Project on Concrete Mix Design for various grades of Concrete
MIX DESIGN FOR M35 GRADE CONCRETE WITH FLYASH AND M50 GRADE
CONCRETE WITHOUT FLYASH
AIM:- To calculate the Concrete Mix Design for M35 grade concrete with flyash and M50 grade concrete without flyash
INTRODUCTION:- Concrete is a complex material and has the right mix of constituents of concrete, which if not done properly and will have adverse effect on properties of concrete. Concrete mix design is a systematic process of choosing economical relative proportion of various ingredients from available material that gives the concrete of desired workabilty. The design is done according to the requirements of concrete strength. So we can achieve the desirable properties either it is in fresh state or in the hardened stage. The project is consisting of two parts, the first part depicts the design of M35 grade cement with flyash and second part is about the design of M50 grade concrete without flyash
OBJECTIVES:- To achieve the desired workability in the plastic stage, To achieve the desired minimum strength in the hardened stage, To achieve the desired durability in the specified environmental condition, To produce concrete as economically as possible.
There are guideline (Bureau of IS-IS 10262-2019, Bureau of IS-IS 10262-2009) and recommended guideline for concrete mix design - IS 10262-1982.
EQUATIONS REQUIRED FOR THE MIX DESIGN OF CONCRETE:-
- Target mean strength of concrete
- ft=fck + 1.65S
- ft= taget average compressive strength of concrete at 28 days
- fck= characteristics compressive strength
- S= standard deviation
- ft=fck + 1.65S
- Cement Content
- cement content= water content/ water-cement ratio
- Volume calculations
- volume of concrete
- volume of cement= (mass of cement/specific gravity of cement)x( 1/1000)
- volume of water=(mass of water/specific gravity of water)x( 1/1000)
- volume of chemical admixture=(mass of chemical admixture/specific gravity of admixture )x( 1/1000)
- volume of aggregates(Fine aggregates and Coarse aggregates) = a-(b+c+d)
- mass of coarse aggregate=ex volume of coarse aggregatex specific gravity of coarse aggregatex1000
- mass of fine aggregate=ex volume of fine aggregatex specific gravity of fine aggregatex1000
PART A:-Mix design for M35 grade concrete with flyash
STEP 1- Stipulations for Concrete mix design
| Grade designation | M35 |
| Type of cement | OPC 43 grade confirming to IS 8112 |
| Type of mineral admixture | Flyash confirming to IS 3812 (Part 1) |
| Maximum nominal size of aggregate | 20mm |
| Minimum cement content | 320kg/m3( Table 5 of IS 456-2000 Exposure condition) |
| Maximum water-cement ratio | 0.45( Table 5 of IS 456-2000 Exposure condition) |
| Workability | 100mm(slump value for pumpable concrete) |
| Exposure condition | Severe( for reinforced concrete) |
| Method of concrete placing | Pumping |
| Degree of supervision | Good |
| Type of aggregate | Crushed angular aggregate |
| Maximum cement content | 450kg/m3 |
| Chemical admixture type | Super plasticizer |
STEP 2- Test data for materials
| Cement used | OPC 43 grade confirming to IS 8112 |
| Specific gravity of cement | 3.15 |
| Flyash | Confirming to IS 3812(Part 1) |
| Specific gravity of flyash | 2.2 |
| Chemical admixture | Superplasticizers confirming to IS 9103 |
| Specific gravity of coarse aggregate | 2.74 |
| Specific gravity of fine aggregate | 2.74 |
| Water absorption of coarse aggregate | 0.5% |
| Water absorption of fine aggregate | 1.0% |
| Free surface moisture of coarse aggregate | Nil |
| Free surface moisture of fine aggregate | Nil |
| Sieve analysis coarse aggregate | Confirming to table 2 of IS 383 |
| Sieve analysis fine aggregate | Confirming to Grading zone I of table 4 of IS 383 |
STEP 3- TARGET STRENGTH OF MIX PROPORTIONING
ft=fck + 1.65S
- ft= taget average compressive strength of concrete at 28 days
- fck= characteristics compressive strength=35N/mm2
- S= standard deviation(from table 1 of IS 10262:2009/table 2 of IS 10262:2019 S=5N/mm2)
ft=35+(1.65x5)
=43.25N/mm2
TARGET MEAN STRENGTH= 43.25N/mm2
STEP 4- SELECTION OF WATER-CEMENT RATIO
The maximum water-cement ratio for severe exposure is 0.45(From table 5 of IS456:2000)
From figure 1 of IS10262:2019, Graph shows the water cement ratio as 0.39
0.39<0.45
ADOPTED WATER-CEMENT RATIO=0.39
STEP 5-SELECTION OF WATER CONTENT
From table 2 of IS 10262-2009, maximum water content for 20mm aggregates is 186 litres(for 25 to 50mm slump range).
