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**What Is Mix Design of Concrete?**

**Mix Design** of **Concrete** i**s** the process of determining the right proportions of **cement, sand, and aggregates **for concrete to achieve the target strength of concrete.

The Advantage of **concrete mix design calculations pdf** is that it gives the right proportions of materials, thus making the concrete use economical in achieving the required strength of structural members.

As, the quantity of concrete required for huge, constructions are huge, the economy in the quantity of materials such as cement makes the project construction economical.

There different concrete mix design ratios used in the design. **Concrete Mix design** calculations for the M25 grade of concrete can be calculated from the following steps:

**Read More:** **Concrete Mix Design as Per IS Code -10262: 2019(Excel Software)**

**Also See:** **Concrete Mix Design Calculator**

**Mix Design of Concrete**

**Mix Design of Concrete IS Code IS 10262**. It is used for concrete mix design of various grades of concrete.

Following is a **concrete mix design example,**

**Data Required for Concrete Mix Design**

**i.** **Concrete Mix Design Data**

(a) Characteristic compressive strength of concrete required at end of 28 days = M 25

(b) Nominal maximum size of aggregate used = 20 mm

(c) Shape of Coarse Aggregate = Angular

(d) Required workability at site = 50-75 mm (slump Value)

(e) Quality control is done by as per IS: 456

(f) Type of exposure Condition of concrete (as defined in IS: 456) = Mild

(g) Type of cement used = PSC conforming IS: 456 – 2000

(h) Method of placing Concrete on Site = pumpable concrete

**(ii) Material testing data (determined in the laboratory)**

(a) Specific gravity of cement = 3.15

(b) Specific gravity of FA = 2.64

(c) Specific gravity of CA = 2.84

(d) Aggregates are assumed to be having surface dry condition.

(e) Fine aggregates are confirm to Zone II of IS – 383

## Mix Design of Concrete Procedure

Following are concrete mix design steps and some of the important concrete mix design formula;.

**Step 1: Determining the Target Strength of Concrete**

Himsworth constant for 5% risk factor is 1.65 & standard deviation is taken from IS: 456 2000 for M – 25 Grade of concrete is 4.0.

**f**_{target}** = f**_{ck}** + 1.65 x S**

**= 25 + 1.65 x 4.0 = 31.6 N/mm**^{2}

Where,

S = Standard Deviation (N/mm^{2}) = 4 (Refer: IS 10262- 2009 table -1)

**Step 2: Determining Water-Cement ratio**

**Refer: IS 456, (page no 20) Table 5**

Maximum water-cement ratio taken for Mild exposure condition = 0.55

Assume water-cement ratio as 0.50 for experiment base

**0.5 < 0.55, hence it is OK.**

**Read More: Concrete Mix Design Calculations and Its Ratio for M 25 Grade**

**Step 3: Selection of Water Content for Mix**

**Refer: IS 10262- 2009 Table 2**

Maximum water content taken = 186 Kg (maximum size of aggregate = 20 mm)Correction in water content is

Estimated water content for mix = 186+ (3/100) x 186 = 191.6 kg
/m^{3}

#### Step 4 : Selection of Cement Content for Mix

- Water-cement ratio = 0.50
- Corrected water content for mix = 191.6 kg /m
^{3} - Cement content =
- Refer IS 456 – 2000, Table 5
- Minimum cement Content required for mild exposure condition = 300 kg/m
^{3} - 383.2 kg/m
^{3 }> 300 kg/m^{3}, hence, OK. - This value is required to be checked for durability requirement from IS: 456 – 2000
- In this example for mild exposure and for the reinforced concrete the minimum cement content is 300 kg/m
^{3}which are less than 383.2 kg/m^{3}. Hence cement content adopted = 383.2 kg/m^{3}. - IS: 456: 2000, clause 8.2.4.2
- Maximum cement content for mix = 450 kg/m
^{3}.

**Read More : Building Estimation Excel Sheet Free Download**

**Step 5: Estimation of Coarse Aggregate Proportion for Mix **

**Refer IS 10262- 2009, Table 3**

- For Nominal max. size of aggregate for mix = 20 mm,
- Zone of fine aggregate = Zone II
- And For w/c = 0.5
- The volume of coarse aggregate per unit volume Concrete = 0.62

**Table for Correction in Estimation of Coarse Aggregate Proportion**

**(Note 1:** For every ±0.05 increase or decrease change in w/c, the coarse aggregate proportion is to be changed by 0.01. If the w/c is less than 0.5, the volume of coarse aggregate is required to be increased to reduce the fine aggregate content in the mix. If the water-cement ratio is more than 0.5, the volume of coarse aggregate is to be reduced to increase the fine aggregate content. If the coarse aggregate is not of an angular shape, the volume of coarse aggregate is required to be increased suitably, based on experience-based.

