The mix design M-40 grade for Pier (Using Admixture – Fosroc) provided here is for reference purpose only. Actual site conditions vary and thus this should be adjusted as per the location and other factors.

**Parameters for mix design M40**

Grade Designation = M-40

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

Brand of cement = Vikram ( Grasim )

Admixture = Fosroc ( Conplast SP 430 G8M )

Fine Aggregate = Zone-II

Sp. Gravity Cement = 3.15

Fine Aggregate = 2.61

Coarse Aggregate (20mm) = 2.65

Coarse Aggregate (10mm) = 2.66

Minimum Cement (As per contract) = 400 kg / m^{3}

Maximum water cement ratio (As per contract) = 0.45

**Mix Calculation: -**

1. Target Mean Strength = 40 + (5 X 1.65) = 48.25 Mpa

2. *Selection of water cement ratio:-*

Assume water cement ratio = 0.4

3. *Calculation of cement content: -*

Assume cement content 400 kg / m^{3}

(As per contract Minimum cement content 400 kg / m^{3})

4. *Calculation of water: -*

400 X 0.4 = 160 kg Which is less than 186 kg (As per Table No. 4, IS: 10262)

Hence o.k.

5. Calculation for C.A. & F.A.: – As per IS : 10262 , Cl. No. 3.5.1

V = [ W + (C/S_{c}) + (1/p) . (f_{a}/S_{fa}) ] x (1/1000)

V = [ W + (C/S_{c}) + {1/(1-p)} . (ca/S_{ca}) ] x (1/1000)

Where

V = absolute volume of fresh concrete, which is equal to gross volume (m^{3}) minus the volume of entrapped air ,

W = mass of water ( kg ) per m^{3} of concrete ,

C = mass of cement ( kg ) per m^{3} of concrete ,

S_{c} = specific gravity of cement,

(p) = Ratio of fine aggregate to total aggregate by absolute volume ,

(fa) , (ca) = total mass of fine aggregate and coarse aggregate (kg) per m^{3} of

Concrete respectively, and

Sfa , Sca = specific gravities of saturated surface dry fine aggregate and Coarse aggregate respectively.

As per Table No. 3 , IS-10262, for 20mm maximum size entrapped air is 2% .

Assume F.A. by % of volume of total aggregate = 36.5 %

0.98 = [ 160 + ( 400 / 3.15 ) + ( 1 / 0.365 ) ( Fa / 2.61 )] ( 1 /1000 )

=> Fa = 660.2 kg

Say Fa = 660 kg.

0.98 = [ 160 + ( 400 / 3.15 ) + ( 1 / 0.635 ) ( Ca / 2.655 )] ( 1 /1000 )

=> Ca = 1168.37 kg.

Say Ca = 1168 kg.

**Considering 20 mm : 10mm = 0.6 : 0.4**

20mm = 701 kg .

10mm = 467 kg .

Hence Mix details per m^{3}

Cement = 400 kg

Water = 160 kg

Fine aggregate = 660 kg

Coarse aggregate 20 mm = 701 kg

Coarse aggregate 10 mm = 467 kg

Admixture = 0.6 % by weight of cement = 2.4 kg.

Recron 3S = 900 gm

**Water: cement: F.A.: C.A. = 0.4: 1: 1.65: 2.92 **

**Observation: –**

A. Mix was cohesive and homogeneous.

B. Slump = 110mm

C. No. of cube casted = 12 Nos.

7 days average compressive strength = 51.26 MPa.

28 days average compressive strength = 62.96 MPa which is greater than 48.25MPa

Hence the mix is accepted.

We are thankful to Er Gurjeet Singh for this valuable information.