ABSTRACT
Concrete when not reinforced has considerable strength in com pression but very little strength in tension; the ratios varying between about 10:1 and 15:1. Having a low tensile strength, it follows that concrete is weak in bending, shear and torsion. The tensile strength besides being low is also unreliable: it may be entirely destroyed by shock or sudden jar, or as a result of shrinkage arising from setting or drying, or due to thermal contraction. Hence the use of unreinforced concrete is normally limited to applications where great compressive strength and weight are the principal requirements, and where tension and bending stresses are either totally absent or, if they occur at all, are extremely small. Examples of the use of unreinforced concrete include thick spread foundations, dock walls, dams, gravity retaining walls, and certain arch types.
