Stone

The material. Stone is the most durable of all building material. The Pyramids (before 3000 BC), the Parthenon (5th century BC), and the cathe­drals of Europe (1000-1600 AD) testify to the resistance of stone to attack of every sort. It remained the principal material of construction for impor­tant buildings until the early 20th century; the railroads of the world, for example, could not have been built without stone for the viaducts and sup­port structures. As the cost of stone increased and brick became cheaper, stone was increasingly used for the outer structure only; today it is largely used as a veneer on a concrete or breezeblock inner structure. Carefully selected samples of fully dense, defect-free stone can have very large com­pressive strengths—up to 1000MPa. But stone in bulk, as used in buildings, always contains defects. Then the average strength is much lower. The data given here is typical of bulk sandstone with a porosity of 5-30%. Bulk lime­stones are a little less strong, granites somewhat stronger.

Composition

There are many different compositions. The commonest are made up of calcium carbonate, silicates, and aluminates.

Stone, like wood, is one of man’s oldest and most durable building materials.

Electrical properties

Typical uses. Building and cladding, architecture, sculpture, optical benches for supports for high-performance or vibration-sensitive equipment such as microscopes.