Category: Structure & materials
Prepared by Eng. Ahmed Fathy, Projects Manager ·
Definition
The core test drills cylinders, commonly 100 mm in diameter, from a hardened concrete member and crushes them to measure its actual strength. It is used when cube results are low or the quality of an existing member is in doubt.
Why it matters on a project
It settles disputes about a cast member without demolishing it. Under the ACI code concrete is usually accepted if three cores average at least 85% of the specified strength and none is below 75%.
Measurement and pricing
Per core including drilling, testing and making good the hole.
Worked example
Specified 30 MPa and three cores of 27, 25 and 28: average 26.7 = 89% of specified, lowest 25 = 83%, so accepted under the 85% and 75% criteria.
Common mistake
Drilling where reinforcement is dense without scanning first, cutting bars and spoiling the core.
Frequently asked questions
Does coring weaken the member?
Cores are taken at low-stress points with the designer's approval, and holes are filled with non-shrink repair mortar.
What if the cores fail?
The designer decides between a load test, strengthening or removing the member.
Related terms
- Concrete cube testCubes taken during the pour and crushed to measure concrete strength.
- Concrete grade (compressive strength)The characteristic compressive strength of concrete at 28 days, e.g. C30 or 300 kg/cm².
- Third-party inspectionIndependent testing by an accredited body separate from contractor and owner.
- NCR (non-conformance report)A report recording work or material not meeting the specification, with root cause and corrective action.
Read next
Does your project need structural design and reinforcement drawings? Send the drawings or a short description and we reply within one working day.
Service detailsRequest a quote