Project on Concrete Mix Design for various grades of Concrete
Calculate the Concrete Mix Design for M35 grade concrete with fly ash
the mix design calculation of M35 Grade Concrete with Fly ash admixture and Poly Carboxylite type super plasticiser, as per Indian Standard Codebook IS10262(2009)
Guidelines for Concrete Mix Proportioning :
Mix Design calculation procedure is the same when either GGBS or Fly ash is used, the only change will be the specific gravity of the admixture.
The specific gravity of fly ash ranges from 2.1 to 3 whereas the specific gravity of GGBS is 2.85.
I. STIPULATIONS FOR PROPORTIONING OF M35 GRADE CONCRETE
This section has Specifications of the materials and requirements of the concrete to be made.
| A | Grade Designation | M35 | |
| B | Type of Cement | OPC 53 | |
| C | Type of Admixture | Fly ash | |
| D | Maximum Nominal Size of Aggregate |
20mm | |
| E | Minimum Cement Content | 340kg | Table 5-IS456 |
| F | Maximum Cement Content | 450kg | As per code |
| G | Partial replacement of cement by Fly ash |
30% | as per requirement |
| H | Maximum W/C ratio | 0.45 | Table 5-IS456 |
| I | Workability | 100mm | |
| J | Chemical Admixture | PCS Type |
II. TEST DATA FOR MATERIALS
Various laboratory tests on materials are required to use in this action. Standard values are assumed below.
| A | Cement Used | OPC 53 | Confirming to IS8112 |
| B | Specific Gravity of Cement | 3.15 | Test – IS: 2720 |
| C | Mineral Admixture | Fly ash | Confirming to IS12089 |
| D | Specific Gravity of Fly ash | 2.90 | |
| E | Chemical Admixture | @0.6% | IS9103 |
| F | Specific Gravity of | Test – IS 2386 | |
| Coarse Aggregate | 2.74 | ||
| Fine Aggregate | 2.74 | ||
| Admixture PCE based | 1.12 | ||
| G | Water Absorption | Test – IS 2386 | |
| Coarse aggregate | 0.5 % | ||
| Fine aggregate | 1 % | ||
| H | Sieve Analysis | Test – IS 2386 | |
| Coarse aggregate | Confirming to Table 2-IS383 |
||
| Fine aggregate | Zone II | Confirming to Table 4-IS383 |
III. TARGET STRENGTH FOR MIX PROPORTIONS OF M35 GRADE CONCRETE
The strength of the concrete may deviate based on the quality of the material, method of mixing and construction practices. Hence target strength (Fck) should be higher than the required strength of the concrete (fck). The value of standard deviation(s) for different grades of concrete is given in Table 1 of IS456.
| Fck | = fck+1.65s | “S” from Table1-IS10262 |
| Fck | = 35+1.65×5 | |
| Fck | = 43.25 N/mm2 |
IV. SELECTION OF WATER-CEMENT RATIO
The maximum water-cement ratio for different grades of concrete is given in Table 5-IS456. You can reduce the water-cement ratio based on your requirements. The Water-cement ratio directly affects the strength of the concrete.
| Maximum W/C ratio | =0.45 | Table 5-IS456 |
| Adopted W/C ratio | =0.45 |
V. SELECTION OF WATER CONTENT
| Maximum Water Content | =186 L | Table 2-IS1026 |
Above water-content is for 25 to 50mm slump, but we need 100mm slump for our concert as per specification. So we need to increase the water-content to get the required slump. Clause 4.2 of IS1026 suggests to increases 3% of water-content to get an extra 25mm slump. Hence we to increase water content by 6% to get an additional 50mm slump for our concrete.
| Water-content for 100mm Slump | =186+(0.06*186) |
| =197.16 L |
Since we are using superplasticizers water-content can be reduced inorder to get strength in concrete. The amount of water-content to be reduced depends on the type of superplasticizer.