Estimated water content for 100mm slump=186+(6/100 x 186)
=197 litres
As superplasticizers are used, the water content can be reduced to 30%. Based on trials water content reduction of 29% is achieved with plasticizers
Hence arrived water content= 197-(197x0.29)= 140 litres.
WATER REQUIRED=140 LITRES
STEP 6- CALCULATION OF CEMENT AND FLYASH
Adopted water-cement ratio= 0.39
total cementitious material required( cement+flyash)= water content/ water-cement ratio
=140/0.39
= 359 kg/m3
From table 5 of IS456:2000 minimum cement content for severe exposure condition= 320kg/m3
359kg/m3>320kg/m3, hence okay.
Now to proportion a mix containing flyash the following steps are suggested
The percentage of flyash needs to be decided based on project requirement and quality of materials
In some case increase in cementitious material can be warranted. Increase in cementitious material content and its percentage may be based on experience and trial. Here we are increasing cementitious content by 10%.
Then cementitious material content= 359x1.1= 395kg/m3
water content=140kg/m3
so, water-cement ratio= 140/395=0.35
Flyash content is taken as 30% of the total cementitious material= 395x(30/100)
=118kg/m3
Cement required= 395-118=277kg/m3
Saving of cement while using flyash= 359-277=82kg/m3
CEMENTITIOUS MATERIAL, CEMENT AND FLYASH REQUIRED IS 395kg/m3, 277kg/m3 and 118kg/m3 and the revised water-cement ratio is 0.35 respectively.
STEP 7- VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From table 3 of IS 10262:2009, volume of coarse aggregate corresponds to 20mm size aggregate and fine aggregate for water cement ratio 0.5 is 0.60
In present case the water-cement ratio is 0.35. Therefore the volume of coarse aggregate needs to be increased to decrease fine aggregate content
As water-cement ratio is lowered by 0.1 the proportion of volume of coarse aggregate is increased by 0.02( at the rate of+/-0.01 for every 0.05 change in water-cement ratio.
therefore the corrected volume of coarse aggregate for water cement ratio of 0.40 is 0.63.
NOTE- If coarse aggregate is not of angular type, then also volume of coarse aggregate may be required to increase based on experience.
For pumpable concrete these values reduced by 10%
therefore volume of coarse aggregate= 0.63x0.9=0.567
volume of fine aggreagtes =1-0.567=0.433
VOLUME OF COARSE AND FINE AGGREGATES ARE 0.567& 0.433 RESPECTIVELY
STEP 8- MIX CALCULATIONS
The mix calculations as per unit volume of concrete
a)volume of concrete=1m3
b)volume of cement= (mass of cement/specific gravity of cement)x( 1/1000)
= (277/3.15)x( 1/1000)=0.088m3
c)volume of flyash=(mass of flyash/specific gravity of flyash)x( 1/1000)
=(118/2.2)x( 1/1000)=0.054m3
d)volume of water=(mass of water/specific gravity of water)x( 1/1000)
= (140/1)x( 1/1000)=0.140m3
e)volume of chemical admixture=(mass of chemical admixture/specific gravity of admixture )x( 1/1000)
=(7.9/1.145)x( 1/1000)=0.007m3
f)volume of aggregates(Fine aggregates and Coarse aggregates) = a-(b+c+d+e)
=1-(0.088+0.054+0.140+0.007)
=0.711m3
mass of coarse aggregate=fx volume of coarse aggregatex specific gravity of coarse aggregatex1000
=0.711x0.567x2.74x1000=1105kg/m3
mass of fine aggregate=fx volume of fine aggregatex specific gravity of fine aggregatex1000
=0.711x 0.433x2.74x1000=844kg/m3
STEP 9- MIX PROPORTIONS
Mass of
- cement=277kg/m3
- flyash=118kg/m3
- water= 140kg/m3
- fine aggregate= 844kg/m3
- coarse aggregate=1105kg/m3
- chemical admixture=7.9kg/m3
- water-cement ratio=0.35
MIX PROPORTION BY WEIGHT 1:3.05:3.99
STEP 10- The slump can be measured, the water content and dosage of admixture shall be adjusted for achieving the required slump on trial. The mix proportion shall be reworked for actual water content and checked for the durability requirement
STEP 11-Two more trials having variations of 10% of water-cement ratio shall be carried out and a graph between three water cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target for field trials.
