2. Outline
◦ Introduce the new code IS 10262 : 2019
◦ Demonstrate mix design procedure for M25 grade concrete
◦ Take away from the Presentation
3. Mix proportioning for M25 grade concrete
A-1 STIPULATIONS FOR PROPORTIONING
a) Grade designation : M25
b) Type of cement : OPC 43 Grade conforming to IS 8112
c) Maximum nominal size of aggregate : 20 mm
d) Minimum cement content and maximum water-cement ratio to be adopted and/or : Moderate (for
reinforced concrete) Exposure conditions as per Table 3 and Table 5 of IS 456
e) Workability : 75 mm (slump)
f) Method of concrete placing : Chute (Non pumpable)
g) Degree of site control : Good
h) Type of aggregate : Crushed angular aggregate
j) Maximum cement content not including fly ash : 450 kg/m3
k) Chemical admixture type : Superplasticizer – normal (If Required)
4. A-2 TEST DATA FOR MATERIALS
a) Cement used : OPC 43 Grade conforming to IS IS 269
b) Specific gravity of cement : 3.15
c) Chemical admixture : Superplasticizer conforming to IS 9103
d) Specific gravity of
1) Coarse aggregate [at saturated surface dry : 2.74 (SSD) Condition]
2) Fine aggregate [at saturated surface dry : 2.65 (SSD) Condition]
3) Chemical admixture : 1.145
e) Water absorption
1) Coarse aggregate : 0.5 percent
2) Fine aggregate : 1.0 percent
f) Moisture content of aggregate [As per IS 2386 (Part 3)]
1) Coarse aggregate : Nil
2) Fine aggregate : Nil
g) Sieve analysis: 1) Fine aggregate – Conforming to Zone II of Table 9 of IS 383
5. A-3 TARGET STRENGTH FOR MIX PROPORTIONING
f’ck = fck+1.65 S or f’ck = fck + X, whichever is higher
S = standard deviation, and X = factor based on grade of concrete
From Table 2, standard deviation, S = 4.0 N/mm2
From Table 1, X = 5.5 for M25
f’ck = 25+1.65 (4) or f’ck = 25 + 5.5
f’ck = 31.6 or f’ck = 30.5,
Take f’ck = 31.6 N/mm2
6. A-4 APPROXIMATE AIR CONTENT
From Table 3, the approximate amount of entrapped
air to be expected in normal (non-air-entrained)
concrete is 1.0 percent for 20 mm nominal maximum
size of aggregate
A-5 SELECTION OF WATER-CEMENT RATIO
Free water-cement ratio required for the target strength
of 31.6 N/mm2 is 0.46 for OPC 43 grade curve. This is
lower than the maximum value of 0.50 prescribed for
‘moderate’ exposure for reinforced concrete as per
Table 5 of IS 456.
0.46< 0.50, hence O.K.
7. A-6 SELECTION OF WATER CONTENT
From Table 4, water content = 186 kg (for 50 mm
slump) for 20 mm aggregate.
Estimated water content for 75 mm slump
= 186 + (3/100 * 186) = 191.58 kg
If superplasticizer is used, the water content may be reduced.
A-7 CALCULATION OF CEMENT CONTENT
Water-cement ratio = 0.46
Cement content = 192/0.46 = 417.39 kg/m3 ≈ 418 kg/m3
From Table 5 of IS 456, minimum cement content for ‘moderate’ exposure condition = 300 kg/m3
418 kg/m3> 300 kg/m3, hence, O.K.
8. A-8 PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGETE CONTENT
From Table 5, the proportionate volume of coarse aggregate corresponding to 20 mm size
aggregate and fine aggregate (Zone II) for water-cement ratio of 0.50 = 0.62.
9. A-8 PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGETE CONTENT
From Table 5, the proportionate volume of coarse aggregate corresponding to 20 mm size
aggregate and fine aggregate (Zone II) for water-cement ratio of 0.50 = 0.62.
In the present case water-cement ratio is 0.46. Therefore, volume of coarse aggregate is required
to be increased to decrease the fine aggregate content.
As the water-cement ratio is lower by 0.04, the proportion of volume of coarse, aggregate is
increased by 0.008 (at the rate of ± 0.01 for every ± 0.05 change in water cement ratio).
Therefore, corrected proportion of volume of coarse aggregate for the water-cement ratio of
0.46 = 0.62 + 0.008 = 0.628.
