Testing Fresh ConcreteFor the smaller residential concrete contractor, concrete testing may not be routine practice and even seem like an inconvenience. But the relatively small cost associated with testing pays for itself rather quickly when problems or questions arise on projects.

Assessing the properties of fresh concrete during placement leaves a contractor in a better position to respond to any problems that ensue, such as low strength or cracking. Fresh concrete test data such as slump and air content can help indicate possible causes and guide the troubleshooting investigation. Was excess water added? Was the air content too high or too low?

You should take concrete testing seriously and start off on the right foot by securing the services of a certified testing laboratory (see ASTM C 1077) employing field and lab technicians that are ACI-certified. This will give you the greatest assurance that proper sampling and proper field and laboratory tests are conducted.

How to Investigate Problems with Hardened ConcreteA new concrete driveway you saw being placed a few months ago got your attention again as you drove by today. You see a meeting taking place on that driveway with what appears to be the homeowner, contractor and a couple of guys in suits with pads of paper taking notes. In the background, you notice a worker drilling into the driveway. Putting holes in a brand new driveway? What's going on?

The meeting you witnessed may be due to a homeowner who is dissatisfied with his final product. The source of dissatisfaction could be almost anything. Typical complaints include flaking or scaling of the surface, uncontrolled cracking, discoloration and popouts.

Projects of all sizes can encounter problems. Most are small enough that they can be quickly and economically resolved by contractors wanting to keep customers happy. However, some issues can be significant in terms of cost and time, involving an entire project or even a whole subdivision. Such defects should be examined to find the cause so that the proper repair is administered. This process, although inconvenient, allows the parties involved to discover the cause of the defect and learn how to avoid it in the future.

Here are the general steps involved in examining a defect and some common practices and tests typically used to search for the cause. Remember that each situation is unique, and the specific issue encountered on your project may require different tests to obtain the needed information. Discuss the testing program with an experienced professional to set up a sampling/testing plan appropriate for the actual defect you might encounter.