Project on Concrete Mix Design for various grades of Concrete
AIM : To calculate the concrete mix design for M35 grade concrete with fly ash
introduction: Mix design calculate procedure is the same when either GGBS or fly ash is used , the only change will be specific gravity of the admixture. the specific gravity of the fly ash ranges from 2.1 to 3 whereas the specific ggravity of GGBS is 2.85 superplasticizers are required for all high strength concrete to get good workability and good strength in concrete.
EQUATIONS: Traget mean strength f'ck= fck+1.65s , f 'ck = traget mean strength . fck = compressive strength at 28 days of concrete s = standard deviation
- volume of cement = mass of cement/ specific gravity of cement * 1/1000
- volume of water= mass of water / specific gravity of water *1/1000
- volume of chemichal admixture= mass of chemical admixture /specific gravity of chemical admixture *1/1000
- volume of fly ash = mass of fly ash/specific gravity *1/1000
- volume of concrete = 1m^3
- volume of aggrgate = [ vol.of concrete - vol.of cement +vol.of fly ash +vol.of water+vol.of admixture]
- volume of coarse agrregate = vol.of aggregate *vol.of coarse aggregate *specific gravity of coarse aggregate*1000
- mass of fine aggregate = vol.of aggregate *vol.of fine aggregate *specific gravity of fine aggregate *1000
CODES FOR CONCRETE MIX DESIGN :
- IS 10262:2009
- IS 456:2000
- IS 8112
- IS 9103
- IS 3812 (part -1)
OBJECTIVES :
- The main objective is to produce concrete as economically as possible
- to achieve desired workability durability and minimum strength of M35 grade concrete
PROCEDURE & CALCULATION:
- Target mean strength : F' ck = f ck+1.65
fck = 35N/mm^(m35)
table -1 IS 10262 :2009
s= 5N/mm^2 f'ck= 35+(1.65 *5) =43.25N/mm2
2. SELECTION OF WATER CEMENT RATIO:
given, M35
assume : Exposure condition : extreme
table -5 - IS 456 :2000
therefore, Extreme = w/c ratio =0.40
M35 = w/c ratio = 0.45 lower the water cement ratio better the workability 0.40 <0.45
water cement ratio=0.45
minimum cement content = 360kg /mm^2
3. SELECTION OF WATER CONTENT :
assume ; nominal size of aggregare = 20mm table 2 - IS 10262:2009
minimum water content = 186litrs slump ranges from 25 to 50 mm as superplasticizers (20% reduces)
186*80*100=148.8
( 100-20=80) water content =149 liters
4. CALCULATION OF CEMENTITIOUS (CEMENT + FLY ASH)
water cement ratio= w/c = 0.40
water content = w= 149kg
cementitious content = c= 149/0.40 = 372.5
=370kg/m^3
minimum cement =360kg/m^3 360 < 370/m^3 increase by 10% 370 *0.10 +370 = 407kg /m^3
w = 149kg
water cement ratio=149/407= 0.366
Fly ash at 30%total cementitiuos material content = 407*30/100 = 122kg/m^3
cement cordinary portland cement =407 -122 = 285kg/m
saving of cement while using fly ash = 370 -285 =85 kg/m^3
fly ash = 122kg/m^3
5.VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE :
fine aggregate are sieved accroding to zone 1 of table 4 IS383
coarse aggregate are sieved accroding to table 2 IS 383 accroding table 3 IS 10262:2009 Norminal size of aggregates=20m
fine aggregate (zone 1)
therofore, volume of coarse aggregate = 0.60
water cement ratio = 0.4
so, volume of coarse aggate = 0.62
vol.of fine aggregate = 1-0.62=0.38
6. MIX CALCULATION:
1.vol.of concrete =1m^3
2.vol.of cement = 285/3.15*1/1000 = 0.090m^3
3. vol.of fly ash = 122/2.2*1/1000 = 0.055m^3
4. vol.of water =149/1*1/1000 = 0.149m^3
5. vol.of admixture = 7.6/1.145*1/1000 = 0.006m^3
6. vol.of coarse aggregate and fine aggregate = a- (b+c+d+e) = 1 -(0.090+0.55+0.149+0.006) = 0.7m^3
7. mass of coarse aggregate = 0.7*0.62*2.74*1000 = 1189.16kg/m^3
8. Mass of fine aggate = 0.7*0.38*2.74*1000 = 728kg /m^3
RESULT AND CONCLUSION:
TRIAL MIX:
cement = 285 kg/m^3
