During compression testing, what type of machine is typically used?

In the context of compression testing, the appropriate equipment used is a compression testing machine. This type of machine is specifically designed to apply a controlled compressive force on concrete samples to determine the material's strength under compression stress. This process involves placing a sample, usually a cube or cylinder, in the machine, which then gradually applies pressure until the sample fails. The machine records the maximum load the specimen can withstand before failure, which is critical for assessing the concrete's load-bearing capacity and overall strength characteristics.

The other types of machines listed serve different purposes and are not suitable for compression testing. A bending test machine is designed to apply loads in a way that causes bending, rather than compressive forces. A shear test machine focuses on measuring the shear strength of materials, which involves forces that act parallel to the cross-section of the sample. An impact testing machine evaluates how materials behave under sudden forces or impacts, which is not relevant to the steady application of compression forces. Therefore, a compression testing machine is the correct tool for this assessment, making it the right choice in this context.