Project on Concrete Mix Design for various grades of Concrete
PROJECT ON CONCRETE MIX DESIGN
1.MIX DESIGN FOR M35 GRADE CONCRETE WITH FLY ASH
AIM: To calculate the concrete mix design for M35 grade concrete with Fly ash
INTRODUCTION: The process of selecting suitable ingredients of concrete and determining their relative amounts with the objective of producing a concrete of the required, strength, durability, and workability as economically as possible, is termed the concrete mix design. It is stated in terms of cement: fine aggregate: coarse aggregate. The design is done according to the requirements of concrete strength. We can achieve the desirable properties of concrete either in its fresh stage or in its hardened stage. Use of additives like admixtures other than basic ingredients is used to improve the properties of mix, this deal with the design of M35 grade with Fly ash.
OBJECTIVE: To produce a mix design for M35 grade containing fly ash, the mix will be designed according to guidelines from IS 10262:2019, IS 456.; 2000
PROCEDURE:
I.STIPULATIONS FOR PROPORTIONING
1) Grade designation M35
2) Type of mineral admixture: Fly ash confirming to IS 8112
3) Type of mineral admixture Fly ash confirming to IS 3812 (part-1)
4) Maximum nominal size of aggregate-20mm
5) Minimum cement content – 320kg/m^3 (From table 5 of 456: 2000 –Exposure condition)
6) Maximum water cement ratio -0.45 (From table 5 of 456: 2000 –Exposure condition)
7) Workability-100mm (slump value for pumpable concrete)
8) Exposure condition: severe (reinforced cement concrete)
9) Method of concrete placing: pumping
10) Design of supervision: good
11) Type of aggregate: crushed angular aggregate
12) Maximum cement content: 450 kg/m^3
13) Chemical admixture type: super plasticizer
II) TEST DATA FOR MATERIALS
1) Cement used – OPC 43garde confirming to IS 8112
2) Specific gravity of cement -3.15
3) Fly ash confirming to IS 3815 (part 1)
4) Specific gravity of fly ash - 2.2
5) Chemical admixture – Super plasticizer confirming to IS 9103
6) Specific gravity of coarse aggregate – 2.74
Fine aggregate – 2.74
7) Water absorption of coarse aggregate – 0.5%
Fine aggregate - 1.0%
8) Free surface moisture of coarse aggregate – nil
Fine aggregate – nil
9) Sieve analysis coarse aggregate – confirming to table 2 of IS 383
Fine aggregate – confirming to zone I of table 4 IS 383
III) TARGET STRENGTH FOR MIX PROPORTIONING
f’ck = fck+1.65s
Where f’ck – Target average compressive strength at 28days
Fck – Characteristic compressive strength at 28 days
s – Standard deviation
From table 2 of IS 10262: 2019
s = 5.0
Therefore target strength = 35+ (1.651) (5)
=43.25 N/mm^2
IV) SELECTION OF WATER CEMENT RATIO
From table 5 of IS 456:2000 for severe exposure
Maximum water cement ratio is 0.45
From graph I of IS 10262: 2019
Water cement ratio for target strength for 43.25N/mm^2 is 0.38
Minimum water cement ratio should be considered
Therefore water cement ratio 0.38
V) SELECTION OF WATER CONTENT
From table 4 of IS 10262: 2019
Maximum water content for 20mm aggregate = 186 litre (for 25 to 50 mm slump)
Estimated water content for 100mm slump (for additional slump 3% may be added for every 25mm slump)
=186+ (6/100 *186)
=197litre
As super plasticizer used the content can be reduced up to 30%
Based on trials water content reduction of 29% is achieved with plasticizer
Hence the arrived water content = 197 * 0.71
= 140litre
VI) CALUCUCATION OF CEMENT CONTENT
Water cement ratio = 0.38
Cementitious material (cement+ fly ash) = 140/0.38
=368.42kg/m^3
From table of IS 456:2000 minimum cement content for severe exposure condition = 320kg/m^3
368.42 kg/m^3>320 kg/m^3 Hence ok
Now, for proportion a mix containing fly ash the following steps are suggested
a) The percentage of fly ash need to be decided based on project requirement and quality of materials
