**Concrete** is the most extensively
material composed of cement,sand,coarse and fine aggregates with is mixed with
water thats in turn hardens. During the formation of concrete mix we can add
plasticizers whether they are accelerating/retarding plasticizers which depends
on the design mix considerations.Morever, temperature is the important factor
which can effect the concrete and the mix design should have a good quality
with high performance.The desired properties of structure is achieved by
economical extensively concrete mix.

**Difference between Nominal mix and Design mix of concrete:**

**DESIGN MIX-**

is defined as the process of selecting the appropriate components of concrete and determining their relative proportions with the aim of producing concrete of as little strength and durability as possible economically.

There are many grade of design mix concrete like M-25, M-30, M-35 andM-40 etc.

M-25
1:1:2

M-30 1:1.5:2.8

M-35 1:1.53:2.88

M-40 1:1.74:2.75.

The above mix designs M-30,33,40 are designed as per the reqirement of the
project which includes cost rates with the contractor.

In above grades of concrete mix the letter 'M' refers to Mix where as the
value like 25,30,35 and 40 etc indicates the compressive characteristic
strength of concrete after 28 days considering suitable conditios. Unit of this
compressive characteristic strength of concrete is Newton /mm^{2}

1. Design mix is a mix in which all the proportions of the mix are considered in terms of weight where the stable cost of concrete can be reduced.

2. It is performance oriented concrete.

3. It is adopted for
high grade concrete.

4. It has quality control.

5. The ratio of water grade based on concrete grade and concrete's 28-day compressive strength and strength of concrete.Water content can be modified keeping in view the compression factor value (laboratory based test).

6. Material considered to be the maximum size according to the aggregate.

7. Plasticizers can also be used for good workability while
pumping through concrete in the batching plant.

8. Mixing time can be kept standard and if required can be changed as per the
need due to temperature effects

**NOMINAL MIX- **

specifies the fix or standard arbitary
proportion of the cement, sand and aggregates.

There are many grade of nominal mix concrete
like M-5, M-7.5, M-10, M-15 and M-20.

The ratio of various grade of concrete is being given below -

M-5 1:5:10

M-7.5 1:4:8

M-10 1:3:6

M-15 1:2:4

M-20 1:1.5:3

For
example –

For M-5 We can say :1(cement):5(fine aggregate or sand) :10(coarse aggregate).

In
above grades of concrete mix the letter 'M' refers to Mix where as the
value like 5,7.5,10,15 etc indicates the compressive characteristic strength of
concrete after 28 days in specified conditions. Unit of this compressive
characteristic strength of concrete is Newton /mm^{2}

1.The nominal mixture is a volume in which all the volume ratios are considered
where the strength and cost of concrete vary.

2. It is used in ordinary concrete which includes concrete grade which does not exceed M-20.

3. Quality control is not required.

4.Such type of concrete mix is generally used in small quantity or where load is not high.

5. The ratio of water
cement to stability is based on quality, experience and practical test.

6. Water content can be changed by slow cost (field based test).

7. Mixing time - concrete mixers rotate at a minimum rate of 15
rpm, mixing time required to produce 1 batch of concrete is
2 minutes.

2bags

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