By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee
In India 0.93 kg of CO_{2} is emitted in the production of one kg of cement. In the financial year 200910 India produces 200 million tonnes of cement. In the production of this cement 186 million tonnes of CO_{2} was emitted in the atmosphere during financial year of 200910.
The availability of water in India per person per year in 1950 was 5177 cu.m. In the year 2009 it is reduces to 1700 cu.m.
If 50 million tonnes cement in making concrete uses water reducers 7500000 tonnes of cement can be saved. 3750000 kl of potable water will be saved and the saving of Rs. 3300 crores per year to construction industry. This amount is worked out after adjusting the cost of water reducers. Less cement used means less cement required to be produce by the cement factories resulting 6975000 tonnes of CO_{2} will be prevented to be emitted to the atmosphere. These are worked out with an average saving of 15% cement and 15% water.
CO_{2} emission is word problem, but for India in addition to CO2 it has problems of Air, Water, Soil, Food and Noise pollutions. Less densily populated countries may cope with these problems but for India it is of the top concern. The population figures of 2009 is, India 350 person per sq.km, China 132 person per sq.km and USA only 34 person per sq.km. The figures of 2006 CO¬2 emissions are USA 658.60 tonnes per sq.km, China 611.76 tonnes per sq.km and India 459.35 tonnes per sq.km. Every one should contribute his or her efforts to save the environment from pollution. Those involve in the construction activities can contribute their share by proper design of concrete Mixes. This is best illustrated by the following examples.
MIX DESIGN DETAILS
1  Grad of Concrete  :  M30 
2  Cement  :  Three mixes are to be designed 
MIXAWith PPC (Flyash based) conforming to IS:1489partI1991. 7 days strength 38.5 N/mm^{2}. Specific Gravity : 3.00  
MIXBWith OPC43 Grade conforming to IS: 81121989. 7 days strength 40.7 n/mm^{2}. Specific Gravity : 3.15  
MIXCWith OPC of MixB and Fly ash conforming to IS:3812 (PartI)2003 Specific Gravity : 2.25  
Note: Requirements of all the three mixes are the same. Fine Aggregate, Coarse Aggregate and normal Super plasticizer are the same for all the three mixes.  
3  Fly ash replacement  :  30% Fly ash is required to be replaced with the total cementitious materials. 
4  Maximum nominal size of aggregates  :  20 mm Crushed aggregate 
5  Fine aggregate  :  River sand of ZoneII as per IS:3831970 
6  Minimum cement content  :  320 kg/m^{3} including Fly ash 
7  Maximum free W/C Ratio  :  0.45 
8  Workability  :  50 mm slump 
9  Exposure condition  :  Severe for RCC work 
10  Method of placing  :  Site mixing 
11  Degree of supervision  :  Good 
12  Maximum of cement content (Fly ash not included)  :  450 kg/m^{3} 
13  Chemical admixture  :  Super plasticizer conforming to IS:91031999. With the given requirements and materials, the manufacturer of Normal Super plasticizer recommends dosages of 17 gm per kg of OPC, which will reduce 24% of water without loss of workability. For fly ash included cement dosages will be required to be adjusted by experience/ trials. 
TEST DATA FOR MATERIALS
1. The grading of fine aggregate, 10 & 20 mm aggregates are as given in Table. 1. Fine aggregate is of zoneII as per IS:3831970. 10 and 20 mm crushed aggregate grading are single sized as per IS: 3831970.
2. Properties of aggregates
Tests 
Fine aggregate 
10 mm aggregate 
40 mm aggregate 
Specific Gravity 
2.65 
2.65 
2.65 
Water Absorption% 
0.8 
0.5 
0.5 
3. Target strength for all A, B and C mixes
f_{ck} = f_{ck}+ 1.65 x S
30 + 1.65 x 5
= 38.3 N/mm^{2} at 28 days age
4. For Mix A and B free W/C ratio with crushed aggregate and required target strength of 38.3 N/mm^{2} at 28 days from Fig. 1 Curve D found to be 0.45. Taking into the consideration of water in admixture, let it be 0.44. This is lower than specified maximum W/C ratio value of 0.45.
Note:In absence of cement strength, but cement conforming to IS Codes, assume from Fig. 1 and Fig. 2.
Curve A and B for OPC 33 Grade
Curve C and D for OPC 43 Grade
Curve E and F for OPC 53 Grade
