Project on Concrete Mix Design for various grades of Concrete
1. Calculate the concrete mix design for M35 grade concrete with fly ash
AIM: To Calculate the Concrete Mix Design for M35 grade concrete with fly ash
INTRODUCTION:
Concrete mix design is the method of finding the precise proportion of cement, sand and aggregates for concrete to achieve the target strength in structures, therefore concrete mix design can be stated as concrete mix in terms of cement: sand: aggregates. The design is done according to the requirements of concrete strength. So, we can achieve the desirable properties of concrete either it is in fresh stage or in hardened stage. The fresh concrete properties like workability, setting time and hardened concrete properties like compressive strength, durability etc. are attained surely by this method. Use of additives like admixtures, retarders etc. other than basic ingredients are used to improve the properties of mix. This project consist of two parts, the first part deals with the design of M35 grade cement with fly ash
OBJECTIVE:
The objective of this project is to produce a mix design for M35 grade concrete containing fly ash. The mix will be prepared as per IS METHOD: Concrete mix proportioning guidelines from IS 10262:2009 and recommented guide lines from IS 10262:1982.
Calculation equations are :
1)Target mean strength
f’ck =fck + 1.65s
Where
f’ck = target average compressive strength at 28 days
fck = characteristics compressive strength at 28 days, and
s = standard deviation
2)Cement content
Cement content = water content / water-cement ratio
3) Volume Calculations
(a) Volume of concrete
(b) Volume of cement = [Mass of cement] / [Specific Gravity of Cement] x 1/1000
(c) Volume of water = [Mass of water] / [Specific Gravity of water] x 1/1000
(d)Volume of chemical admixture = [Mass of admixture] / [Specific Gravity of admixture] x 1/1000
(e) Volume of all in aggregate =[a-(b+c+d)]
(f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000
(g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
To Calculate the Concrete Mix Design for M35 grade concrete with fly ash:
M35 grade concrete with Fly ash
STEP 1: Stipulations for Concrete design mix
Grade designation :M35
Type of cement :OPC 43 Grade confirming to IS 8112
Type of mineral admixture : Fly ash confirming to IS 3812 (Part 1)
Maximum nominal size of aggregate :20 mm
Minimum cement content :320 kg/m3 (Table 5 of IS 456:2000- Exposure condition
Maximum water-cement ratio :0.45 (Table 5 of IS 456:2000 Exposure condition)
Workability : 100 mm (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 Aggregates
Maximum cement content : 450 kg/m3
Chemical admixture type : Super Plasticizer
STEP 2: TEST DATA FOR MATERIALS
Cement used : OPC 43 Grade conforming IS 8112
Specific gravity of cement :3.15
Fly ash : confirming to IS 3812 (Part 1)
Specific gravity of fly ash : 2.2
Chemical admixture :Super Plasticizer conforming 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 Coarse aggregate :Nil
Sieve analysis: Coarse aggregate
Conforming to Table 2 of IS 383
Sieve analysis:( Fine aggregate ) :Conforming to Grading Zone II of Table 4 of IS 383
STEP 3: TARGET STRENGTH FOR MIX PROPORTIONING
f’ck =fck + 1.65s
Where
f’ck = target average compressive strength at 28 days
fck = characteristics compressive strength at 28 days, and
s = standard deviation
From Table I of IS 10262:2009, Standard Deviation, s = 5 N/mm2.
35 + 1.65 x 5 = 43.25 N/mm2
Target mean strength = 43.25 N/mm2
STEP 4: SELECTION OF WATER-CEMENT RATIO
The maximum water-cement ratio to design M50 grade concrete can be found from Table 5 of IS 456-2000.
Maximum W/C ratio =0.45
Based on experience adopted water cement ratio is .44
0.44<0.45, hence ok
Adopted W/C ratio=0.44
STEP 5: SELECTION OF WATER CONTENT
From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate
186 litre (for 25 to 50 mm slump range)
Clause 4.2 suggests increasing of 3% of water content for every extra 25mm slump from 50mm slump. So a 6% is to be added to it
Estimated water content for 100 mm slump
186+ (6/100)*186 = 197 litre.
(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 20% has been achieved, Hence the arrived water content
197*0.8 = 158 litre
Water required 158 litres
STEP 6: CALCULATION OF CEMENT AND FLY ASH REQUIRED
Adopted w/c Ratio : 0.44
Total cementitious (Cement + fly ash)requirement =158/0.44 = 359 kg/m3
The cementitious content has to be increased in order to attain good workability and strength. The increment required is determined on the basis of experience and research. Here we are increasing cementitious content by 10%
Final cementitious content :359 X 1.10 = 395 kg
From Table 5 of IS 456, Minimum cement content for ‘Severe’ exposure conditions :320 kg
395 kg/m3 > 320 kg/m3 hence ok.
