Project on Concrete Mix Design for various grades of Concrete
CALCULATION OF CONCRETE MIX DESIGN FOR M35 GRADE CONCRETE WITH FLY ASH
Aim: To calculate the concrete mix design for M35 grade concrete with fly ash.
Formulae to be used:
- Target mean strength=ft/f'ck= fck + 1.65 s
where fck=compressive strength at 28 days of concrete, s=standard deviation(from IS 10262:2009, table 1)
- 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 chemical admixture=(mass of chemical admixture/specific gravity of chemical admixture)*(1/1000)
- Volume of fly ash=(mass of fly ash/specific gravity of fly ash)*(1/1000)
- Volume of concrete= 1m^3
- Volume of aggregates= volume of concrete- (volume of cement+volume of fly ash+ volume of water+volume of chemical admixture)
- Mass of C.A.= Volume of aggregate * volume of C.A.* specific gravity of C.A* 1000
- Mass of F.A.= Volume of aggregate * volume of F.A.* specific gravity of F.A* 1000
Codes used for concrete mix design:
IS 10262:2009, IS 456:2000, IS3812 (Part 1)
Objective:
To achieve desired workability,durability and minimum strength of M35 grade of concrete and also produce this concrete in economical way.
Calculations:
- Target mean strength=ft/f'ck= fck + 1.65 s =35+(1.65*5)=43.25 n/mm^2
where, s=5 (as per IS 10262:2009,table 1)
2.Selection of water cement ratio:
For M35 grade of concrete, lets consider extreme exposure condition, therefore from table 5, IS 456:2000,
w/c ratio for M35= 0.45.
Lower the w/c ratio better the workability, 0.4< 0.45. hence w/c ratio=0.4
Minimum cement content= 360 kg/m^3
3.Selection of water content:
- Minimum water content=186 lit
- slump ranges from 25 to 50 mm (20% reduced as superplasticizers)=186 *80/100=148.8~149 lit
4.Calculations of cementitious material (cement=fly ash)
- water content= 149 kg
- w/c ratio=0.4
- cementitious content=c=149/0.40=372.5= 370 kg/m^3
- Minimum cement content= 360 kg/m^3, 360<370 kg/m^3 hence O.K.
incresed by 10%, 370 + 370*0.10= 407 kg/m^3
Fly ash at 30% total cementitious material content=407 * 30/100= 122 kg/m^3
- cement(OPC)=407-122= 285 kg/m^3
saving of cement while using fly ash=370-285=85 kg/m^3, fly ash= 122 kg/m^3
5.Volume of coarse aggregates and fine aggregates-
According to IS 10262:2009,table 3, nominal size of aggregate=20mm
therefore volume of coarse aggregate=0.6
W/C ratio= 0.4(+/-0.01 for every +/-0.005), so volume of C.A=0.62, volume of fine aggregate= 1-0.62=0.38
6.Mix Calculation:
- Volume of concrete=1m^3
- Volume of cement=(285/3.15)*(1/1000)=0.090 m^3
- Volume of water=(149/1)*(1/1000)=0.149 m^3
- Volume of chemical admixture=(7.6/1.145)*(1/1000)=0.006 m^3
- Volume of fly ash=(122/2.2)*(1/1000)=0.055 m^3
- Volume of aggregates= volume of concrete- (volume of cement+volume of fly ash+ volume of water+volume of chemical admixture)=1-(0.090+0.055+0.149+0.006)=0.7m^3
- Mass of C.A.= 0.7 * 0.62* 2.74* 1000= 1189.16 kg/m^3
- Mass of F.A.=0.7*0.38*2.74*1000=728 kg/m^3
Results and calculation:
- cement=285 kg/m^3
- fly ash=122 kg/m^3
- water= 149 liters
- C.A.= 1189 kg/m^3
- F.A.= 728 kg/m^3
- chemical admixture=7.6 kg/m^3
- water cement ratio=0.366
- Trial mix ratio : 285:728:1189 =1: 2.55 : 4.17= (C:FA:CA)
If it does not achieve the desired criteria, two or more trials for increase of 10% should be done.
CALCULATION OF M50 GRADE CONCRETE WITHOUT FLY ASH
Aim: To calculate the concrete mix design for M50 grade concrete without fly ash.
Formulae to be used:
- Target mean strength=ft/f'ck= fck + 1.65 s
where fck=compressive strength at 28 days of concrete, s=standard deviation(from IS 10262:2009, table 1)
- 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 chemical admixture=(mass of chemical admixture/specific gravity of chemical admixture)*(1/1000)
- Volume of fly ash=(mass of fly ash/specific gravity of fly ash)*(1/1000)
- Volume of concrete= 1m^3
- Volume of aggregates= volume of concrete- (volume of cement+volume of fly ash+ volume of water+volume of chemical admixture)
- Mass of C.A.= Volume of aggregate * volume of C.A.* specific gravity of C.A* 1000
- Mass of F.A.= Volume of aggregate * volume of F.A.* specific gravity of F.A* 1000
Codes used for concrete mix design:
IS 10262:2009, IS 456:2000, IS3812 (Part 1)
Objective:
To achieve desired workability,durability and minimum strength of M50 grade of concrete and also produce this concrete in economical way.
Calculations:
- Target mean strength=ft/f'ck= fck + 1.65 s =50+(1.65*5)=58.25 n/mm^2
where, s=5 (as per IS 10262:2009,table 1)
2.Selection of water cement ratio:
For M50 grade of concrete, lets consider extreme exposure condition, therefore from table 5, IS 456:2000,
w/c ratio for M50= 0.40
Lower the w/c ratio better the workability, hence w/c ratio=0.4
Minimum cement content= 360 kg/m^3
3.Selection of water content:
- Minimum water content=186 lit
- slump ranges from 25 to 50 mm (20% reduced as superplasticizers)=186 *80/100=148.8~149 lit
4.Calculations of cement content:
water content= 149 kg
- w/c ratio=0.4
- cementitious content=c=149/0.40=372.5= 373 kg/m^3
- Minimum cement content= 360 kg/m^3, 360<373 kg/m^3 hence O.K.
5.Volume of coarse aggregates and fine aggregates-
According to IS 10262:2009,table 3, nominal size of aggregate=20mm
therefore volume of coarse aggregate=0.60
W/C ratio= 0.4(+/-0.01 for every +/-0.005), so volume of C.A=0.62, volume of fine aggregate= 1-0.62=0.38
6.Mix Calculation:
- Volume of concrete=1m^3
- Volume of cement=(373/3.15)*(1/1000)=0.118 m^3
- Volume of water=(149/1)*(1/1000)=0.149 m^3
- Volume of chemical admixture=(7.6/1.145)*(1/1000)=0.006 m^3
- Volume of aggregates= volume of concrete- (volume of cement+ volume of water+volume of chemical admixture)=1-(0.118+0.149+0.006)=0.727 m^3
- Mass of C.A.= 0.727 * 0.62* 2.74* 1000= 1235.0276 kg/m^3
- Mass of F.A.=0.727 *0.38 *2.74*1000=756.95 kg/m^3
Results and calculation:
- cement=373 kg/m^3
- water= 149 liters
- C.A.= 1235.027 kg/m^3
- F.A.= 756.97 kg/m^3
- chemical admixture=7.6 kg/m^3
- water cement ratio=0.4
- Trial mix ratio = 373 : 756.97 :1235.0.27 =1: 2.03 : 3.31= (C:FA:CA)