Compressive Strength

A key difference between UKCSA Full Members and other cast stone manufacturers is the high compressive strength of their products, which makes them significantly more robust and durable.

The minimum standard required of UKCSA Full Members represents over 40% increase in compressive strength above that indicated in the British Standard for Cast Stone, BS 1217, and at least 75% above the minimum requirement in the Standard for Manufactured Stone, BS EN 771-5.

UKCSA’s performance test stipulates that: the average crushing strength of 3 cubes tested to BS EN 12390: Part 3 shall not be less than 35 MPa at 28 days old. No individual cube is to have a strength less than 28 MPa.

The UKCSA strength requirement came as a result of a two year Partners in Technology research project into cast stone, undertaken by Dundee University and co-funded by the UK Cast Stone Association and the UK Government.

Testing Cast Stone

This project concluded that in accelerated weathering tests all dry-cast Cast Stone tested weathered in a similar way to natural stone. However, and more importantly to the Association, the overall recommendation of the project was that to ensure performance and durability of Cast Stone, the minimum cube strength requirement should be increased to 35 MPa.

The UK Cast Stone Association welcomed this proposal and since 2000, all cast stone manufacturing Full Members are required to achieve a minimum compressive cube strength of 35 MPa as a condition of their membership, and test results have to be submitted to the Association on a regular basis to prove compliance with this requirement.

Typical compressive strength of building materials, include:

  • Minimum 35 MPa:             Cast Stone – supplied by an UKCSA Full Member.
  • Typically 35 to 50 MPa:     Cast Stone – supplied by an UKCSA Full Member.
  • Minimum 25 MPa:             Cast Stone – to BS 1217, Specification for Cast Stone.
  • Minimum 20 MPa:             Manufactured Stone – to BS EN 771-5 for Manufactured Stone.
  • Typically 12 MPa:                 Limestone – low density
  • Typically 28 MPa:                Limestone – medium density
  • Typically 55 MPa:                Limestone – high density
  • Typically 14 to 60 MPa:     Sandstone
  • Typically 7 to 20 MPa:       Many Clay Bricks (source BDA)
  • Typically under 1 MPa:     The core material strength of EPS foam stone products