17-01-2014, 02:54 PM
TESTS ON FRESH CONCRETE
AIM
To determine the workability of fresh concrete by slump test as
per IS: 1199 - 1959.
PROCEDURE
i) The internal surface of the mould is thoroughly cleaned and
applied with a light coat of oil.
ii) The mould is placed on a smooth, horizontal, rigid and non-
absorbent surface.
iii) The mould is then filled in four layers with freshly mixed
concrete, each approximately to one-fourth of the height of
the mould.
iv) Each layer is tamped 25 times by the rounded end of the
tamping rod (strokes are distributed evenly over the cross-
section).
v) After the top layer is rodded, the concrete is struck off the
level with a trowel.
vi) The mould is removed from the concrete immediately by
raising it slowly in the vertical direction.
vii) The difference in level between the height of the mould and
that of the highest point of the subsided concrete is
measured.
REPORTING OF RESULTS
The slump measured should be recorded in mm of subsidence of
the specimen during the test. Any slump specimen, which
collapses or shears off laterally gives incorrect result and if this
occurs, the test should be repeated with another sample. If, in
the repeat test also, the specimen shears, the slump should be
measured and the fact that the specimen sheared, should be
recorded.