Concrete Mix Design – Why is it required?

Concrete Mix design is the process of preparing Concrete of desired strength and durability with suitable proportioning ingredients. Each ingredients have their own properties so it is tough task to make economical and good concrete mix. The concrete mix design allows an engineer or a construction professional to design the concrete according to the specifications & the requirements of the proposed structure.

An appropriate and ideally formulated concrete is prepared using the right mix design, which enhances the properties of the structure, ensuring a good strength and stability to it. As we are aware, the mix design are of two types. Nominal mix and designed mix. The Nominal mix is basically applied to the concrete preparation for normal structures, whereas, the design mix is used when special structures or the structures with higher strength requirements are to be built.

Let us learn about different types of concrete mix designs in detail, below.

Types of Concrete Mix Design

Concrete mix design can be done by the two ways namely

• Nominal concrete mix
• Designed concrete mix

Nominal Concrete Mix

It is the nominal concrete mix with lower strength used for small and unimportant works. In this type fine aggregate quantity is fixed irrespective of cement and coarse aggregate proportions. Hence, the quality of concrete mix will be varied and required strength may not be obtained. Water-Cement ratio is also not specified so lower grade concrete below M20 is prepared by this way but higher grade concrete must be prepare with designed concrete mix method.

Designed Concrete Mix

This design is done in order to get the required strength of concrete. There is no such proportions are derived. Thus we can get the desired properties either in the fresh stage or in the hardened stage.

The fresh concrete properties like workability, setting time and hardened concrete properties like compressive strength, durability etc. can be get by this method. Use of additives like admixtures, retarders etc. other than basic ingredients are used to improve the properties of mix.

Using design concrete mix, we can design various grades of concrete from as low as M10 grade to higher grades such as M80, M100 can also be prepared. Each mix prepared is tested in laboratory after hardening to verify whether it meet the requirement or not.

Advantages of Concrete Mix Design

• Desired Proportions of Each ingredient: We can get desired proportion of each ingredients which are cement, coarse aggregate, fine aggregate, water etc. to obtain the required properties of resulting mix.
• Quality Concrete Mix: While testing quality of ingredients will be known and this will help in the Concrete mix. Concrete with good quality improves its properties such as strength, durability etc.?
• Economical Concrete Mix: using concrete mix design, concrete of required strength can be designed with accurate quantity of cement. It saves the cost of the project and economical concrete mix will be obtained.
• Best Use of Locally Available Material: Concrete mix design permit the use of locally available material such as coarse aggregates, fine aggregates etc. only if it is of good quality. This will reduce the cost of project and will also encourage rapid construction.
• Desired Properties of Mix: The concrete obtained through mix design contain desired properties like workability, durability, setting time, strength, impermeability etc. The design is processed by considering some important factors like water cement ratio, gradation of aggregates etc.