Overview
No single test tells the whole story. Rebound hammer and ultrasonic readings survey large areas quickly. Rebar scanning shows what is hidden in the concrete. A small number of cores calibrate the readings and give direct strength values. The value lies in planning the tests well and interpreting them correctly.
Drawings show what a building should be. Testing shows what it is. Non-destructive tests (NDT) assess concrete and reinforcement without damaging the structure. Destructive tests remove small samples, such as concrete cores and pieces of reinforcing bar, so that strength can be measured directly. Used together, they provide the evidence needed for an engineering assessment, a retrofit design, a quality dispute, or a decision to add floors.
When you need it
- As part of a Detailed Engineering Assessment.
- Concrete cube results are low or doubtful, and the cast structure needs to be checked.
- Before adding floors to an existing building.
- After a fire, flood, or impact damages part of the structure.
- Before buying a building whose construction quality is unknown.
What's included
- 01
Rebound hammer test
Surface hardness readings that show how uniform the concrete is and give an indication of its strength.
- 02
Ultrasonic pulse velocity
Pulse readings through concrete members that reveal internal voids, cracks, and variations in quality.
- 03
Rebar scanning
Bar positions, spacing, and concrete cover located without breaking the concrete.
- 04
Concrete core testing
Cores cut from selected members and tested for compressive strength.
- 05
Reinforcement testing
Bar samples tested for yield strength, tensile strength, and elongation.
- 06
Concrete cube testing
Compressive strength of cubes sampled during new construction.
How it works
- 01
Test planning
Test methods and locations are chosen to answer the specific question about the building.
- 02
Site testing
Non-destructive tests are carried out, and cores or bar samples are taken where needed.
- 03
Laboratory testing
Cores, cubes, and bar samples are tested in a laboratory.
- 04
Interpretation and report
The results are combined, interpreted, and reported with clear conclusions.
What you receive
- Test plan
- Which members will be tested, by which method, and why.
- Test results report
- Readings and laboratory results with test locations marked on drawings.
- Engineering interpretation
- What the results mean for the strength of the structure and the original design assumptions.
- Recommendations
- Next steps, from no action to further investigation or strengthening.
Codes & inputs
- ASTM C805 and ASTM C597Standard test methods for the rebound number and the ultrasonic pulse velocity of concrete.
- ASTM C42Standard test method for obtaining and testing drilled cores of concrete.
- BDS ISO 6935-2 and ASTM A615Specifications for deformed reinforcing steel bars used to judge the bar test results.
Core cutting removes a small amount of concrete. Core locations are chosen away from critical reinforcement, and the holes are repaired with suitable non-shrink materials.
Questions about material testing
Will testing damage my building?
Non-destructive tests, such as the rebound hammer, ultrasonic pulse velocity, and rebar scanning, leave no damage. Core tests remove small cylinders of concrete from carefully chosen locations away from critical reinforcement, and the holes are repaired with non-shrink material. The number of cores is kept to the minimum needed for reliable results.
What is the difference between non-destructive and destructive testing?
Non-destructive tests measure properties indirectly, such as surface hardness, pulse speed, and bar positions, without harming the structure, so they can cover many members quickly. Destructive tests, such as core and bar tests, measure strength directly from small samples. A good test plan uses non-destructive tests for coverage and a few destructive tests to calibrate them.
