Concrete Cube and Cylinder Testing: Machine Configuration Guide
A cube and a cylinder need more than the same rated force. Use their geometry, end condition and governing test method to define a compression-machine configuration.
Define the specimens before choosing the frame
A concrete cube compression testing machine must accommodate the cube's bearing area and height. A concrete cylinder compression testing machine must accommodate the cylinder diameter, height and any end-preparation fixtures. Specify dimensions explicitly instead of asking only for a machine for concrete.
At 80 MPa, a 150 mm cube requires an estimated 1800 kN, while a 150 mm diameter cylinder requires about 1414 kN. This compares machine loads only; it is not a conversion between cube and cylinder test results.
Configuration information to provide
| Check | Cube testing | Cylinder testing |
|---|---|---|
| Specimen geometry | Side lengths and loading orientation | Diameter, height and end condition |
| Loaded area | Side × side for a square face | π × diameter² ÷ 4 |
| Test-space requirement | Cube plus bearing blocks and spacers | Cylinder plus caps or other end fixtures, bearing blocks and spacers |
| Method context | Project-specified method, such as EN 12390-3 | Project-specified method, such as ASTM C39 or EN 12390-3 |
Match platens, bearing blocks and spacers
Use a drawing of the complete load path to check the quoted configuration. Review the bearing-face size, seating arrangement, specimen centering, vertical clearance and working piston travel. Ask which spacers are included for each specimen size and how the operator changes between them.
A platen diameter alone does not establish compliance with a test method. The bearing assembly and its verified condition must be suitable for the specimen and governing procedure. Keep access for loading and removal in the layout review, including any guard or enclosure.
Plan specimen preparation and the test record
Cylinder ends require preparation accepted by the governing procedure. Grinding and capping are separate preparation approaches with method-specific conditions; select the approach before specifying accessories. A cylinder end grinder is preparation equipment, while the compression machine applies the strength-test load.
Before purchase, define the record you need: specimen ID, geometry, measured dimensions, test age, maximum load, calculated strength and other method-required observations. Ask for a sample report from the proposed controller and check whether the laboratory can retain the required data.
- Send the supplier a specimen schedule with dimensions and expected strengths.
- Identify the governing test method and edition.
- Agree the bearing assembly, spacers and end-preparation equipment.
- Check the installation drawing, calibrated load range and sample test record.
Frequently Asked Questions
Can one compression machine test both cubes and cylinders?
Yes, if the frame, calibrated force range and fixture configurations cover both specimen schedules. Confirm the bearing assemblies, spacers and preparation method for each format.
Does ASTM C39 cover concrete cube testing?
ASTM C39/C39M covers cylindrical concrete specimens. Use the cube test method specified by the project and review its machine and specimen requirements separately.