Project on Concrete Mix Design for various grades of Concrete
Part 1.
AIM: To Calculate the Concrete Mix Design for M35 grade concrete with fly ash & M50 grade concrete without 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 as a part of it and second part is the design of M50 grade concrete without fly ash.
OBJECTIVES:
- The main objective is to produce concrete as economically as possible
- To achieve desired workability, durability and minimum strength of M35 grade concrete.
DATA COLLECTION:
- Grade of Concrete: M35
- Type of exposure: Extreme
- Size of coarse aggregate: 20mm
- Fine aggregate zone: Zone III
- Specific gravity of cement: 3.15
- Specific gravity of water: 1
- Specific gravity of admixture: 1.145
- Specific gravity of fly ash: 2.2
- Specific gravity of Coarse aggregate: 2.74
- Specific gravity of Fine aggregate: 2.74
PROCEDURE AND CALCULATION:
1.TARGET MEAN STRENGTH:-
f’ck= fck +1.65 s
f’ck = target mean strength
fck= compressive strength at 28 days of concrete
s = standard deviation ( IS 10262:2009 , table -1)
F’ck = fck + 1.65*s
fck= 35 N/mm^2 (M35 )
s = 5 N/mm^2
f’ck= 35 +1.65*5
= 43.25 N/mm^2
2.SELECTION OF WATER CEMENT RATIO :
Given :
Exposure condition : Extreme ( for reinforced concrete) (As per 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 = 0.40
Minimum cement content = 360 kg/m^3 (As per Table 5 – IS 456 : 2000)
3.SELECTION OF WATER CONTENT:
Assume :
Nominal size of aggregates= 20 mm ( As per Table 2 -IS 10262: 2009)
Minimum water content = 186 litres or kg ( As per Table 2 -IS 10262: 2009)
Slump ranges from 25 to 50 mm
As superplasticizers (20 % reduced)
= 186 x 80/100 = 148.8 (100-20 = 80)
Hence, Water content = W = 149 lit/kg
4.CALCULATION OF CEMETITIOUS CONTENT ( CEMENT + FLY ASH):
Water cement ratio = w/c= 0.40
Water content = W = 149 kg
Cementitious content = c=149/0.40 = 372.5 = 370 kg/m^3
Minimum cement content = 360 kg/m^3 (As per Table 5 – IS 456 : 2000)
360< 370 kg/m^3 ( hence okay )
370 x (10/100) + 370 = 407 kg/m^3 (Increase by 10 % )
Water content = W = 149 kg
Water cement ratio = 149/407 = 0.366
Fly ash at 30 % total cementitious material content
= 407 x 30/100 = 122 kg/m^3
Cement (ordinary Portland cement )
= 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 ,
Table 3 IS 10262: 2009
Nominal size of aggregates = 20 mm
Fine aggregates ( zone 1)
Therefore ,
Volume of coarse aggregate = 0.60
Water cement ratio = 0.4
( +/- 0.01 for every +/- 0.005)
So, volume of coarse aggregate = 0.62
Volume of fine aggregate = 1-0.62 = 0.38
6.MIX CALCULATION :
1.Volume of concrete = 1m^3
- Volume of cement : (mass of cement /specific gravity of cement )x1 /1000
Volume of cement = (285 / 3.15) x1/1000= 0.090 m^3
- Volume of fly ash : (mass of fly ash/specific gravity of fly ash )x 1/1000
Volume of fly ash = ( 122/2.2) x1/1000=0.055 m^3
- Volume of water : ( mass of water /specific gravity of water ) x1 /1000
Volume of water = ( 149/1)x 1/1000=0.149 m^3
- Volume admixtures : ( mass of admixture / specific gravity of chemical admixture )x 1/1000
Volume of admixture = ( 7.6/ 1.145)x1/1000=0.006 m^3
- Volume of coarse aggregate and fine aggregate: ( volume of concrete -( volume of cement +volume of fly ash + volume of water + volume of admixture )
Volume of coarse aggregate and fine aggregate: ( 1 -( 0.090 +0.055 + 0.149+ 0.006 ))=(1-0.3)
=0.7 m^3 (Volume of aggregate)
- Mass of coarse aggregates: (volume of aggregate)x(volume of coarse aggregate x specific gravity of coarse aggregate) x1000
Mass of coarse aggregate = 0.7 x 0.62 x 2.74 x1000 = 1189.16 kg/m^3
8.Mass of fine aggregate : (volume of aggregate) x( volume of fine aggregate) x (specific gravity of fine aggregate)x1000
Mass of fine aggregate = 0.7 x 0.38 x 2.74 x1000 = 728 kg/m^3
7.RESULTS AND CONCLUSION :
TRIAL MIX
Cement = 285 kg/m^3
Fly ash = 122 kg/m^3
