Difference between Nominal Mix Concrete and Design Mix

There are two types of concrete mixes used for construction. They are Design mix concrete and nominal mix concrete. Both types of concrete mixes have their own advantages and disadvantages.

Design Mix Concrete

Design Mix Concrete is prepared by using step by step procedure given in IS10262(2009) with reference to IS456(2012) codebook.

Pros

1. Cement sand and aggregate are calculated in terms of weight(kg)
2. Quantities are can be adjusted to suit different environmental conditions.
3. Different types of concrete can be designed for different construction needs
4. High strength concrete and high-performance concrete can be designed
5. Calculated quantities are more accurate than Nominal Mix Concrete method
6. They are cost-effective

Cons

1. Designing requires a deeper understanding and elaborate calculation
2. Time-consuming if the concrete batch is in smaller amounts.
3. Workers may find this method difficult to understand.

Read:- Simple Mix Design of M30 grade concrete with Mineral Admixture and superplasticizers.

Nominal Mix Concrete

Nominal Mix Concrete is prepared by using Concrete Mix Ratios or from the Weight Approximations given in the codebook.

In the Concrete Mix ratio method, quantities are calculated in terms of volume. They can be later converted to kg, cubic feet and other units as required by multiplying with bulk densities of the materials and conversion factor

In the weight approximation method, the quantity of sand and aggregate are directly calculated in terms of weight (kg) per 50kg cement bag using IS456.

Water content required to produce Nominal Mix concrete is given in the IS456 codebook.

Pros

1. Nominal mix concrete is easier to design
2. Batching of materials are easier in the construction site using pans and batching boxes.
3. They are often used to produce smaller to medium level of concrete batches from M5 to M20 grade concrete.
4. Workers can easily understand and follow this method on site.

Cons

1. Materials calculated from the Nominal Mix method are not as accurate as the Design Mix Method
2. They are only suitable to produce smaller batches from M5 to M20 grade concrete.
3. Quantities cannot be adjusted to suit environmental or construction needs
4. They are not as cost-effective as Design mix concrete method. Since quantities are not accurate more cement to ensure safety and to get target strenth
5. High performance or High strength concrete cannot be produced.
6. Adding any admixtures like fly ash or superplasticizers is risky as calculation does not take these things into account.
7. Not Suitable for producing Ready Mix Concrete

Read:- Learn simple methods to Calculate Cement Sand and Aggregate needed for concrete in volume and weight

https://civilbaselife.blogspot.com/2020/04/cement-sand-and-aggregate-needed-for.html

Er.SP.ASWINPALANIAPPAN.,M.E.,(Strut/.,)

Structural Engineer

Madras Terrace Architectural Works

www.civilbaselife.blogspot.in