Aim: To prepare specimens for the test of
Compressive Strength of concrete.
Apparatus: Cube mould fitted tightly on
base plate (size in mm 150x150x150) in required set (One set comprises
of 6 mould.)
Smooth Tamping rod of size 16 mm dia and length of 600 mm with
one rounded edge. Trowels small and large, Collection pan, scoop,
measuring scale etc., Flat working platform of adequate size.
Procedure of Cube Casting:
- Cube mould shall be verified for dimensions and tight fitting
assembly. They shall be lightly oiled and have clean surfaces.
- Cube mould shall be arranged in sets on working platform.
- Sample is collected as per the procedure given earlier.
- Concrete is filled in cubes one by one in three layers. Each
layer is tamped 35 times with tamping rod evenly. Tamping shall
penetrate the layer below. Care to be taken particularly at corners.
Small trowel can be used at the sides to ensure proper surface of
sides and allow entrapped air to escape.
- Cubes shall be filled slightly above top surface of mould.
- The top extra layer shall be struck off by large trowel,
flush to the top.
- Cubes shall not be disturbed till at least 6 hours after the
- Cube concrete surface shall be marked with Cube I.D. , Mix,
location of use, date, source of concrete ( additional) when
- Cubes thus cast, shall be covered with wet gunny bags till
they are replaced in curing tank.
- After setting of cubes can be opened and place those in
- Cubes shall be checked for surface correctness, sharp edges
and incorrect filling.
- Such defective cubes may be rejected there itself. In such
case Corrective /Preventive actions shall be taken.
Procedure for Tank Curing:
- Cubes shall be arranged in the curing tank sequentially as
per ID mark, date wise.
- Cubes shall be sorted out for 7 days, 28 days tests. Cubes
shall be placed in the tank in layer of three cubes with marked top
- Cubes once placed in tank shall not be handled, disturbed
frequently so that edges are not broken.
- Water in tank shall cover cubes by at least 50-75 mm all the
- Water temperature must be maintained in winter.
Details of Cubes thus sampled shall be entered serially in Cube
Register maintained for testing compressive strength
The number of cube samples cast shall also be entered in pour
card with proper traceability to cube register
Format to be used: It shall be recorded in Cube register