A Laser Extensometer of the type P-50 was used for measurement of strain at a high strength concrete specimen.
The concrete specimen was marked with two white sticky stripes defining a measuring length of 30 mm.

Stress-Strain Diagram during
Simple Compression Experiment

The specimen was compressed until 0.05 % resulting in a stress of 16 MPa.
At a further experiment the specimen was loaded cyclically. The loading sequence can be seen in the diagram of stress and strain versus time.
The figure on the lower right shows two hysteresis loops - one with a small and another with a large amplitude.