There are several means of evaluating the in-place strength of concrete. Depending on your needs, you can choose from different strength test methods like maturity testing, the Windsor probe test, pullout test, and the rebound hammer test. Here are things you should remember when using each:
- Maturity testing is said to the best method to test the real strength of concrete because it allows you to estimate the core strength of concrete by analyzing its maturity curve and compressive strength. Maturity testing saves time as it requires fewer test points to set up as opposed to other methods. This also translates to great cost savings.
- Windsor probe testing involves penetrating the surface of the concrete to be tested with a hardened steel probe, fired through a gun via a powder-filled cartridge. Strength is measured by the depth of penetration. An important thing to remember when using Windsor probing is that penetration resistance and concrete strength may differ between concrete materials as well as mixture proportions.
- Rebound hammering is applicable when assessing the in-place uniformity of concrete as well as to estimate its test. This, however, requires correlation of rebound numbers on the structure and the core strengths of different locations in the tested concrete, making the test cumbersome and time-consuming, not to mention the possible calibration issues you might encounter.
- Pullout testing, on the other hand, is a minimally destructive testing method although the pullout site is usually easy to patch. It involves inserting a round metal head and shaft into fresh concrete. The load on the pullout shaft is then increased to failure to take out a piece of concrete. Its pullout strength can be related to the compressive strength of the concrete. Perhaps the most important thing to remember when performing concrete strength testing is to find the most appropriate method for your particular application.
Papworths Construction Testing Equipment (PCTE) 