Cementitious material content :395
New water cement ratio :158/395 =0.4
Fly ash content is taken as 30% of the total cementitious content :395 X .3 = 118.5 kg/m3
Cement required : 395 – 118 = 277 kg/m3
Cement quantity saved due to fly ash addition :350-277 = 73 kg/m3
Cementitious material, cement and fly ash required is 395 kg/m3 , 277 kg/m3and 118 kg/m3 and the new water-cement ratio is 0.4 respectively
STEP 7: VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for water-cement ratio of 0.50 is 0.62.
In the present case water-cement ratio is 0.44
Therefore, coarse aggregate for the water-cement ratio of 0.44 is 0.632
For pumpable concrete these values should be reduced up to 10%. Therefore, volume of coarse aggregate is 0.632 x 0.9 =0.568.
Volume of fine aggregate content : 1 – 0.568 =0.431
Volume of fine aggregate and coarse aggregate is 0.431 and .568
STEP 8: MIX CALCULATIONS
The mix calculations as per unit volume of concrete shall be as follows:
a) Volume of concrete :1 m3
b) Volume of cement = [Mass of cement] / [Specific Gravity of Cement] x 1/1000 : (277/3.15) X (1/1000) =0.087m3
c) Volume of fly ash = [Mass of fly ash] / [Specific Gravity of fly ash] x 1/1000 : (118/2.2) X (1/1000) =0.053
d) Volume of water = [Mass of water] / [Specific Gravity of water] x 1/1000 :(158/1) X (1/1000) = 0.158m3
e) Volume of chemical admixture = [Mass of admixture] / [Specific Gravity of admixture] x 1/1000 : (7.6/1.145) X (1/1000) =0.006 m3
f) Volume of all in aggregate = [a-(b+c+d+e)] : [1-(0.087+0.053+0.158+0.006)] = 0.696m3
g) Mass of coarse aggregate= f x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000 : [0.696x 0.568 x 2.74 x 1000 = 1077 kg/m3]
h) Mass of fine aggregate= f x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000 : [0.696x 0.431x 2.74 x 1000 = 822 kg/m3]
STEP 9: MIX PROPORTIONS
Cement : 277 kg/m3
Fly ash : 118 kg/m3
Water : 158 l/m3
Fine aggregate : 822 kg/m3
Coarse aggregate 20mm : 1077 kg/m3
Chemical admixture : 7.18 kg/m3
Water-cement ratio (lowest W/C ratio is selected) : 0.4
Mix Proportion By weight : [1:2.08:2.72]
STEP 10: The slump is measured, The mix proportion shall be reworked for the actual water content and checked for durability requirements
STEP 11: Two more trials having variation of 10% of water-cement ratio shall be carried out and a graph between three water- cement ratios
RESULTS
Mix Proportion by weight of M35 grade of concrete with fly ash is 1:2.08:2.72 and its water-cement ratio was found to be 0.4
2.calculate the concrete mix design for M50 grade concrete with out fly ash
Aim : To calculate the mix design for M50 grade concrete with out using fly ash
INTRODUCTION:
Concrete mix design is the method of finding the precise proportion of cement, sand and aggregates for concrete to achieve the target strength in structures, therefore concrete mix design can be stated as concrete mix in terms of cement: sand: aggregates. The design is done according to the requirements of concrete strength. So, we can achieve the desirable properties of concrete either it is in fresh stage or in hardened stage. The fresh concrete properties like workability, setting time and hardened concrete properties like compressive strength, durability etc. are attained surely by this method. Use of additives like admixtures, retarders etc. other than basic ingredients are used to improve the properties of mix. This project consist of two parts, the first part deals with the design of M50 grade cement with out using fly ash
OBJECTIVE:
The objective of this project is to produce a mix design for M50 grade concrete with out using fly ash. The mix will be prepared as per IS METHOD: Concrete mix proportioning guidelines from IS 10262:2009 and recommented guide lines from IS 10262:1982.