Take curves C and D for PPC, as PPC is being manufactured in minimum of 43 Grade of strength.
5. Other data’s: The Mixes are to be designed on the basis of saturated and surface dry aggregates. At the time of concreting, moisture content of site aggregates are to be determine. If it carries surface moisture this is to be deducted from the mixing water and if it is dry add in mixing water the quantity of water required for absorption. The weight of aggregates are also adjusted accordingly.
DESIGN OF MIXA WITH PPC
a) Free W/C ratio for the target strength of 38.3 N/mm2 as worked out is 0.44.
b) Free water for 50 mm slump from Table 2 for 20 mm maximum size of aggregate.
2/3*180+1/3*210= 190 kg/mm^{3}
From trials it is found that Normal Super plasticizer at a dosages of 20gm/kg of cement may reduce 24% water without loss of workabilityThen water = 190 – (190 x 0.24) = 144.4 kg/m^{3}
for trials say 145 kg/m^{3}
c) PPC = 145/0.44 = 329.5 kg/m^{3}
Say 330 kg/m^{3}. This is higher than minimum requirement of 320 kg/m^{3}
d) Formula for calculation of fresh concrete weight in kg/m^{3}
U_{M} = 10 x G_{a}(100 – A) + C_{M} (1 – G_{a} /G_{c} ) – W_{M} (G_{a} – 1)
Where,
U_{M} = Wight of fresh concrete kg/m^{3}
G_{a} = Weighted average specific gravity of combined fine and coarse aggregate bulk, SSD
G_{c} = Specific gravity of cement. Determine actual value, in absence assume 3.15 for OPC and 3.00 for PPC (Fly ash based)
A = Air content, percent. Assume entrapped air 1% for 40 mm maximum size of aggregate, 1.5% for 20 mm maximum size of aggregate and 2.5% for 10mm maximum size of aggregate. There are always entrapped air in concrete. Therefore ignoring entrapped air value as NIL will lead the calculation of
higher value of density.
W_{M} = Mixing water required in kg/m^{3}
C_{M} = Cement required, kg/m^{3}
Note: The exact density may be obtained by filling and fully compacting constant volume suitable metal container from the trial batches of calculated design mixes. The mix be altered with the actual obtained density of the mix.
U_{M} = 10 x G_{a} (100 – A) + C_{M} (1 – G_{a} /G_{c} ) – W_{M} (G_{a} – 1)
= 10 x 2.65 (100 – 1.5) + 330(1 2.65/3.00) – 145 (2.65 1)
2409.6 kg/m^{3}
Say 2410 kg/m^{3}
e) aggregates = 2410 – 330 – 145 = 1935 kg/m^{3}
f) Fine aggregate = From Table 3 for zoneII Fine aggregate and 20 mm maximum size of aggregate, W/C ratio = 0.44, 50 mm slump found to be 34%.
Fine aggregate = 1935 x 0.34 = 658 kg/m^{3}
Coarse aggregate = 1935 – 658 = 1277 kg/m^{3}
10 and 20 mm aggregate are single sized as per IS: 3831970. Let they be combined in the ratio of 1.2:1.8 to get 20 mm graded aggregate as per IS: 3831970
10 mm aggregate = 510 kg/m^{3}
20 mm aggregate = 767 kg/m^{3}
g) Thus for M30 Grade of concrete quantity of materials per cu.m. of concrete on the basis of saturated and surface dry aggregates:
Water = 145 kg/m^{3}
PPC = 330 kg/m^{3}
Fine Aggregate (sand) = 658 kg/m^{3}
10 mm Aggregate = 510 kg/m^{3}
20 mm Aggregate = 767 kg/m^{3}
Normal Super Plasticizer = 6.6 kg/m^{3}
MIX B WITH OPC
a) Water = 190 – (190 x 0.24) = 144.4 kg/m^{3}say 145 kg/m^{3}
b) OPC = 145/0.44 = say 330 kg/m^{3}
c) Density:
10 x 2.65 (100 – 1.5) + 330 (1 – 2.65/3.15) – 145 (2.65 – 1)
= 2423.5 kg/m^{3}say 2425 kg/m^{3}
d) Total Aggregates = 2425 – 145 – 330 = 1950 kg/m^{3}
Fine Aggregate = 1950 x 0.34 = say 663 kg/m^{3}
Coarse aggregate = 1950 – 663 = 1287 kg/m^{3}
10 mm Aggregate = 1287×1.2/3 = 515 kg/m^{3}
20 mm Aggregate = 1287×1.8/3 = 772 kg/m^{3}
e) Thus for M30 Grade of concrete quantity of materials per cu.m of concrete on the basis of SSD aggregates are given below:
Water = 145 kg/m^{3}
OPC = 330 kg/m^{3}
Fine Aggregate (sand) = 663 kg/m^{3}
10 mm Aggregate = 515 kg/m^{3}
20 mm Aggregate = 772 kg/m^{3}
Normal Super Plasticizer = 5.610 kg/m^{3}
MIX. C WITH OPC + FLYASH
With the given set of materials increase in cementitious materials = 12%
Total cementitious materials = 330 x 1.12 = 370 kg/m^{3}
Materials 
Weight (kg/m^{3}) 
Volume (m^{3}) 
OPC = 370 x 0.70 
259/3150 
0.0822 
Flyash = 370x 0.30 
111/2250 
0.0493 
Free Water = 145 x 0.95 
138/1000 
0.138 
Normal Super Plasticizer = 7.5kg 
7.5/1150 
0.0065 
Air = 1.5% 
0.015` 