Volume of fine aggregate content = 1 – 0.628 = 0.372
10. A-9 MIX CALCULATIONS
The mix calculations per unit volume of concrete shall be as follows:
a) Total volume = 1 m3
b) Volume of entrapped air in wet concrete = 0.01 m3
c) Volume of cement =
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑜𝑜𝑜𝑜 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐
𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 𝑜𝑜𝑜𝑜 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐
∗
1
1000
=
418
3.15
∗
1
1000
= 0.133 𝑚𝑚3
d) Volume of water =
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑜𝑜𝑜𝑜 𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤
𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 𝑜𝑜𝑜𝑜 𝑤𝑤𝑤𝑤𝑡𝑡𝑒𝑒𝑒𝑒
∗
1
1000
=
192
1
∗
1
1000
= 0.192 𝑚𝑚3
e) Volume of all aggregate = [(a-b) - (c+d)] = [(1-0.01) – (0.133 + 0.192)] = 0.655 𝑚𝑚3
f) Mass of coarse aggregate = e × Volume of coarse aggregate × Specific gravity of coarse
aggregate × 1000
= 0.655 × 0.628 × 2.74 × 1000 = 1127.1 kg or 1127 kg
11. A-9 MIX CALCULATIONS
g) Mass of fine aggregate = e × Volume of fine aggregate × Specific gravity of fine aggregate
× 1000
= 0.655 × 0.378 × 2.65 × 1000 = 656.11 kg or 657 kg
A-10 MIX PROPORTIONS FOR TRIAL NUMBER 1
Cement = 418 kg/m3
Water = 192 kg/m3
Fine aggregate (SSD) = 657 kg/m3
Coarse aggregate (SSD) = 1127 kg/m3
Free water-cement ratio = 0.46
12. A-11 ADJUSTMENT ON WATER, FINE AGGREGATE AND COARSE AGGREGATE (IF THE
COARSE AND FINE AGGREGATE IS IN DRY CONDITION)
𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝐷𝐷𝐷𝐷𝐷𝐷 =
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑜𝑜𝑜𝑜 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎 𝑖𝑖𝑖𝑖 𝑆𝑆𝑆𝑆𝑆𝑆 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶
1 +
𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎
100
𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝐷𝐷𝐷𝐷𝐷𝐷 =
657
1 +
1
100
= 651 𝑘𝑘𝑘𝑘/𝑚𝑚3
𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝐷𝐷𝐷𝐷𝐷𝐷 =
𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑜𝑜𝑜𝑜 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎 𝑖𝑖𝑖𝑖 𝑆𝑆𝑆𝑆𝑆𝑆 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶
1 +
𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎
100
𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝐷𝐷𝐷𝐷𝐷𝐷 =
1127
1 +
0.5
100
= 1122 𝑘𝑘𝑘𝑘/𝑚𝑚3
The extra water is to be added for absorption by coarse and fine aggregate.
13. A-11 ADJUSTMENT ON WATER, FINE AGGREGATE AND COARSE AGGREGATE (IF THE
COARSE AND FINE AGGREGATE IS IN DRY CONDITION)
1) For coarse aggregate = Mass of coarse aggregate in SSD condition – mass of coarse aggregate
in dry condition
= 1127 – 1122 = 5 kg
2) For fine aggregate = Mass of fine aggregate in SSD condition – mass of fine aggregate in dry
condition
= 657 – 651 = 6 kg
The estimated requirement for added water, therefore, becomes
= 192 + 5 + 6 = 203 kg/m3
14. A-12 MIX PROPORTIONS AFTER ADUSTMENT
FOR DRY AGGREGATES
Cement = 418 kg/m3
Water (to be added) = 203 kg/m3
Fine aggregate (Dry) = 651 kg/m3
Coarse aggregate (Dry) = 1122 kg/m3
Free water-cement ratio = 0.46
15. Take Away from the Presentation
1. IS 10262 – 2019 code gives mix designs for Higher strength concrete mixes using
supplementary cementitious materials, Self compacting concrete and Mass concrete.
2. Durable concrete mixes can be produced from OPC 33, 43, 53 Grades and PPC / Blended
Cements.
3. Supplementary cementitious materials increases the strength and durability of concrete.
4. Water should not be added to increase workability at site. It reduces durability. Instead use
suitable water reducing admixture.
5. Lesser water cement ratio – Lower permeability - Higher durability
6. Ideal water/cement ratio – 0.34 to 0.4 from durability perspective for normal strength concrete.
7. Potable water should be used for making concrete. Check chloride and sulphate content.
8. Air-entraining admixtures required for freeze-thaw resistance. Hydration stabilizer retains wet-
concrete properties for longer duration.
9. Required Cover to concrete should be provided per IS 456.
