Why We Test Concrete
When dealing with concrete, until the structure has been in service for awhile and experienced a few seasons of freezing or thawing, or the concrete has been loaded to a significant fraction of its design load, the actual long-term performance of the concrete is unknown, therefore, we need test scores such as air content, unit weight, and compressive strength to give us confidence.
How to Prepare for the Test
First start by planning a convenient work zone for the test technician. Things run smoother when it’s easier for the technician to properly sample concrete, perform air and slump tests, make cylinders, and store them in a safe, temperature-controlled environment.
Un-even or un-level surfaces are miserable for slump and air tests, and bad conditions usually increase the apparent slump. The same bad ground makes it harder to consolidate a cylinder.
Of course the actual conduct of the tests is in the hands of the testing technician, which is why most of our standard specifications require certification. Top-grade testing companies do a great job of making sure their people are well trained and certified, but it does not hurt the contractor to reinforce this need and even to verify certification.