Determination of Compressive Strength
of Cylindrical Concrete Specimens
(ASTM Designation: C 39)
Hussam Khalid Al Mubarak
Abdullah Nasser Al Motairi
Omar Al Shalhoub
Abdullah Al Zeer
Supervisor: Dr Amjed Khabaz
Civil and Environmental Engineering Department
College of Engineering, Engineering Day
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1 April 2013
Objectives
The purpose is to determine the
compressive strength of cylindrical
specimens, either molded or drilled
cores. The method is limited to concrete
having a density of at least 800 kg/m3
(50 lb/ft3).
• The 28-day compressive strength (
)
of molded cylinders is normally used in
design.
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Significance to KSA
Compressive strength of concrete is a primary
physical property and frequently used in
design calculations for the Kingdom concrete
projects as bridges, buildings, and other
structures. Most general-use concrete has a
compressive strength between 20 and 40
MPa (3000 and 6000 psi). Compressive
strengths of 70 to 140 MPa (10,000 to
20,000 psi) have been used in special bridge
and high-rise building applications.
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Description
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Equipment and Materials
• Reusable steel or wax-coated cardboard disposable
cylindrical molds, 15 cm in diameter by 30 cm in height
or 10 cm in diameter by 20 cm in height.
• Moist storage facility for curing the fresh concrete.
• Straight steel tamping rod that is 16 mm in diameter
and about 60 cm in length with one end rounded in a
hemispherical tip
• Rubber mallet weighing about 0.6 kg (1.3 lb)
• A set of special steel caps of appropriate diameter with
a neoprene pad contact with the concrete for capping
the specimen.
• Testing machine capable of applying load continuously
at the rate of 0.14 to 0.34 MPa/s
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Test Procedure
1) Preparation of cylindrical specimens
a. Prepare and cure the specimens in accordance with ASTM
Designation: C 192.
b. Perform air content, slump, and penetration tests on the fresh
concrete prior to casting the specimens in accordance with
ASTM Designations: C 143, C 231, and C 360.
c. Fill the cylinders with three lifts of freshly mixed concrete,
tamping each lift 25 times with the tamping rod. Also tap each
lift lightly with a mallet 10 to 15times.
d. Strike off the excess concrete with the tamping rod and finish to
a smooth surface with a steel trowel.
e. It is recommended that specimens be prepared and tested in
groups of three.
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Test Procedure (Cont.)
2) Curing of the concrete specimens
a. Allow the specimens to set for about 24 hours at
normal room temperature, with the to surface
covered to prevent loss of moisture.
b. Strip the mold from the specimens and place in the
curing facility until ready for testing
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Test Procedure (Cont.)
3) Compression Testing Procedure
a. Remove the specimen from the curing facility just prior to testing.
Specimens shall be tested while still in a moist condition.
b. Measure the diameter of the specimen, determined at right
angles to each other about mid-height of the specimen.
Average the two values to the nearest 0.25 mm (0.01 in.).
c. Center the capped specimens in the testing machine and load at
the prescribed rate of 0.14 to 0.34 MPa/s (20 to 50 psi/s).
d. Load to failure.
e. Record the ultimate load, the angle of fracture, and any other
pertinent aspects of failure such as voids.
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Results
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Results
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Thanks for your attentions
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