**M 50 Grade of concrete Mix Design**

From the concept of concrete technology the concrete mix design M-50 grade (Using Admixture – poly carboxylate base) provided here in this context is for reference purpose and experimental purposes only. Actual site mixing condition vary and so that, this should be adjusted as per the location , environment, material properties, workmanship and other factors or parameters.All the data and output result are based on laboratory based experiment and concrete mix analysis.

**Parameters for concrete mix design M50 grade of concrete**

Grade of Concrete = M-50

Type of cement are used = O.P.C-43 grade

Brand of cement = Local Brand

Admixture = Poly Carboxylate based admixture

Fine Aggregate = Zone-II graded sand

**Sp. Gravity**

Cement = 3.16

Fine Aggregate = 2.62

Coarse Aggregate (20mm) = 2.64

Coarse Aggregate (10mm) = 2.65

Minimum Cement content in concrete mix =400 kg / m3

Maximum water cement ratio to be used in concrete mix = 0.45

**Mix Design Calculation: –**

**1. Target Mean Strength of concrete = 50 + ( 5 X 1.65 ) = 58.25 Mpa**

**2. ****Selection of water cement ratio for mix design of concrete :-**

Assume water cement ratio to be used in ths particular mix design = 0.35

**3. Calculation of water: –**

Approximate water content for 20 mm max. Size of aggregate in concrete mix is = 180 kg /m3 .

As plasticizer type of admixture was used in this experiment so, reduction of water content may be assumed by 20%.

Now after reduction net water content = 180 X 0.8 = 144 kg /m3

**4. ****Calculation of cement content in concrete mix:-**

Water cement ratio in proposed concrete mix design = 0.35

Water content to be used per cum of concrete = 144 kg

Cement content used in concrete mix = 144/0.35 = 411.4 kg / m3

Say cement content in concrete mix = 412 kg / m3 (As per consideration Minimum cement content 400 kg / m3 )

Hence it is O.K.

**5. Calculation for quantity of C.A. & F.A.: **

Volume of concrete taken in mix design = 1 m3

Volume of cement for mix design = 412 / ( 3.16 X 1000 ) = 0.1308 m3

Volume of water in mix design = 144 / ( 1 X 1000 ) = 0.1440 m3

Volume of Admixture in mix design= 4.995 / (1.145 X 1000 ) = 0.0043 m3

Total weight of other materials except coarse aggregate in concrete mix design = 0.1308 + 0.1440 +0.0043 = 0.2791 m3

Volume of coarse and fine aggregate = 1 – 0.2791 = 0.7209 m3

Volume of F.A. In concrete mix design = 0.7209 X 0.33 = 0.2379 m3 (Assuming that 33% by volume of total aggregate )

Volume of C.A. In concrete mix design = 0.7209 – 0.2379 = 0.4830 m3

Therefore weight of F.A. In concrete mix design= 0.2379 X 2.62 X 1000 = 623.298 kg/ m3

Now weight of F.A. In mix design of concrete = 621 kg/ m3

Therefore weight of C.A. in concrete mix design= 0.4830 X 2.655 X 1000 = 1282.365 kg/ m3

Say weight of C.A. = 1284 kg/ m3

Considering the ratio of coarse aggregate i.e 20 mm: 10 mm = 0.55:0.45

20 mm size aggregate quantity= 706 kg .

10 mm size aggregate quantity = 578 kg .

The cohesiveness and workability of concrete has been maintained by proper concrete test process.

Hence Mix details of M 50 grade of concrete per m3 basis volume of total mix quantity

Increasing cement, water, admixture content by 2.5% by various trial and error process,

Cement quantity= 412 X 1.025 = 422 kg

Water quantity= 144 X 1.025 = 147.65 kg

Fine aggregate quantity= 621 kg

Coarse aggregate 20 mm total quantity= 706 kg.

Coarse aggregate 10 mm quantity= 578 kg.

Admixture quantity by weight = 1.2 % by weight of cement = 5.064 kg.

**Water: cement: F.A.: C.A. = 0.35: 1: 1.473: 3.044**

**Observation: –**

Concrete Mix was cohesive and homogeneous and sticky in nature.

Slump test value result of concrete mixes = 120 mm

Total No. of concrete cube casted = 9 Nos.

7 days average compressive strength of concrete cube= 53.07 MPa.

28 days average compressive strength of concrete cube = 63.52 MPa which is greater than 58.26 MPa

Hence the concrete mix accepted and ready to use as field casting.