Write a 4000 word paper answering; The properties of concrete usually depend on the mix proportions as well as the placing and curing methods. It is a common practice for designers, when determining structural dimensions, to either specify or assume a specific strength or modulus of elasticity of the concrete. It is the responsibility of the materials engineer to ensure that the concrete is proportioned, mixed, placed, and cured in a proper way so as to bear the properties that the designer specified. The properties of the concrete mix in both the solid and plastic states are affected by its proportioning.
The materials engineer is often concerned with the workability as well as the finishing characteristics of the concrete during the plastic state. Some of the properties of hardened concrete which are important to material engineer include the strength, durability, porosity and modulus of elasticity. Generally, strength is the controlling design factor. Concrete strength often refers to the average (mean) compressive strength of three tests unless stated otherwise. Each of the three tests is the average (mean) result of two separate cylinders which are tested in compression after curing for a duration of 28 days. According to
Over the years, there has been the development of various mix design methods which range from an arbitrary volume method of cement, sand: and coarse aggregate in the ratio of 1:2:3 respectively to the weight and absolute volume methods which has been put in place by the American Concrete
Institute’s Committee 211. The weight method, which uses a known or assumed unit of weight concrete, provides techniques that are relatively simple in order to estimate mix proportions. The absolute volume method employs the specific gravity for each of the ingredients so as to calculate the unit volume that each will occupy within a unit volume of concrete. .