**(Note 2:** For pumpable concrete or congested reinforcement in structure the coarse aggregate proportion may be reduced up to 10%**)**

Hence,Volume of coarse aggregate per unit volume of total Volume of concrete = 0.62 x 90% = 0.558

Volume of fine aggregate in mix = 1 – 0.558 = 0.442

**Step 6: Estimation of the Mix Materials **

- Volume of concrete is taken = 1 m
^{3} - bVolume of cement = (Weight of cement / Specific gravity of cement) x (1/100) = (383.2/3.15) x (1/1000) = 0.122 m
^{3} - Volume of water = (Weight of water / Specific gravity of water) x (1/1000)
- = (191.6/1) x (1/1000) = 0.1916 m
^{3} - Volume of aggregates = a – (b + c ) = 1 – (0.122 + 0.1916) = 0.6864 m
^{3} - Weight of coarse aggregates = 0.6864 x 0.558 x 2.84 x 1000 = 1087.75 kg/m
^{3} - Weight of fine aggregates = 0.6864 x 0.442 x 2.64 x 1000 = 800.94 kg/m
^{3}

**Concrete Mix Proportions for Concrete Trial Mix -1**

- Cement = 383.2 kg/m
^{3} - Water = 191.6 kg/m
^{3} - Fine aggregates = 800.94 kg/m
^{3} - Coarse aggregate = 1087.75 kg/m
^{3} - W/c = 0.5
- For trial -1 of concrete in lab & to check its properties.
- It will satisfy durability & economy.
- For making trial -1, mass of ingredients required will be calculated for 4 no’s cube assuming 25% wastage.
- Volume of concrete required for Making 4 cubes = 4 x (0.15
^{3 }x1.25) = 0.016878 m^{3} - Wt. of Cement = (383.2 x 0.016878) kg/m
^{3}= 6.47 kg - Wt. of Water = (191.6 x 0.016878) kg/m
^{3}=3.23 kg - Wt. of Coarse aggregate = (1087.75 x 0.016878) kg/m
^{3}=18.36 kg - Wt. of Fine aggregates = (800.94 x 0.016878) kg/m
^{3 =}13.52 kg

**Downloads: Excel Sheet for Concrete Mix Design as per is 10262-2009**

**Step 7: Correction for Absorption / Moisture of Aggregate**

As we assumed the aggregate is saturated surface dry condition, therefore no correction is required.

**Step 8: Concrete Trail Mixes**

**Concrete Trial Mix 1**

- The mix proportion determined in Step 6 Make trial mix -1 & with this proportion, concrete is manufactured and tested for fresh concrete properties requirements like workability, bleeding, and finishing qualities.
- In this Trial Mix,
- Slump value = 25 mm
- Compaction Factor = 0.844
- From the Mix Slum test, the concrete is workable and had a true slump of about 25 mm and it is free from segregation and bleeding.
- required slump = 50-75 mm
- So modifications and changes are needed in trial mix 1 to get the desired workability.

**Concrete Trial Mix 2**

- To increase the workability of concrete mix from 25 mm to 50-75 mm an increase in water content by +3% is to be made.
- The corrected water content for mix = 191.6 x 1.03 = 197.4 kg.
- As mentioned earlier to adjust fresh concrete properties the water cement ratio should not be changed. Hence
**Cement Content = (197.4/0.5) = 394.8 kg/m**^{3}- Which also need to satisfy durability requirement.
- Volume of aggregate in Concrete = 1 – [{394.8/(3.15×1000)} + {197.4/(1 x 1000)}] = 0.6773 m
^{3} - Weight of coarse aggregate = 0.6773 x 0.558 x 2.84 x 1000 = 1073.33 kg/m
^{3} - Weight of fine aggregate = 0.6773 x 0.442 x 2.64 x 1000 = 790.3 kg/m
^{3}