Water = 149 lit/kg
Coarse aggregate = 1189 kg/m^3
Fine aggregate = 728 kg/m^3
Admixture = 7.6 kg/m^3
Water cement ratio = 0.40
Trial mix ratio : 285 :728 : 1189 = 1: 2.55 : 4.17 ( C: FA: CA)
Mix Proportion by weight of M35 grade of concrete with fly ash is 1:2.55:4.17 and its water-cement ratio was found to be 0.40
Part2
OBJECTIVES:
- The main objective is to produce concrete as economically as possible
- To achieve desired workability, durability and minimum strength of M50 grade concrete
DATA COLLECTION:
- Grade of Concrete: M50
- Exposure condition : Extreme
- Size of coarse aggregate: 20mm
- Fine aggregate zone: Zone III
- Specific gravity of cement: 3.15
- Specific gravity of water: 1
- Specific gravity of admixture: 1.145
- Specific gravity of Coarse aggregate: 2.74
- Specific gravity of Fine aggregate: 2.74
PROCEDURE AND CALCULATION:
1.TARGET MEAN STRENGTH:-
f’ck= fck +1.65 s
f’ck = target mean strength
fck= compressive strength at 28 days of concrete
s = standard deviation ( IS 10262:2009 , table -1)
F’ck = fck + 1.65*s
fck= 50 N/mm^2 (M50 )
s = 5 N/mm^2
f’ck= 50 +1.65*5
= 58.25 N/mm^2
2.SELECTION OF WATER CEMENT RATIO :
Given :
Exposure condition : Extreme ( for reinforced concrete) (As per Table 5 – IS 456 : 2000)
Therefore,
Extreme= w/c ratio= 0.40
M50 = w/c ratio= 0.40
Lower the water cement ratio better the workability
Water cement ratio = 0.40
Minimum cement content = 360 kg/m^3 (As per Table 5 – IS 456 : 2000)
3.SELECTION OF WATER CONTENT:
Assume :
Nominal size of aggregates= 20 mm ( As per Table 2 -IS 10262: 2009)
Minimum water content = 186 litres or kg ( As per Table 2 -IS 10262: 2009)
Slump ranges from 25 to 50 mm
As superplasticizers (20 % reduced)
= 186 x 80/100 = 148.8 (100-20 = 80)
Hence, Water content = W = 149 lit/kg
4.CALCULATION OF CEMETITIOUS CONTENT
Water cement ratio = w/c= 0.40
Water content = W = 149 kg
Cementitious content = c=149/0.40 = 372.5 = 373 kg/m^3
Minimum cement content = 360 kg/m^3 (As per Table 5 – IS 456 : 2000)
360< 373 kg/m^3 ( hence okay )
Cement(OPC)= 373 kg/m^3
5.VOLUME OF COARSE AGGREGATES AND FINE AGGREGATES:
According ,
Table 3 IS 10262: 2009
Nominal size of aggregates = 20 mm
Fine aggregates ( zone 1)
Therefore ,
Volume of coarse aggregate = 0.60
Water cement ratio = 0.4
(+/- 0.01 for every +/- 0.005)
So, volume of coarse aggregate = 0.62
Volume of fine aggregate = 1-0.62 = 0.38
6.MIX CALCULATION :
1.Volume of concrete = 1m^3
- Volume of cement : (mass of cement /specific gravity of cement )x1 /1000
Volume of cement = (373/ 3.15) x1/1000= 0.118 m^3
- Volume of water : ( mass of water /specific gravity of water ) x1 /1000
Volume of water = ( 149/1)x 1/1000=0.149 m^3
- Volume admixtures : ( mass of admixture / specific gravity of chemical admixture )x 1/1000
Volume of admixture = ( 7.6/ 1.145)x1/1000=0.006 m^3
- Volume of coarse aggregate and fine aggregate: ( volume of concrete -( volume of cement + volume of water + volume of admixture )
Volume of coarse aggregate and fine aggregate: ( 1 -( 0.118 +0.149+ 0.006 ))=(1-0.273)
=0.727 m^3 (Volume of aggregate)
- Mass of coarse aggregates: (volume of aggregate)x(volume of coarse aggregate x specific gravity of coarse aggregate) x1000
Mass of coarse aggregate = 0.727 x 0.62 x 2.74 x1000 = 1235.02 kg/m^3
7.Mass of fine aggregate : (volume of aggregate) x( volume of fine aggregate) x (specific gravity of fine aggregate)x1000
Mass of fine aggregate = 0.727x 0.38 x 2.74 x1000 = 756.95 kg/m^3
7.RESULTS AND CONCLUSION :
TRIAL MIX
Cement = 373 kg/m^3
Water = 149 kg
Coarse aggregate = 1235.02 kg/m^3
Fine aggregate = 756.95 kg/m^3
Admixture = 7.6 kg/m^3
Water cement ratio = 0.40
Trial mix ratio : 373:756.95:1235.02= 1:2.02:3.31 ( C: FA: CA)
Mix Proportion by weight of M50 grade of concrete without fly ash is 1:2.02:3.31 and its water-cement ratio was found to be 0.40.