Shore Hardness Scale

Summary

Shore Hardness Scale - The Shore Hardness Scale represents the amount of pressure an object or material can endure and the hardness can be defined as the materials resistance to permanent indentation.

Technical Information

There are different scales to demonstrate and measure Shore Hardness with Shore A and Shore D being the most common. The A scale used for softer and the D scale used for harder materials.
When considering concrete industrial floor slabs, it is important to understand the Shore Hardness of the joint sealant used to seal the joints, as requirements can differ for those on a new floor slab and those to repair or reseal an older floor slab.

In a newly laid concrete floor slab it is better to use a softer joint sealant which has greater elasticity, (Movement Accommodation Factor (MAF)), to cope with the natural drying shrinkage of the concrete. Typically a joint sealant with a Shore A Hardness 45. Whereas an older floor slab that is no longer subject to movement from drying shrinkage can afford to have a harder, semi-rigid joint sealant with reduced elasticity (MAF), applied. Typically a joint sealant with a Shore A Hardness of 80 – 85.

An example of good practice when selecting a suitable joint sealant, is to use a semi-rigid joint sealant with a Shore A Hardness of 85 in an older floor slab within a busy warehouse operation. The harder joint sealant will provide better support and is less susceptible to indentation from the hard wheeled materials handling equipment that operate on the floor.

Materials with a Shore D Hardness, such as an epoxy repair mortar, are suited for the repair of damage to the surface of a concrete floor slab, or the repairing of an arris edge.