Total 
0.291 

Total Aggregates = 1 – 0.291 
0.709 

1.00 

Coarse Aggregate 
1287/2650 
0.4857 
Fine Aggregate = 0.709 – 0.4857 = 0.2233
= 0.2233 x 2650 = 592 kg
Note:
1. Specific gravity of Normal Superplasticizer = 1.15
2. Addition of Flyash reduces 5% of water demand.
M30 Grade of concrete quantity of material per cu.m of concrete on the basis of saturated and surface dry aggregates of Mix ‘A’, ‘B’ and ‘c’ are given below:
Materials 
MIX. ‘A’ with PPC 
Mix. ‘B’ with OPC 
Mix. ‘C’ with OPC+Flyash 
Water kg/m^{3} 
145 
145 
138 
PPC kg/m^{3} 
330 
– 
– 
OPC kg/m^{3} 
– 
330 
259 
Flyash kg/m^{3} 
– 
– 
111 
Fine Agg. kg/m^{3} 
658 
663 
592 
10mm Agg. kg/m^{3} 
510 
515 
515 
20 mm Agg. kg/m^{3} 
767 
772 
772 
Normal Super plasticizer kg/m^{3} 
6.6 
5.61 
7.5 
W/Cementations ratio 
0.44 
0.44 
0.373 
Note:
1. For exact W/C ratio the water in admixture should also be taken into account.
2. The W/C ratio of PPC and OPC is taken the same assuming that the strength properties of both are the same. If it is found that the PPC is giving the low strength then W/C ratio of PPC have to be reduce, which will increase the cement content. For getting early strength and in cold climate the W/C ratio of PPC shall also be required to be reduced.
3. PPC reduces 5% water demand. If this is found by trial then take reduce water for calculation.
4. If the trial mixes does not gives the required properties of the mix, it is then required to be altered accordingly. However, when the experiences grows with the particular set of materials and site conditions very few trials will be required, and a expert of such site very rarely will be required a 2nd trial.
CONCLUSION
1. For M30 Grade concrete having same material and requirement,
but without water reducer, the PPC and OPC required will be 190/0.45 = 422kg/m^{3}
2. With the use of superplasticizer the saving in cement is 92 kg/^{3}and water 45 lit/^{3}for PPC and OPC.
3. In the Fly ash concrete the saving in cement is 163 kg/m3 and water 52 lit/^{3}including utilization of 111 kg/^{3}of fly ash witch is a waste material.
4. If 50 million tonnes cement in making concrete uses Water Reducers 7500000 tonnes of cement can be saved. 3750000 KL of potable water will be saved and the saving of Rs. 3300 crores per year to the construction Industry. 6975000 tonnes of CO2 will be prevented to be emitted to the atmosphere. The benefits in the uses of water reducers not limited to this. When water reduces shrinkage and porosity of concrete are reduces which provides the durability to concrete structures.
6. India is facing serious air, water, soil, food and noise pollution problems. Every efforts therefore are necessary to prevent pollution on top priority basis.
REFERENCES:
1  IS : 3831970  Specifications for coarse and fine aggregates from natural sources for concrete (second revision) BIS, New Delhi  
2  IS: 4562000  Code of practice for plain and reinforced concrete (fourth revision), BIS, New Delhi  
3  IS: 91031999  Specification for admixtures for concrete (first revision) BIS, New Delhi  
4  IS: 81121989  Specifications for 43 Grade ordinary portland cement (first revision) BIS, New Delhi  
5  IS: 2386 (PartIII) 1963  method of test for aggregate for concrete. Specific gravity, density, voids, absorption and bulking, BIS, New Delhi  