**Concrete Mix Proportions for Trial Mix 2**

- Weight of Cement = 384.8 kg/m
^{3} - Weight of Water = 197.4 kg/m
^{3} - Weight of Fine aggregate =790.3 kg/m
^{3} - Weight of Coarse aggregate = 1073.33 kg/m
^{3} - For making trial -2, the Weight of material required will be calculated for 4 no’s cube assuming 25% wastage.
- Volume of concrete required for 4 cubecasting = 4 x (0.153 x1.25) = 0.016878 m3
- Weight of Cement = (384.8 x 0.016878) kg/m3 = 6.66 kg
- Weight of Water = (197.4 x 0.016878) kg/m3 =3.33 kg
- Weight of Coarse aggregate = (1073.33 x 0.016878) kg/m3 =18.11 kg
- Weight of Fine aggregates = (790.3 x 0.016878) kg/m3 = 13.34 kg
- In this trial Mix,
- Slump value for mix = 60 mm
- Compaction Factor for mix = 0.852
- So, from the results of the slump of Mix, the concrete is workable and had a true slump of about 60 mm.
- Required slump = 50-75 mm
- So, it satisfied the desired workability by satisfying the requirement of 50-75 mm slump value.
- Now, we have to go for trial mix-3

**Concrete Trial Mix 3 **

- In this trial mix water/cement ratio is to be decreased by 10% keeping water content constant.
- Water cement ratio = 0.45
- With the reduction of 0.05 in w/c, we have to increase of coarse aggregate fraction by 0.01.
- Coarse aggregate fraction in mix = 0.558 +0.01 =0.568
- W/c = 0.45 and water content for mix = 197.4 kg/m
^{3} - Cement content for mix = (197.4/0.45) = 438.7 kg/m
^{3} - Volume aggregate in total volume of concrete = 1 – [{438.7/(3.15 x 1000)} + (197.4/1000)] = 0.664 m
^{3} - Weight of coarse aggregate = 0.664 x 0.568 x 2.84 x 1000 = 1071.11 kg/m
^{3} - Weight of fine aggregate = 0.664 x 0.432 x 2.64 x 1000 = 757.28 kg/m
^{3}

## M 25 Mix Design of Concrete

For the Compressive Strength of concrete vs. C/W graph for target strength 31.6 MPa, we found

**Water cement ratio = 0.44****Weight of water content**=**197.4 kg/m**^{3}**Weight of Cement content**= (197.4/0.44) =**448.6 kg/m**^{3}- Volume of aggregate in total volume of concrete = 1 – [{448.6/(3.15 x 1000)} + (197.4/1000)] =
**0.660 m**^{3} - A
**reduction of 0.05 in w/c**, we have to increase of coarse aggregate fraction**by 0.01.** **Coarse aggregate volume**= 0.558 +0.01 =**0.568 m**^{3}**Volume of fine aggregate in mix**= 1 – 0.568 =**0.432****m**^{3}**Weight of coarse aggregate =**0.660 x 0.568 x 2.84 x 1000 =**1064.65 kg/m**^{3}**Weight of fine aggregate =**0.660 x 0.432 x 2.64 x 1000 =**752.71 kg/m**^{3}

**Download Mix Design of ****Concrete** pdf (M25 Grade)

**Concrete**pdf (M25 Grade)

**Download Concrete Mix Design Excel Sheet**

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## FAQs

### Q.1 What are the requirements of concrete mix design?

Requirements of concrete mix design are listed below:

1. Characteristic compressive strength of concrete

2. Nominal maximum size of aggregate used

3. Shape of Coarse Aggregate

4. Required workability at site

5. Quality control is done by as per IS: 456

6. Type of exposure Condition of concrete

7. Type of cement used

### Q.2 **What is Concrete Mix Design?**

**Mix Design of Concrete** can be defined as the method of calculating a suitable quantity of materials of concrete and find out the required proportions with the object of producing concrete of certain minimum strength and durability as economically as possible.

### Q.3 What is IS code for concrete mix design?

The Bureau of Indian Standards recommended a set procedure for the design of concrete mix mainly based on the work done in national laboratories. The **Concrete Mix Design Calculation** procedure is covered in** IS 10262: 2019**.

### Q.4 How is concrete mix design calculated?

**The following Steps Should be followed to calculate Concrete Mix Design:****Step 1:** Determining the Target Strength of Concrete**Step 2 **Determining Water-Cement ratio**Step 3: **Selection of Water Content and Cement Content for Mix**Step 4**: Estimation of Coarse Aggregate Proportion for Mix**Step 5: **Correction for Absorption and Concrete Trail Mixes

### Q.5 What is M25 concrete mix design?

**M-25 MIX DESIGNS (as per IS-10262-2009):**

M25 is a grade designation, having a Maximum nominal crushed angular aggregate size around 20 mm, whose workability lies within 50-75 mm and is categorized under the type ‘good degree of supervision.

### Q.6 What is the strongest concrete mix ratio?

**Concrete Mix Ratio of 1:3:5**,

Concrete Mix Ratio 1:3:5 is considered to be a strong concrete mix design. Where 1:3:5 complies **Cement**: Sand: Coarse Gravel.

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