SCOPE:
To determine compression strength of concrete cube as per IScode.
IS CODE: IS: 516 - 1959
APPARATUS:
Compression testing machine
PROCEDURE:
a) Check the specimens whether it is dry or wet, if it is dry means place the sample in the curing tank for 24 hours.
b) Check the age and grade of test specimen, noted in observation sheet.
c) Measure the dimension of the cubes and enter Area of the cube in observation sheet.
d) To find the weight of specimen by using weighing scale & Noted in observation book.
f) Place the specimen in the center the compression testing machine.
g) Apply the load gradually without shock and continuously at the rate of 140 kg/cm2/minute till the specimen fails.
h) Report all results separately for each unit and as the average for the three units.
CALCULATION:
Compressive strength = {Failure Load / Area} × 1000, (n/mm2)
SPECIFICATIONS:
An approximate formula for expressing the strength of concrete at any age t (in days).
where,
f28 is the strength at 28 days.
a and b are empirical constants.
The age factor given in the Code cor
responds to approximately a= 4.7 and
b=O.833 in the above formula.
For example,
The strength at 7 days for M 15
grade concrete is,
=0.664×15
=9.96 N/mm2
=10.0 N/mm2