Many concrete mixes are not balanced properly. As a result, they often display greater tendencies to shrink, are more difficult to finish, or are more difficult to pump. Concrete mixes with proportions that are properly balanced are placed, consolidated, and finished easily. A balanced concrete mix is not an accident. The process of developing a balanced concrete mix is clear and well-known. The first step is understanding what is meant by a balanced concrete mix.
A balanced concrete mix is one in which all of the ingredients are combined in proportions relative to each other so that the mix will provide the most desirable fresh and hardened concrete properties. Properties of a balanced mix include: optimum water demand, maximized compressive strength, greatest possible benefits from admixtures, easy placement and consolidation, and densest configuration after consolidation. It is not possible to develop a mix design that will apply in every location throughout the country. Raw materials and admixtures used in different locations vary significantly. Instead, specific considerations associated with each application must be explored.
Some of these considerations include various properties of the following: cement, aggregates, fly ash, silica fume, chemical admixtures, production facilities and past history.