This document provides details on designing a concrete mix with a characteristic compressive strength of 35 MPa at 28 days. The mix uses M35 grade cement, medium sand, and a coarse aggregate of 20mm angular gravel mixed with 10mm gravel in a 70:30 ratio. The mix design calculations determine a water-cement ratio of 0.40, a cement content of 370 kg/m3, and aggregate contents of 1150 kg/m3 for 20mm gravel and 345 kg/m3 for 10mm gravel. The final concrete mix is specified with weight proportions of cement, water, fine aggregate, 20mm coarse aggregate, 10mm coarse aggregate, and admixture.

1. DESIGN OF M35 GRADE CONCRETE:
Design the concrete mix by using IS Method for the following required data:
 Characteristic compressive strength required at the end of 28 days=35N/mm2
 Maximum site or aggregate =20mm
 Shape coarse aggregate =Angular
 Degree of workability = 0.75
 Degree of quality control = good
 Degree exposure = Moderate
Data on materials
Cement used = M35 grade
Specific gravity of cement = 3.15
Coarse aggregate=20mm and 10min mixed in the ratio 70:30
Sand=conforming zone- 2(medium sand)
Assumptions:-
Specific gravity of coarse aggregate- 2.77
Specific gravity of sand -2.42
Free surface moisture
Coarse aggregate= Nil
Sand=1.0%
Water absorption Sand = Nil
Design
Step- 1 standard deviation
Pick up the standard deviation from table- 1 of IS 10262: 2009. Standard deviation is 5.0.
Step- 2 Target strength
Target strength = 𝑓𝑐𝑘 + (1.65×standard deviation)
= 35+ (1.65× 5.0)
= 43.25
𝑵
𝒎𝒎 𝟐
Step -3 water cement ratio

2. For the required target strength Find out water cement ratio from IS 456:2000 table-5. Assume
water cement ratio based on experiences is 0.40.
Step -4 maximum water cement ratio
From the table, the maximum water cement ratio for severe exposure is 0.45 so adopt w/c of
0.40
Step-5 water content
From table -2 maximum water content= 186 liter for 20 to 50 mm slump range for 20mm
Aggregate.
Required water cement is = 186 + 186×6/100
= 197.00 liters
Based on the trials with super plasticizers water content reduction achieved up to 25%.
Water content = 0.75 x 197.00
= 148.0 lit
Step-6 cement content
Determination of cement content having known the water cement ratio as 0.40 and water
contents 148.0 liters per cu. Mt.
I.e. w/c ratio= 0.40
Water content= 148.0
Cement content= 148 /0.40= 370 kg
Step-7 minimum cement content
Check for minimum cement content as per table no. 5 of IS 456:2000 for durability criteria for
severe exposure is 320 kg/m3. Hence, the worked out cement content satisfies the condition
therefore adopt cement content as 370 kg.
Step -8 coarse and fine aggregate
Determination of coarse and fine aggregate content:
V=1.0
W = 148 lit
C = 370 kg
Sfa - 2.42
Sca - 2.72

3. fa = ? & Ca=?
From table-3 volume of C.A. corresponding 20mm size aggregate and F.A. (zone 2) for w/ c
ratio of 0.5 >0.6
In our case w/c ratio =0.40 therefore C.A. volume is required to he increased or to decrease the
F.A. content. As w/ c ratio lower by 0.1, the proportion of volume of C.A. is increased by 0.02.
Corrected coarse aggregate volume = .62 + .02 = .64
For pumpable concrete and R.C.C this value should be reduced by 10%
Volume of-C.A. = 0.58
Volume of F.A = 1 - .58 = 0.42
Step-9 Mix calculations
1. Volume of concrete = 1m3
2. Volume of cement = Mass of cement
Sp.gr. of cement x 1000
= 370
3.15×1000
= 0.117m3
3. Volume of water = mass of water
Sp.gr: of water x 1000
=148
1×1000
=0.148 m3.
4. Volume of chemical admixture # Super plasticizers @ 1 to 2% by mass of cementitious
material Therefore take 1.5% = mass of admixture/ (Sp.gr of admixture *1000)
=7.4/ (1.145×1000)
=0.006m3.
5. Volume of all aggregate = 1-(0.117-0.148-0.006) = 0.729
6. Mass of CA = 0.729× volume of CA × Sp Gr. Of CA × 1000
=0.729 × .58 × 2.72 × 1000
=1150.00 kg

4. 7. Mass of FA = 0.729×volume of FA × Sp Gr. Of FA × 1000
=0.729×0.42×2.42×1000
=740.95 kg
Step 10: Weight proportions, ratio proportions
Total cubes: 14 volume of cube: 0.003375 m3
Total no of cylinder: 6 volume of cylinder: 0.0053 m3
Total conc. in 0.08m3
 Proportion by weight: (Kg)
cement water F.A 20mm C.A 10mm C.A admixture
29.60 kg 11.84 lit 59.28 kg 64.4 kg 27.60 kg 480 ml
For CA = 20mm and 10mm ratio 70:30
Fraction I =1150 ×0.7 = 805 kg
Fraction II =1150 ×0.3 = 345 kg
 Proportion by ratio:
cement water F.A 20mm C.A 10mm C.A
1 0.40 2.002 2.17 0.93