Fly ash = 122kg /m^3
water = 149kg /m^3
coarse aggregate = 1189kg/m^3
fine aggregate = 728kg/m^3
chemical admixture = 7.6kg/m^3
water cement ratio= 0.366
trail mix ratio: 285:728:1189 = 1:2.5:4.17 (C:FA:CA)
conclusion: 1. This trailmix ratios should match the durabitlity , minimum strength of M35grade concrete
2.if ti dones not statisfiy the above criteria two or more trails for increase of 10% should be done
AIM: To calculate M 50 grade without fly ash
Equations :
raget mean strength f'ck= fck+1.65s , f 'ck = traget mean strength . fck = compressive strength at 28 days of concrete s = standard deviation
- volume of cement = mass of cement/ specific gravity of cement * 1/1000
- volume of water= mass of water / specific gravity of water *1/1000
- volume of chemichal admixture= mass of chemical admixture /specific gravity of chemical admixture *1/1000
- volume of fly ash = mass of fly ash/specific gravity *1/1000
- volume of concrete = 1m^3
- volume of aggrgate = [ vol.of concrete - vol.of cement +vol.of fly ash +vol.of water+vol.of admixture]
- volume of coarse agrregate = vol.of aggregate *vol.of coarse aggregate *specific gravity of coarse aggregate*1000
- mass of fine aggregate = vol.of aggregate *vol.of fine aggregate *specific gravity of fine aggregate *1000
CODES FOR CONCRETE MIX DESIGN :
- IS 10262:2009
- IS 456:2000
- IS 8112
- IS 9103
- IS 3812 (part -1)
Objectives: 1. the main objective is to produce concrete as economically as possible
2. to achieve desired workability durability and minimum strength of M50 grade concrete
PROCEDURE & CALCULATION:
- Target mean strength : F' ck = f ck+1.65
fck = 35N/mm^(m35)
table -1 IS 10262 :2009
s= 5N/mm^2 f'ck= 50+(1.65 *5) =58.28N/mm2
2. SELECTION OF WATER CEMENT RATIO:
given, M50
assume : Exposure condition : extreme
table -5 - IS 456 :2000
therefore, Extreme = w/c ratio =0.40
M35 = w/c ratio = 0.45 lower the water cement ratio better the workability 0.40 <0.45
water cement ratio=0.45
minimum cement content = 360kg /mm^2
3. SELECTION OF WATER CONTENT :
assume ; nominal size of aggregare = 20mm table 2 - IS 10262:2009
minimum water content = 186litrs slump ranges from 25 to 50 mm as superplasticizers (20% reduces)
186*80*100=148.8
( 100-20=80) water content =149 liters
4. CALCULATION OF CEMENTITIOUS (CEMENT + FLY ASH)
water cement ratio= w/c = 0.40
water content = w= 149kg
cementitious content = c= 149/0.40 = 372.5
=370kg/m^3 (hence ok)
5.VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE :
fine aggregate are sieved accroding to zone 1 of table 4 IS383
coarse aggregate are sieved accroding to table 2 IS 383 accroding table 3 IS 10262:2009 Norminal size of aggregates=20m
fine aggregate (zone 1)
therofore, volume of coarse aggregate = 0.60
water cement ratio = 0.4
so, volume of coarse aggate = 0.62
vol.of fine aggregate = 1-0.62=0.38
6. MIX CALCULATION:
1.vol.of concrete =1m^3
2.vol.of cement = 373/3.15*1/1000 = 0.118m^3
3.vol.of water =149/1*1/1000 = 0.149m^3
4. vol.of admixture = 7.6/1.145*1/1000 = 0.006m^3
5. vol.of coarse aggregate and fine aggregate = a- (b+c+d+e) = 1 -(0.118+0.149+0.006) = 0.727m^3
6. mass of coarse aggregate = 0.727*0.38*2.74*1000 = 1235.02kg/m^3
7. Mass of fine aggate = 0.727*0.38*2.74*1000 = 756.9kg /m^3
RESULT AND CONCLUSION:
TRIAL MIX:
cement = 285 kg/m^3
water = 149kg /m^3
coarse aggregate = 1235.02kg/m^3
fine aggregate = 756.9kg/m^3
chemical admixture = 7.6kg/m^3
water cement ratio= 0.40
trial mix ratio: 373:756.9:1235.02 = 1:2.02:3.31 (C:FA:CA)
conclusion:
1. This trial mix ratio should match the workability , durability minimum strength of M50 grade concrete
2. if it does not satifiy the above criteria two or more trials for increase of 10% should be done