Mechanical testing for rock strength
Mechanical tests are tests conducted to determine how materials behave under different forces. Consider compressive strength, flexural strength or impact resistance. These tests help predict how a material will behave in real-world conditions so that construction projects are safe and durable.
For example, a brick wall could be prevented from collapsing because the mortar did not prove strong enough. Or that a historic natural stone facade will crack due to freezing weather.
Mechanical testing prevents such problems by detecting weak spots in time.
1. Compressive strength test
The compressive strength test is one of the most common tests. This involves looking at how much pressure a material can withstand before it breaks. This is especially important for natural stone and brick, which are often used in load-bearing walls.
How does it work?
A sample of the material is placed between two plates.
The plates compress the sample harder and harder.
The point at which the material fails is the maximum compressive strength.
Example:
Granite has a high compressive strength, which makes it suitable for foundations. Limestone is less strong, but still usable in less heavily loaded structures.
2. Bending strength test
The flexural strength test determines how well a material can withstand bending. This is important for stones used in window sills or other projecting elements.
How does it work?
The material is supported at two ends.
Pressure is applied in the middle.
The material first bends and then breaks.
Example:
A brick with high flexural strength is less likely to crack when pressure is applied to the top.
3. Tensile strength test
Although bricks and natural stone are rarely loaded to strain, the tensile strength test is important for mortar. Mortar must hold bricks firmly together and withstand stress.
How does it work?
The material is clamped at both ends.
It then pulls on both sides until the material tears.
Example:
Strong mortar with good tensile strength prevents cracks in walls and ensures stable construction.
4. Wear and abrasion resistance
For facing bricks and natural stone floors, wear resistance is crucial. This test measures how well a material resists friction and wear from foot traffic or weathering, for example.
How does it work?
An abrasive substance is rubbed against the material.
After a set time, a check is made to see how much material has disappeared.
Example:
Granite scores high on wear resistance and is often used in public buildings and shopping centers.