| Percentage of Reduction in water content | =20% |
| Water content requirement after SP | =198 – (0.20*198) |
| =157.73 | |
| Adopted Water Content | =160 L |
VI. CALCULATION OF CEMENT AND FLY ASH CONTENT
| Adopted Water Cement Ratio | =0.45 |
| Total Cementitious (Cement +Fly ash) requirement | = Water Content / WaterCement ratio |
| =160/0.45 | |
| =355.55 kg |
Since Fly ash is used the amount of Cementitious content (Cement+Fly ash) shall be increased to get good workability and strength. The percentage of cementitious content to be increased depends on the experience and research. Here we have increased the cementitious content by 10%.
| Final Cementitious Content (Cement+Fly ash) |
= 356*1.10 | |
| =391.6 kg | ||
| Minimum Cement Content required for ‘severe’ exposure |
=340kg | Table 5-IS456 |
| Adopted Cementious content | =391.6 kg | > 340kg |
| Fly ash content requirement | = 391.6 * 0.30 | 30% replacement |
| = 117.48 ~ 118 kg | ||
| Cement Content requirement | =Cementious content – Fly ash | |
| =391.6-117.48 | ||
| = 274.12 |
Calculation of Super Plasticiers @ 0.6 percent to the mass of cementitious content = = 391.6*(0.6/100) = 2.35 kg
VII COARSE AND FINE AGGREGATE
| Coarse Aggregate ratio | = 0.62 | Table3-IS10262 (For W/C =0.5) |
| Coarse Aggregate ratio for 0.45 w/c ratio |
= 0.63 | (adding 0.01 for every decrease .05 and vice versa) |
| Final Fine Aggregate ratio | = 0.37 | (1-0.63) = 0.37 |
VIII MIX CALCULATIONS OF M35 GRADE CONCRETE
| A | Volume of Concrete | = 1 cu.m |
| B | Total Volume of Cement | = Cement/(S.G*1000) |
| = 275/(3.15*1000) | ||
| = 0.087 cu.m | ||
| C | Total Volume of Fly ash | = Flyash/(S.G*1000) |
| = 118/(2.5*1000) | ||
| = 0.041 cu.m | ||
| D | Volume of Water | =Water /(S.G*1000) |
| = 160/(1*1000) | ||
| = 0.160 cu.m | ||
| E | Volume of Superplasticizers | = Superplasticizers /(S.G*1000) |
| = 2.35/(1.12*1000) | ||
| = 0.002 cu.m | ||
| F | Total Aggregates requirement | = A – (B+C+D+E) |
| =1 -(0.087 +0.041+0.160+0.002) | ||
| =0.71 cu.m | ||
| G | Coarse Aggregate (C.A) | = F * C.A ratio * S.G * 1000 |
| = 0.71*0.63 *2.74 *1000 | ||
| = 1225.6 kg | ||
| I | Fine Aggregate (F.A) | = F * F.A ratio * S.G * 1000 |
| = 0.71*0.37*2.74 *1000 | ||
| =719.8 kg |
Cement Flyash Sand Aggregate Water and Superplasticizer needed for M35 grade concrete
| S.No. | MATERIALS | QUANTITY |
| 1 | Cement | 275 kg |
| 2 | Flyash | 118 kg |
| 3 | Fine Aggregate | 720 kg |
| 4 | Coarse Aggregate (20mm) | 1226 kg |
| 5 | WATER | 160 L |
| 6 | PCE based SuperPlasticizer | 2 L |
To find the design mix ratio divide the calculated value of all materials by the weight of cement. Therefore Mix Ratio of M35 Grade concrete by weight is Cement : Flyash: F.A : C.A : Water = 1:0.4:2.6:4.46:0.58
Calculate the Concrete Mix Design for M50 grade concrete without Fly ash :
Stipulations for Concrete Mix Design
- Grade designation : M 50
- Type of cement : OPC 53 grade confirming to IS 8112
- Maximum nominal size of aggregate : 20 mm
- Minimum cement content : 360 kg/m3
- Maximum water-cement ratio : 0.35
- Workability : 50-75 mm (slump)
- Exposure condition : Extreme (for reinforced concrete)
- Method of concrete placing : Pumping
- Degree of supervision : Good
- Type of aggregate : Crushed angular aggregate
- Maximum cement content : 450 kg/m3
- Chemical admixture type : Super Plasticizer
Test Data for Materials
The following data are collected by performing standard tests in a laboratory.