b) In some cases increase in cementitious material can be warranted increase in cementitious material content and its percentage may be based on experience and trail
(In this case we are taking 10% increase in cementitious material content)
Cementitious material content = 368.42 * 1.10
= 405.26kg/m^3
Water content = 140kg/m^3
Water cement ratio = 140/ 405.26
=0.345
Fly ash @30% total cementitious material content = 405.26 *30%
= 121.57kg/m^3
Cement = 405.26-121.57
=283.69kg/m^3
Saving of cement while using fly ash = 368.42 – 283.69 = 84.73kg/m^3
Fly ash being utilized = 121.57kg/m^3
VII) PROPORTION OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From table 5 of IS 10262: 2019
Volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (zone I) for water cement ratio 0.5 is 0.6
In present case the water cement ratio is 0.38
Therefore, the volume of coarse aggregate needs to be increases to decreases the fine aggregate content
As water cement ratio s is lower by 0.12 the proportion of volume of coarse aggregate is increased by 0.024
(At the rate of + or – 0.01 for every + or – 0.05 change in water cement ratio)
Therefore the corrected volume of coarse aggregate of water cement ratio of 0.38 = 0.624
For pumpable concrete these values are reduced by 10%
Therefore volume of coarse aggregate = 0.624*0.9
= 0.561
Volume of fine aggregate = 1-0.561
=0.439
VIII) MIX CALUCULATIONS
The mix calculation per unit volume of concrete shall be as following
a) Volume of concrete=1m^3
b) Volume of cement= (mass of cement/specific gravity of cement)*(1/1000)
= (286.69/3.15)*(1/1000)
=0.09m^3
c) Volume of Fly ash= (mass of Fly ash /specific gravity of cement)*(1/1000)
= (121.57/2.2)*(1/1000)
=0.051m^3
d) Volume of water= (mass of water/specific gravity of water)*(1/1000)
= (140/1)*(1/1000)
=0.140m^3
e) Volume of chemical admixture= (mass of chemical admixture/specific gravity of admixture)*(1/1000)
= (8.1/1.145)*(1/1000)
=0.007m^3
Mass of chemical admixture=2% of cementitious material
=405.26*(2%)
=8.1
f) Volume of aggregate (FA+CA) = (a-(b+c+d+e))
=1-(0.09+0.055+1.140+0.007)
=0.708m^3
Mass of Coarse aggregate = f*volume of coarse aggregate*specific gravity of coarse aggregate*1000
= 0.708*0.561*2.74*1000
= 1088.29kg/m3
Mass of fine aggregate = f*volume of coarse aggregate*specific gravity of coarse aggregate*1000
=0.708*0.439*2.74*1000
=851kg/m^3
IX) MIX PROPORTION FOR M35 GRADE WITH FLYASH
Cement = 283.69kg/m^3
Fly ash = 121.57kg/m^3
Water = 140kg/m^3
Fine aggregate = 851kg/m^3
Coarse aggregate = 1088.29kg/m^3
Chemical admixture = 8.1kg/m^3
Water cement ratio = 0.345
Mix ratio = cement: fly ash: fine aggregate: coarse aggregate
=283.69:121.27:851:1088.29
=1:0.42:2.9:3.8
RESULT:
Mix proportion of M35 grade of concrete with fly ash is 1: 0.42:0.9:3.8 and its water cement ratio is found to be 0.345
Note: the mix design are always determined by trial error method so two more trails having variation of 10% 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 strength for field trails.
2.MIX DESIGN FOR M50 GRADE CONCRETE
AIM: To calculate the concrete mix design for M50 grade concrete
INTRODUCTION: The process of selecting suitable ingredients of concrete and determining their relative amounts with the objective of producing a concrete of the required, strength, durability, and workability as economically as possible, is termed the concrete mix design. It is stated in terms of cement: fine aggregate: coarse aggregate. The design is done according to the requirements of concrete strength. We can achieve the desirable properties of concrete either in its fresh stage or in its hardened stage. Use of additives like admixtures other than basic ingredients is used to improve the properties of mix, this deal with the design of M50grade.
