## Mix Design of Concrete

**Mix Design** of **Concrete is **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** 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 number of **materials** such as **cement **makes the project construction **economical**.

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

**Concrete Mix Design Example**

**Following is a Mix Design of Concrete example**

**Data Required Mix Design**

**i.** **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 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 conditions.**

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

## Mix Design of Concrete Procedure

**The following steps are to be followed for concrete mix design calculation,**

**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 the **water-cement** ratio as **0.50** for the **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** is 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} **Refer to IS 456 – 2000,**Table 5- Minimum cement
**Content**required for**mild exposure**condition =**300 kg/m3** **383.2 kg/m3 > 300 kg/m3**, hence, OK.- This value is
**required**to be checked for**durability requirements**from IS: 456 – 2000 - In this example for
**mild exposure**and for**reinforced concrete**, the**minimum**cement content is 300 kg/m3 which is**less than 383.2 kg/m**Hence cement content^{3}.**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 to 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 of 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 **

** The volume of concrete is taken = 1 m ^{3}**

**Volume 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 the**lab & to check its properties.- It will satisfy
**durability**& economy. - For making trial -1, a 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 a saturated surface **dry condition**, therefore **no correction** is **required**.

**Step-8 Concrete Trail Mixes**

**Concrete Trial Mix 1**

- The
**mix proportion**is 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 a**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 a **target strength of **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**With a^{3}**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

### What are the requirements of concrete mix design?

Requirements for 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 as per IS: 456

6. Type of exposure Condition of concrete

7. Type of cement used

**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 finding out the required proportions with the object of producing concrete of certain minimum strength and durability as economically as possible.

### 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**.

### 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

### What is the 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 of around 20 mm, whose workability lies within 50-75 mm and is categorized under the type ‘good degree of supervision.

### 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 with **Cement**: Sand: Coarse Gravel.

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Bhushan MahajanConcrete Mix Design