6  IS: 3812 (PartI) 2003  Specification for pulverized fuel ash: PartI for use as pozzolana in cement, cement mortar and concrete (second revision) BIS, New Delhi  
7  IS: 1489PartI 1991  Specifications for portland pozzolana cement (PartI) Flyash based. (Third revision), BIS, New Delhi  
8  Kishore Kaushal, “Design of Concrete Mixes with HighStrength Ordinary Portland Cement”. The Indian Concrete Journal, April, 1978, PP. 103104  
9  Kishore Kaushal, “Concrete Mix Design”. A manual published for Structural Engineering Studies, Civil Engineering Department, University of Roorkee, 1986.  
10  Kishore Kaushal, “Concrete Mix Design Based on Flexural Strength for AirEntrained Concrete”, Proceeding of 13^{th} Conference on our World in Concrete and Structures, 2526, August, 1988, Singapore.  
11  Kishore Kaushal, “Concrete Mix Design”, Indian Concrete Institute Bulletin September, 1988, pp. 2740 and ICI Bulletin December, 1988, pp. 2131.  
12  Kishore Kaushal, “Method of Concrete Mix Design Based on Flexural Strength”, Proceeding of the International Conference on Road and Road Transport Problems ICORT, 1215 December, 1988, New Delhi, pp. 296305.  
13  Kishore Kaushal, “Mix Design Based on Flexural Strength of AirEntrained Concrete”. The Indian Concrete Journal, February, 1989, pp. 9397.  
14  Kishore Kaushal, “Concrete Mix Design”, VIII All India Builders Convention 2931, January, 1989, Hyderabad, organized by Builders Association of India, Proceeding Volume pp. 213260.  
15  Kishore Kaushal, “Concrete Mix Design Containing Chemical Admixtures”, Journal of the National Building Organization, April, 1990, pp. 112.  
16  Kishore Kaushal, “Concrete Mix Design for Road Bridges”, INDIAN HIGHWAYS, Vol. 19, No. 11, November, 1991, pp. 3137  
17  Kishore Kaushal, “A Concrete Design”, Indian Architect and Builder, August, 1991, pp. 5456  
18  Kishore Kaushal, “ Mix Design for Pumped Concrete”, Journal of Central Board of Irrigation and Power, Vol. 49, No.2, April, 1992, pp. 8192  
19  Kishore Kaushal, “Concrete Mix Design with Fly Ash”, Indian Construction, January, 1995, pp. 1617  
20  Kishore Kaushal, “HighStrength Concrete”, Civil Engineering and Construction Review, March, 1995, pp. 5761.  
21  Kishore Kaushal, “HighStrength Concrete”, Bulletin of Indian Concrete Institute No. 51, AprilJune, 1995, pp. 2931  
22  Kishore Kaushal, “Mix Design of PolymerModified Mortars and Concrete”, New Building Materials & Construction, January, 1996, pp. 1923.  
23  Kishore Kaushal, “Concrete Mix Design Simplified”, Indian Concrete Institute Bulletin No. 56, JulySeptember, 1996, pp. 2530. 

24  Kishore Kaushal, “Concrete Mix Design”, A Manual Published by M/S Roffe Construction Chemicals Pvt. Ltd., Mumbai, pp. 136  
25  Kishore Kaushal, “Concrete Mix Design with Fly Ash & Superplasticizer”, ICI Bulletin No. 59, AprilJune 1997, pp. 2930  
26  Kishore Kaushal. “Mix Design for Pumped Concrete”, CE & CR October, 2006, pp. 4450. 
Table. 1: Grading of Aggregates
IS Sieve Designation 
Percentage Passing 

Fine Aggregate 
Crushed Aggregate 

10 mm 
20 mm 

40 mm 
– 
– 
100 
20 mm 
– 
– 
100 
12.5 mm 
– 
100 
– 
10 mm 
100 
85 
4 
4.75 mm 
99 
5 
0 
2.36 mm 
88 
0 

