Concrete tests are performed to determine whether concrete strength for the use of a structure is adequate, whether the concrete is sustainable during its life cycle, whether there are deteriorations in the concrete itself, etc. Concrete tests should be used appropriately, depending on what qualities and properties you want to determine and the project requirements and usage.
The tests are categorized into two categories; fresh concrete tests and hardened concrete tests. We will first explore the different types of hardened concrete tests.
ASTM C39 Compressive Strength Test
|
Type |
Description |
Method |
Regulatory Documentation |
Result |
|
Compressive strength test |
This test is used to measure the maximum resistance to crushing. The strength of the concrete depends on the cement quality, w/c ratio, concrete aggregate, specimen size, compaction load, and quality of aggregates. |
1. Prepare specimen by mixing cement, water and aggregate
2. Pour concrete into mold and compact using tamping rod to remove air voids
3. Store and mark specimens
4. Remove specimen from molds after 24 hours
5. Prepare specimen for testing after 7 days curing or 28 days curing
6. Apply load until specimen fails and record failure load |
ASTM C39 BS EN 12390-3 BS 1881 - 116 |
Compressive strength = Max applied load / Cross sectional area |
|
Split tension test |
This test is used to determine the tensile strength of concrete, which is the strength to resist cracking under changes in moisture and thermal conditions. Concrete is inherently weak in tension and tends to crack under tension. |
1. Prepare specimen
2. Remove specimens from moulds and submerge them in water
3. Prepare wet specimen for testing after 7 days curing or 28 days curing
4. Apply load at a constant rate from compression test machine until specimen cracks. The load should be applied along the vertical diameter. |
ASTM C496 BS EN 12390-6 BS 1881: Part 117: 1983 |
Tensile strength = 2P/piDL
where P = max applied load D = diameter of specimen L = length of specimen |
|
Flexural strength test |
The test measures the flexural strength of concrete. You can use center point loading or the two point loading setup for the test. |
1. Prepare the concrete beam 2. Position the beam on the apparatus according to your setup 3. Apply the specified load at center of span if the tests is center point loading or L/3 if the test is two point loading. The load should also be perpendicular to the loaded surface of beam. Make sure the applied load does not induce eccentricity. Apply load at the specific rate and increase increment. 4. Determine the beam dimensions after fracture of specimen |
ASTM C-78 Third Point Loading ASTM C 293 Center Point Loading BS 1881 - Part 118: 1983 |
Modulus of rupture value (rectangular concrete sample in center point loading setup) R = 3PI/2bd^2
Where P = max applied load L = span B and d = width and depth of specimen
R = PL/bd^2 (rectangular concrete sample in three point setup)
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