### Mix Design of M-40 Grade cement concrete

The basic mix design of M-40 Grade of cement concrete by using chemical admixture provided here is for ready reference and study purpose only. Actual site conditions it may vary and thus this should be adjusted as per the location and other factors of concrete ingredients.

Parameters for mix design M40 grade of cement concrete

Type of cement used = O.P.C-43 grade
Brand of cement = coromondal
Sp. Gravity Cement material= 3.15
Fine Aggregate specific gravity = 2.61
Coarse Aggregate specific gravity (20mm) = 2.65
Coarse Aggregate specific gravity (10mm) = 2.66
Minimum Cement content = 400 kg / m3
Maximum water cement ratio assumed = 0.45

Mix Design Calculation: –

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

2. Selection of water cement ratio for concrete mixes:-
Assume the water cement ratio = 0.4

3. Calculation of cement content in concrete: –
Assume cement content in concrete 400 kg / m3

4. Calculation of water content in concrete: –
400 X 0.4 = 160 kg Which is less than 186 kg

5. Calculation of C.A. & F.A. Quantity: –

V = [ W + (C/Sc) + (1/p) . (fa/Sfa) ] x (1/1000)

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

Where

V = absolute total volume of fresh concrete, which is equal to the gross volume (m3) minus the volume of entrapped air in concrete ,

W = mass of water ( kg ) per m3 of cement concrete ,

C = mass of cement ( kg ) per m3 of cement concrete ,

Sc = specific gravity of cement material,

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

(fa) , (ca) = total mass of fine aggregate and coarse aggregate as (kg) per m3 of cement
Concrete respectively, and

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

For 20mm maximum size entrapped air is 2% considered .

Assume now that, 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 = 660.21kg

Consider fine aggregate Fa = 660 kg.

0.98 = [ 160 + ( 400 / 3.15 ) + ( 1 / 0.63 ) ( Ca / 2.65)] ( 1 /1000 )

=> Ca = 1168.36 kg.

Consider coarse aggregate Ca = 1168 kg.

Considering the ratio of coarse and fine aggregate 20 mm : 10mm = 0.6 : 0.4

20mm size = 701 kg .
10mm size= 467 kg .

Hence Mix Design details as per m3

Cement content as binder material= 400 kg
Water content= 160 kg
Fine Aggregate weight = 660 kg
Coarse Aggregate weight 20 mm = 701 kg
Coarse aggregate weight 10 mm = 467 kg
Admixture content = 0.6 % by weight of cement content = 2.4 kg.
Mason brand = 900 gm

Water: cement: F.A.: C.A. ratio is as follows = 0.4: 1: 1.66: 2.93

Observation are as follows: –
A. Mix was very cohesive and homogeneous evenly.
B. Slump value = 110mm
C. No. of cement concrete cube casted = 12 Nos.
7 days average compressive strength of cement concrete cube = 52.26MPa.
28 days average compressive strength of cement concrete = 61.95 MPa which is greater than 48.25MPa

Hence the M 40 grade mix design is accepted.