PART B:-Mix design for M50 grade concrete without flyash
STEP 1- Stipulations for Concrete mix design
| Grade designation | M50 |
| Type of cement | OPC 53 grade confirming to IS 8112 |
| Maximum nominal size of aggregate | 20mm |
| Minimum cement content | 320kg/m3( Table 5 of IS 456-2000 Exposure condition) |
| Maximum water-cement ratio | 0.45( Table 5 of IS 456-2000 Exposure condition) |
| Workability | 100mm(slump value for pumpable concrete) |
| Exposure condition | Severe( for reinforced concrete) |
| Method of concrete placing | Pumping |
| Degree of supervision | Good |
| Type of aggregate | Crushed angular aggregate |
| Maximum cement content | 450kg/m3 |
| Chemical admixture type | Super plasticizer |
STEP 2- Test data for materials
| Cement used | OPC 53 grade confirming to IS 8112 |
| Specific gravity of cement | 3.15 |
| Chemical admixture | Superplasticizers confirming to IS 9103 |
| Specific gravity of coarse aggregate | 2.74 |
| Specific gravity of fine aggregate | 2.74 |
| Water absorption of coarse aggregate | 0.5% |
| Water absorption of fine aggregate | 1.0% |
| Free surface moisture of coarse aggregate | Nil |
| Free surface moisture of fine aggregate | Nil |
| Sieve analysis coarse aggregate | Confirming to table 2 of IS 383 |
| Sieve analysis fine aggregate | Confirming to Grading zone I of table 4 of IS 383 |
STEP 3- TARGET STRENGTH OF MIX PROPORTIONING
ft=fck + 1.65S
- ft= taget average compressive strength of concrete at 28 days
- fck= characteristics compressive strength=50N/mm2
- S= standard deviation(from table 1 of IS 10262:2009, S=5N/mm2)
ft=50+(1.65x5)
=58.25N/mm2
TARGET MEAN STRENGTH= 58.25N/mm2
STEP 4- SELECTION OF WATER-CEMENT RATIO
The maximum water-cement ratio for severe exposure is 0.45(From table 5 of IS456:2000)
From figure 1 of IS10262:2019, Graph shows the water cement ratio as 0.34
0.34<0.45
ADOPTED WATER-CEMENT RATIO=0.34
STEP 5-SELECTION OF WATER CONTENT
From table 2 of IS 10262-2009, maximum water content for 20mm aggregates is 186 litres(for 25 to 50mm slump range).
Estimated water content for 100mm slump=186+(6/100 x 186)
=197 litres
As superplasticizers are used, the water content can be reduced to 30%. Based on trials water content reduction of 29% is achieved with plasticizers
Hence arrived water content= 197-(197x0.29)= 140 litres.
WATER REQUIRED=140 LITRES
STEP 6- CALCULATION OF CEMENT
Adopted water-cement ratio= 0.34
total cementitious material required( cement+flyash)= water content/ water-cement ratio
=140/0.34
= 412 kg/m3
From table 5 of IS456:2000 minimum cement content for severe exposure condition= 320kg/m3
412kg/m3>320kg/m3, hence okay.
