BRE Internal Fracture Test Kit (IFT)
The BRE Internal Fracture test kit is designed to test the compressive strength of in-situ concrete.
It does this by applying a torque (twisting) force to a bolt installed into concrete. These torque readings can then be applied to a conversion table to calculate a mean 150 mm concrete cube compressive strength. This is not a ‘true’ Non destructive test however.
Select a test area and wipe the concrete surface clean. Mark the parabolts to be used. Masking tape can be used for this. Place a piece of tape 28-30 mm above the bottom of the bolt. As a check when the hole in the concrete is drilled the parabolt should protrude 55-57 mm from the surface.
Make sure the thread of the parabolt is clean and undamaged, the nut must run freely and create no friction. Use the supplied grease if required.
Assemble the reaction stool and ensure approximately 7 mm of the parabolt protrudes. If it is more than this the bolt is at risk of shearing. Pack the stool out if required.
Prior to drilling use a cover meter to test the area for re bar which could conflict with the tests.
BRE Internal Fracture Test Method
Drill a 6 mm hole in the concrete between 30-50 mm deep, perpendicular to the surface. Clean and remove any dust from the hole and surrounding area. Use the supplied hole reamer and ensure it passes freely in the hole. Failure to do this can lead to high torque readings and inaccurate test results.
Lightly tap the parabolt into the hole until the depth marker (tape) reaches the surface.
Place the reaction stool ring over the parabolt ensuring the exposed bolt does not touch the sides of the plate. Then insert the bearing assembly.
Place a washer onto the parabolt followed by the nut and tighten by hand. Ensure the bearing assembly sits correctly on the reaction stool ring.
Use the torque wrench with 10 mm socket attached and tighten the nut. Count the revolutions until 1 Nm is reached. Then write down the first half turn result and every other thereafter. Complete the half turns slowly and smoothly until the torque gauge starts to drop from its peak during revolutions.
Repeat the test at least six times.
Please don’t hesitate to call us with any queries regarding the BRE internal fracture test kit.