Concrete has relatively high compressive strength but significantly lower tensile strength, as result concrete to would almost always fail from tensile stress even when loaded in compression. The practical implication of this is that concrete elements subjected to tensile stresses must be reinforced with materials that are strong in tension (often steel) the ultimate strength of concrete is influenced by the water-cementations ratio (w/c). the design constituents, and the mixing placement and curing methods employed, all things being equal. Concrete with a lower water-cement ratio makes a stronger concrete than with a higher ratio.

Determining the mix design of concrete should be such as to satisfy the following conditions :

The performance and fluidity of the concrete can be sufficient to allow concrete easily poured into molds and fit well into rebar without the separation.