CEMENT REQUIRED IS 412kg/m3
STEP 7- VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From table 3 of IS 10262:2009, volume of coarse aggregate corresponds to 20mm size aggregate and fine aggregate for water cement ratio 0.5 is 0.60
In present case the water-cement ratio is 0.34. Therefore the volume of coarse aggregate needs to be increased to decrease fine aggregate content
As water-cement ratio is lowered by 0.1 the proportion of volume of coarse aggregate is increased by 0.02( at the rate of+/-0.01 for every 0.05 change in water-cement ratio.
therefore the corrected volume of coarse aggregate for water cement ratio of 0.40 is 0.632.
NOTE- If coarse aggregate is not of angular type, then also volume of coarse aggregate may be required to increase based on experience.
For pumpable concrete these values reduced by 10%
therefore volume of coarse aggregate= 0.632x0.9=0.569
volume of fine aggreagtes =1-0.569=0.431
VOLUME OF COARSE AND FINE AGGREGATES ARE 0.569& 0.431 RESPECTIVELY
STEP 8- MIX CALCULATIONS
The mix calculations as per unit volume of concrete
a)volume of concrete=1m3
b)volume of cement= (mass of cement/specific gravity of cement)x( 1/1000)
= (412/3.15)x( 1/1000)=0.131m3
c)volume of water=(mass of water/specific gravity of water)x( 1/1000)
= (140/1)x( 1/1000)=0.140m3
d)volume of chemical admixture=(mass of chemical admixture/specific gravity of admixture )x( 1/1000)
=(8.24/1.145)x( 1/1000)=0.007m3
e)volume of aggregates(Fine aggregates and Coarse aggregates) = a-(b+c+d)
=1-(0.131+0.140+0.007)
=0.722m3
mass of coarse aggregate=ex volume of coarse aggregatex specific gravity of coarse aggregatex1000
=0.722x0.569x2.74x1000=1126kg/m3
mass of fine aggregate=fx volume of fine aggregatex specific gravity of fine aggregatex1000
=0.722x 0.431x2.74x1000=853kg/m3
STEP 9- MIX PROPORTIONS
Mass of
- cement=412kg/m3
- water= 140kg/m3
- fine aggregate= 853kg/m3
- coarse aggregate=1126kg/m3
- chemical admixture=8.24kg/m3
- water-cement ratio=0.34
MIX PROPORTION BY WEIGHT 1:2.07:2.73
STEP 10- The slump can be measured, the water content and dosage of admixture shall be adjusted for achieving the required slump on trial. The mix proportion shall be reworked for actual water content and checked for the durability requirement
STEP 11-Two more trials having variations of 10% of water-cement ratio shall be carried out and a graph between three water cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target for field trials.
RESULTS:-
Mix proportion by weight of M35 grade of concrete with flyash is1:3.05:3.99 and its water-cement ratio found to be 0.35.
Mix proportion by weight of M50 grade of concrete without flyash is 1:2.07:2.73 and water-cement ratio found to be 0.34.
CONCLUSION:- Concrete mix designis economically proportioning of concrete ingredients for better strength and durability based on construction site.
APPENDIX:-
a) PHYSICAL CHARACTERISTICS OF DIFFERENT TYPES OF OPC CEMENT
b) Table 5 IS 456:2000, MINIMUM CEMENT CONTENT, MAXIMUM WATER-CEMENT RATIO AND MINIMUM GRADE OF CONCRETE FOR DIFFERENT EXPOSURES WITH NORMAL WEIGHT AGGREGATE OF 20MM NOMINAL SIZE
c) TABLE 2 OF IS 383- GRADE DISTRIBUTION FOR DIFFERENT NOMINAL SIZES OF COARSE AGGREGATES
d) TABLE 4 OF IS383-GRADING OF FINE AGGREGATES
e) TABLE 1 OF IS 10262:2009: ASSUMED STANDARD DEVIATION
f) TABLE 2 OF IS 10262:2009- MAXIMUM WATER CONTENT FOR 20MM AGGREGATE
g) Figure 1(graph) IS 10262-2019, WATER CEMENT RATIO
