Brittleness

Materials which are Brittle break suddenly with little or no deformation first - like a stick of chalk or a potato crisp! (ie. they have little or no Plasticity). This can make them very dangerous in engineering situations since components may snap without warning, but they are also strong in Compression.

One solution when using normally Brittle materials such as Concrete is to keep them in Compression even when they are deployed in situations which may expose them to Tensile Forces.

This achieved for Pre-Stressed Concrete Beams for example by casting the concrete around steel rods or wires which have been first stretched such that when the concrete sets they continue to pull the ends of the beam inwards. Similarly, Toughened Glass is heat treated such that the resulting tempering puts the outer surfaces into compression and the inner surfaces into tension.