Nominal Mix Concrete Vs Design Mix Concrete in detail

Nominal Mix Concrete is prepared the the prescribed Concrete Mix Ratios, whereas the Design Mix Concrete is prepared through the rules and procedures given in IS10262(2009) Mix design codebook. Let us look in detail at the two types of concrete.

Different methods of preparing concrete

There are two ways to calculate the amount of cement, sand and aggregate required to produce different grades of concrete.

• Nominal Mix Method
• Design Mix Method

Concrete Prepared through the Nominal Mix method is called Nominal Mix Concrete and Concrete prepared through the Design Mix method is called Design Mix Concrete.

Nominal Mix Concrete

In the Nominal Mix method, the prescribed Nominal mix ratios are used to calculate the quantity of cement sand and aggregate required to produce different types of concrete. Nominal mix ratios are in the form of Cement: Fine Aggregate: Coarse Aggregate.

For example, the Nominal Mix Ratio of M15 concrete is 1:2:4. Therefore, for every 1 part of cement, to produce M15 grade concrete, we need 2 parts of sand and 4 parts of coarse aggregate. In other words, For every 1 pan of cement, we need 2 pans of sand and 4 pans of coarse aggregate to produce M15 grade concrete.

Design Mix concrete

In the Design Mix method, the process and rules given in the Mix Design codebook are used to calculate the quantities of materials required to produce different types of concrete. Design Mix ratios are also called Weigh ratios.

Difference in Method of Batching

Mix ratios of Nominal Mix concrete are Volumetric ratios so all the materials are measured in terms of volume (cubic meter, cubic feet). Mix ratios of Design Mix concrete are Weigh ratios hence all the materials are measured in terms of weight(kg, ton).

Difference in Place of Preparation

Nominal Mix concrete is produced in concrete mixers in small batches on the same construction site. Design Mix concrete is typically produced in large batches at Ready Mix RMC Plants.

Advantages of Using Design Mix Concrete

1. High-strength concrete and high-performance concrete design are possible
2. Concrete can be designed for a variety of environmental conditions and requirements.
3. Different varieties of concrete can be prepared such as flyash concrete, pumpable concrete etc.
4. Different properties of the materials such as moisture content, fineness, grading are considered in calculation.
5. Very accurate.
6. Cost-effective.

Advantages of using Nominal Mix Concrete over Design Mix concrete

1. They are easy to design and manufacture
2. Batching of materials is easier using pans and batching boxes.
3. This method can be easily understood by the workers and followed on the site.

Disadvantages

1. Materials calculated from the Nominal mix method are not as accurate as the Design mix method
2. Grades more than M20 cannot be designed.
3. Concrete cannot be adjusted to suit environmental or construction requirements
4. They are not as cheap as the Design mix concrete method when prepared in large quantiles.
5. High performance or High strength concrete cannot be produced.
6. It is dangerous to add compounds such as fly ash or super plasticizers because the calculation does not take these things into account.
7. Not Suitable for producing Ready Mix Concrete

Related Read:-

1. Learn why Mix Ratio of M25 Grade is NOT 1:1:2 | Engineering Blunders
2. Calculate Sand and Aggregate needed per 50kg bag of cement as per IS456 codebook