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Proper sampling methods are required to obtain representative test results on fresh concrete. To achieve a truly random unbiased sample, follow ASTM D 3665, “Standard Practice for Random Sampling of Construction.”. Avoid taking samples from the first and last portions of a batch to obtain a representative sample.
- Acceptance Criteria
- Rules of The Game
- Keeping The Team Informed
- Tracking Test Results
The obvious answer is that those results should be compared to the specified acceptance criteria, but this turns out to be more complicated than it might seem. The keyword here is “specified” meaning as written in the original contract documents, or as added to or modified by a formally accepted change. The acceptance criteria in question may be li...
Once the rules of the game (the acceptance criteria) are clear, further reading and connecting the dots to referenced documents will reveal the details of precisely how the concrete is to be sampled, which tests are to be performed, and how those tests are to be performed (much of this was discussed in the first two articles). Keep in mind, though,...
Although the test results of fresh concrete are known immediately, at least by the test technician, results for compressive, flexural strength or hardened air-void parameters, for example, are not normally available until formal test reports come out. In its mandate to keep the whole team informed, ACI 301-10 requires that “test and inspection resu...
Let’s say the work is progressing and test reports are being provided routinely. What do the contractor and concrete producer do with them? Step 1, normally, is to give the report a quick glance to look for a red stamp that signals an unsatisfactory result. Seeing none, step 2 often entails use of a three-hole punch followed by insertion into a dus...
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In the U.S., a concrete test report provides documen-tation that random samples of fresh concrete have been taken as required in the project specifications and ASTM C172 and that a prescribed series of tests has been conducted in accor-dance with ASTM C31 and C39. Some of the key things that need to be reviewed in a report include:
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Gilson Insights blog: We discuss why it's essential to have consistent concrete cylinder samples for concrete testing and learn reliable testing processes to make it happen.
- Rebound Hammer or Schmidt Hammer (ASTM C805) Method: A spring release mechanism is used to activate a hammer which impacts a plunger to drive into the surface of the concrete.
- Penetration Resistance Test (ASTM C803) Method: To complete a penetration resistance test, a device drives a small pin or probe into the surface of the concrete.
- Ultrasonic Pulse Velocity (ASTM C597) Method: This technique determines the velocity of a pulse of vibrational energy through a slab. The ease at which this energy makes its’ way through the slab provides measurements regarding the concrete’s elasticity, resistance to deformation or stress, and density.
- Pullout Test (ASTM C900) Method: The main principal behind this test is to pull the concrete using a metal rod that is cast-in-place or post-installed in the concrete.
testing agency should report its test results as specified in the contract between the Owner and the general contractor, and as agreed to by the parties at the preconstruction meeting.
Sounding test of concrete is accomplished using a variety of tools. Sounding of small areas and vertical or overhead structural elements is best achieved by using a hammer or steel rod. A steel chain can also be dragged over the surface under evaluation.
