The compression testing machine is the central instrument of a concrete laboratory, and choosing the wrong one is costly: either the machine fails to cover the required strength range, or the laboratory overpays for capabilities it does not need. The first criterion is the load range. The working point should fall within 20–80% of the scale: for 100 mm cubes and concrete classes B15–B60 a 1,500 kN machine is usually sufficient, while for 150 mm cubes and high-strength concrete you should consider 2,000–3,000 kN.
The second criterion is the accuracy class of the force measurement system. An accredited laboratory requires Class 1 to GOST R 8.663 across the entire working range, and it is important to ask the supplier about the lower limit of the measuring range: on budget machines, Class 1 accuracy is often confirmed only from 10% of the scale upwards.
The third criterion is frame stiffness and platen quality. A compliant frame distorts the failure mode of the specimen, and platen flatness deviations beyond the GOST 10180 tolerance systematically underestimate the result. Pay attention to the hardness of the platen working surfaces (at least 55 HRC) and the presence of a self-aligning upper platen.
The fourth criterion is automation. Automatic control of the loading rate eliminates operator influence and is essential for a high throughput of specimens. Useful features include automatic detection of the failure point, report export and the option to connect a second load frame — for example, for flexural testing of prisms.
Finally, assess the cost of ownership: availability of spare parts, the cost of annual calibration, and the presence of service support in your region. In-Test engineers will help you select a model for your concrete classes and testing volumes — send us an enquiry describing your tasks.