Step 1: Stipulation for proportioning
a. Grade designation : M50
b. Type of cement : OPC grade 43 conforming to IS 8112
c. Maximum nominal sizeof aggregate: 20mm
d. Minimum cement content : 320
`K×[g÷m^3]`
e. Maximum water-cement ratio : 0.45 (Table :5 IS 456-2000,based on exposure condition)
f. Workability :100mm ,slump value of pumpable concrete
g. Exposure condition : Severe ( for reinforced concrete)
h. Method of concrete placing : Pumping
i. Degree of supervision : Good
j. Type of aggregate: Crushed angular aggregate
k. Maximum cement content : 450 kg/m^3.
l. Chemical admixture type : Superplaticizer.
Step 2: Test data for materials
a. Cement used : OPC 43 grade confirming to IS 8112
b. Specific gravity of cement : 3.15
c. Chemical admixture : Superplaticizer conforming to IS 9103
d. Specific gravity of :
Coarse aggregate : 2.74
Fine aggregate : 2.74
e. Water absorption :
Coarse aggregate : 0.5%
Fine aggregate : 1%
f. Free surface moisture
Coarse aggregate : Nil
Fine aggregate : Nil
g. Seive analysis
Coarse aggregate :Conforming to table 2 of IS 383
Fine aggregate : conforming to zone 1 table 4 IS 383
Step 3: To find target mean strength for proportioning
Target mean strength , f'ck =fck +1.65 s
= 50+1.65*5
=58.25 N/mm^2
fck = Characteristic strength
s=standard deviation
Step4:Selection of water cement ratio
From Table :5 of IS 456-2000, by exposure condition
Here severe condition is considered , Maximum water-cement ratio=0.45
Based on experience water- cement ratio =0.4
0.4 <0.45 ,Hence OK.
Step 5: Selection of water content
Maximum water content for 20mm aggregate =186 litres ( Table 2 of IS 1026:2009) for 25mm to 50mm slump range
For 100 mm slump ,= 186+(6/100)*186 =197 litres
As superplaticizer is used, the water content is reduced upto 30%
Based on trials water content reduction of 29% is achieved with plasticizer
Hence arrived water content = 197*0.71 = 140 litres
Step 6: Calculation of cement content
Water - cement ratio = 0.4
Cement content = 140/0.4
=350 kg/m^3
In table 5 of IS 456-2000, the cement content for severe exposure =320 kg/m^3
350 kg/m^3>320kg/m^3.
Hence proved
Step 7: Proportion of volume of coarse aggregate and fine aggregate content
From table 3 of IS 1026:2009 ,volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone 1 ) for water- cement ratio =0.6
In present case the water - cement ratio is 0.4
Therefore the volume of coarse aggregate needs to be increased to decrease
As the 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)
Hence the corrected value of coarse aggregate for the water-cemnt ratio = 0.64
( If coarse aggregate is not of regular type, then the volume of coarse aggregate may be required to be increased suitably ,based on experience)
For pumpable concrete, these are reduced by 10%
Volume of coarse aggregate = 0.64*0.9
= 0.576
Volume of fine aggregate = 1-0.576
=0.424
Step8:Mix calculation
For unit volume of concrete
a. Volume of concrete = 1 m^3
b. Volume of cement = ( Mass of cement / Specific gravity of cement ) *1/1000
=(350/3.15)*1/1000
=0.111 m^3
c. Volume of water = (Mass of water/ Specific gravity of water )*1/1000
= (140/1)*1/1000
=0.140 m^3
d. Volume of chemical admixture = (Mass of admixture/Specific gravity of admixture)*1/1000
= (7.6/1.145)*1/1000
=0.006 m^3
e. Volume of agggregate (fine and coarse)
=a-(b+c+d)
=1-(0.111+0.140+0.006)
=0.743 m^3
f. Mass of coarse aggregate =[ e x Volume of coarse aggregate x Specific gravity of coarse aggregate x 1000]
=[0.743*0.576*2.74*1000]
= 1173 kg/m^3
g. Mass of fine aggregate =[e ×Volume of fine aggregate* Specific gravity of fine aggregate *1000]
= 0.743*0.424*2.74*1000
=863 kg/m^3
Step 9: Mix proportion
Cement = 350 kg/m^3
Water = 140 kg/m^3
Fine aggregate= 863 kg/m^3
Coarse aggregate = 1173 kg/m^3
Chemical admixture = 7 kg/m^3
Water cement ratio =0.4
Mix ratio =1: 2.46: 3.35
Step 10:The slump is measured, The mix proportion shall be reworked for the actual water content and checked for durability requirements
Step 11:Two more trials having variation of 10% of water-cement ratio shall be carried out and a graph between three water- cement ratios
RESULTS
Mix Proportion by weight of M50 grade of concrete with out fly ash is 1:2.46:3.35 and its water-cement ratio was found to be 0.64