1.18 mm 
74 

600 Micron 
43 

300 Micron 
24 

150 Micron 
6 
Table. 2: Approximate freewater content (kg/m3) required to give various levels of workability for nonairentrained (with normal entrapped air) concrete.
Maximum size of aggregate (mm)  Type of aggregate  Slump (mm) Degree of workability 
— vary low 
2575 … Low 
50100 … Medium 
100180 … High 
10 
Uncrushed Crushed 
150 180 
205 235 
220 250 
240 265 

20 
Uncrushed Crushed 
140 170 
180 210 
195 225 
210 245 

40 
Uncrushed Crushed 
120 155 
160 190 
175 205 
190 220 
Note: When coarse and fine aggregate of different types are used, the free water content is estimated by the expression.
Where, W_{f} = Free water content appropriate to type of fine
Aggregate And W_{c} = Free water content appropriate to type of coarse aggregate.
Table. 3: Proportion of fine aggregate (percent) with 10mm and 20mm maximum sizes of aggregates and with different workability
GradingZone of F.A 
W/C Ratio 
10 mm aggregate Workability 
20 mm aggregate Workability 

VL 
L 
M 
H 
VL 
L 
M 
H 

I 
0.3 
4353 
4656 
4960 
5467 
3239 
3542 
3947 
4453 
0.4 
4656 
4858 
5162 
5769 
3442 
3745 
4149 
4656 

0.5 
4858 
5061 
5365 
5972 
3745 
3947 
4352 
4859 

0.6 
5061 
5263 
5668 
6275 
3947 
4150 
4554 
5061 

0.7 
5264 
5566 
5870 
6477 
4150 
4453 
4757 
5364 

II 
0.3 
3643 
3746 
4049 
4454 
2732 
2835 
3239 
3544 
0.4 
3746 
3948 
4251 
4657 
2834 
3037 
3341 
3746 

0.5 
3948 
4150 
4453 
4759 
3037 
3239 
3543 
3948 

0.6 
4150 
4252 
4556 
4962 
3239 
3441 
3645 
4150 

0.7 
4252 
4455 
4758 
5164 
3441 
3644 
3847 
4353 

III 
0.3 
2936 
3237 
3340 
3744 
2327 
2428 
2732 
3035 
0.4 
3137 
3339 
3542 
3846 
2428 
2630 
2833 
3137 

0.5 
3239 
3441 
3644 
4047 
2530 
2732 
2935 
3339 

0.6 
3441 
3642 
3845 
4249 
2732 
2934 
3136 
3541 

0.7 
3542 
3744 
3947 
4351 
2834 
3036 
3238 
3643 

IV 
0.3 
2629 
2732 
2933 
3237 
1923 
2124 
2327 
2630 
0.4 
2731 
2933 
3035 
3438 
2124 
2226 
2428 
2831 

0.5 
2832 
3034 
3236 
3540 
2225 
2427 
2629 
2933 

0.6 
3034 
3136 
3338 
3642 
2327 
2529 
2731 
3035 

0.7 
3135 
3237 
3539 
3743 
2528 
2630 
2832 
3236 
Table. 4: Proportion of fine aggregate (percent) with 40 mm maximum sizes of Aggregates and with different workability.
Grading Zone of F.A 
W/C Ratio 
40 mm aggregate Workability 

VL 
L 
M 
H 

I 
0.3 
2733 
2935 
3339 
3846 
0.4 
2935 
3138 
3542 
4149 

0.5 
3138 
3341 
3744 
4352 

0.6 
3341 
3643 
3947 
4554 

0.7 
3644 
3846 
4250 
4757 

II 
0.3 
2227 
2329 
2733 
3128 
0.4 
2429 
2531 
2835 
3241 

0.5 
2531 
2733 
3037 
3443 

0.6 
2733 
2936 
3239 
3645 

0.7 
2936 
3138 
3442 
3847 

III 
0.3 
1822 
2023 
2227 
2631 
0.4 
2024 
2125 
2428 
2732 

0.5 
2125 
2327 
2530 
2934 

0.6 
2327 
2429 
2732 
3036 

0.7 
2429 
2631 
2934 
3236 

IV 
0.3 
1618 
1820 
1922 
2226 
0.4 
1720 
1921 
2024 
2427 

0.5 
1821 
2023 
2225 
2529 

0.6 
2023 
2224 
2327 
2630 

0.7 
2124 
2326 
2529 
2832 
V_{L} = Very low workability.
L = Low workability – slump 2575 mm
M = medium workability – slump 50100 mm
H = High workability slump 100180 mm