Specific gravity of cement : 3.12
Specific gravity of Coarse Aggregate : 2.74
Specific gravity of Fine Aggregate : 2.56
Procedure for Concrete Mix Design of M 50 Concrete
1. Target Strength for Mix Proportioning
ftarget = fck + 1.65 x s
ftarget denotes the Target Average Compressive Strength at 28 days,
fck denotes the Characteristic Compressive Strength at 28 days,
‘s’ stands for Standard Deviation
According to the table 1 of IS: 10262-2009 ,
standard deviation, s = 5.0 N/mm2
Therefore, target strength = 50 + 1.65 x 5.0 = 58.25 N/mm2
2. Selection of Water/Cement Ratio
From Table 5 of IS 456 : 2000,
Maximum water-cement ratio = 0.35
3. Selection of Water Content
From Table 2 of IS 456, maximum water content =186 litres (for 25 to 50 mm slump range) for 20 mm aggregate.
Estimated water content for 100 mm slump =186+(6/100) x 186 =197 litres.
(Note: If Super plasticizer is used, the water content can be reduced up to 20% and above.)
Based on trials with Super plasticizer water content reduction of 27% has been achieved, Hence the arrived water content = 197 – [197 x (27/100)] = 143 litres.
4. Calculation of Cement Content
Water-cement ratio = 0.35
Cement content = 143/0.35 = 410 kg/m3
From Table 5 of IS 456, minimum cement content for ‘Extreme exposure’ condition = 360 kg/m3
410 kg/m3 > 360 kg/m3, hence, O.K.
5. Proportion of Volume of Coarse Aggregate and Fine Aggregate Content
From Table 3 of IS 10262. volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for a water-cement ratio of 0.50 =0.62.
In the present case, the water-cement ratio is 0.35. Therefore. the volume of coarse aggregate is required to be increased to decrease the fine aggregate content.
As the water-cement ratio is lower by 0.10. the proportion of the volume of coarse aggregate is increased by 0.02 (at the rate of -/+ 0.01 for every ± 0.05 change in the water-cement ratio).
Therefore. the corrected proportion of the volume of coarse aggregate for the water-cement ratio of 0.35 = 0.65.
NOTE – In case the coarse aggregate is not angular one, then the volume of coarse aggregate may be increased by 10 percent based on experience.
For pumpable concrete, these values should be reduced by 10 percent.
Therefore, volume of coarse aggregate = 0.65 x 0.9 = 0.585.
Volume of fine aggregate content =1 – 0.585 =0.415
6. Mix Calculations
a) Volume of concrete = 1m3
b) Volume of cement = (Mass of Cement/ Its Specific Gravity ) X (1/1000)
= (410/3.12) X (1/1000)
= 0.131 m3
c) Volume of Water = (Mass of water/specific gravity of water) X (1/1000)
= (143/1) X (1/1000)
= 0.143 m3
d) Volume of Superplasticizer = (Mass of Superplasticizer / Specific gravity of admixture) X (1/1000)
= (8.2/1.145) X (1/1000)
= 0.007 m3
e) Volume of all aggregate = (a – (b + c + d))
= 1 – (0.131 + 0.143+0.007)
= 0.719 m3
e) Mass of coarse aggregate = Volume of All Aggregate X Volume of Coarse Aggregate X Specific Gravity of Coarse Aggregate X 1000
= 0.719 x 0.585 x 2.74 x 1000
= 1152.48 kg
f) Mass of fine aggregate = Volume of all aggregate X volume of fine aggregate X Specific gravity of fine aggregate X 1000
= 0.719 x 0.415 x 2.56 x 1000
= 763.86 kg
7. Concrete Mix Proportions
- Cement = 410 kg/m3
- Water = 143 kg/m3
- Super plasticizer = 7 kg/m3
- Fine aggregates = 763.86 kg/m3
- Coarse aggregate = 1152.48 kg/m3
- W/c = 0.35