OBJECTIVE: To produce a mix design for M50 grade, the mix will be designed according to guidelines from IS 10262:2019, IS 456:2000
PROCEDURE:
I.STIPULATIONS FOR PROPORTIONING
1) Grade designation M50
2) Type of cement: OPC 43 grade (IS 8112)
3) Exposure condition – Extreme (R.C.C)
4) Minimum cement content 360 kg/m^3 (From table 5 of IS 456: 2000 based on exposure condition)
6) Minimum water cement ratio 0.4 (From table 5 of IS 456: 2000 based on exposure condition)
7) Workability: 100mm (slump value for pumpable concrete)
8) Maximum nominal size of aggregate 20mm
9) Method of concrete placing: pumping
10) Degree of super vision: good
11) Type of aggregate: crushed angular aggregate
12) Maximum cement content: 450kg/m^3
13) Chemical admixture type: super plasticizer
II) TEST DATA FOR MATERIALS
1) Cement used – OPC 43garde confirming to IS 8112
2) Specific gravity of cement -3.15
3) Chemical admixture – Super plasticizer confirming to IS 9103
4) Specific gravity of coarse aggregate – 2.74
Fine aggregate – 2.74
5) Water absorption of coarse aggregate – 0.5%
Fine aggregate - 1.0%
6) Free surface moisture of coarse aggregate – nil
Fine aggregate – nil
7) Sieve analysis coarse aggregate – confirming to table 2 of IS 383
Fine aggregate – confirming to zone I of table 4 IS 383
III) TARGET STRENGTH FOR MIX PROPORTIONING
f’ck = fck+1.65s
Where f’ck – Target average compressive strength at 28days
Fck – Characteristic compressive strength at 28 days
S – Standard deviation
From table 2 of IS 10262: 2019
S = 5.0 for M50 grade
Therefore target strength = 50+ (1.65) (5)
=58.25 N/mm^2
IV) SELECTION OF WATER CEMENT RATIO
From table 5 of IS 456:2000 for extreme exposure
Maximum water cement ratio is 0.40
From graph I of IS 10262: 2019
Water cement ratio for target strength for 58.25N/mm^2 is 0.34
Minimum water cement ratio should be considered
Therefore water cement ratio 0.34
V) SELECTION OF WATER CONTENT
From table 4 of IS 10262: 2019
Maximum water content for 20mm aggregate = 186 litre (for 25 to 50 mm slump)
Estimated water content for 100mm slump (for additional slump 3% may be added for every 25mm slump)
=186+ (6/100 *186)
=197litre
As super plasticizer used the content can be reduced up to 30%
Based on trials water content reduction of 29% is achieved with plasticizer
Hence the arrived water content = 197 * 0.71
= 140litre
VI) CALUCUCATION OF CEMENT CONTENT
Water cement ratio=0.34
Cement content=water content/0.34
=140/0.34
=411.76kg/m^3
Form table 5 of IS 456:2000 minimum cement content for extreme exposure condition=360kg/m^3
411.76>360kg/m^3 Hence ok
VII) PROPORTION OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From table 5 of IS 10262: 2019
Volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (zone I) for water cement ratio 0.5 is 0.6
In present case the water cement ratio is 0.34
Therefore, the volume of coarse aggregate needs to be increases to decreases the fine aggregate content
As water cement ratio s is lower by 0.16 the proportion of volume of coarse aggregate is increased by 0.032
(At the rate of + or – 0.01 for every + or – 0.05 change in water cement ratio)
Therefore the corrected volume of coarse aggregate of water cement ratio of 0.34 = 0.632
For pumpable concrete these values are reduced by 10%
Therefore volume of coarse aggregate = 0.632*0.9
= 0.568
Volume of fine aggregate = 1-0.568
=0.432
VIII) MIX CALUCULATIONS
The mix calculation per unit volume of concrete shall be as following
a) Volume of concrete=1m^3
b) Volume of cement= (mass of cement/specific gravity of cement)*(1/1000)
= (411.76/3.15)*(1/1000)
=0.130m^3
c) Volume of water= (mass of water/specific gravity of water)*(1/1000)
= (140/1)*(1/1000)
=0.140m^3
d) Volume of chemical admixture= (mass of chemical admixture/specific gravity of admixture)*(1/1000)
= (8.23/1.145)*(1/1000)
=0.007m^3
Mass of chemical admixture=2% of cementitious material
=411.76*(2%)
=8.23
e) Volume of aggregate (FA+CA) = (a-(b+c+d))
=1-(0.130+0.140+0.007)
=0.723m^3
f) Mass of Coarse aggregate = e*volume of coarse aggregate*specific gravity of coarse aggregate*1000
= 0.723*0.568*2.74*1000
= 1125.22kg/m3
Mass of fine aggregate = e*volume of coarse aggregate*specific gravity of coarse aggregate*1000
=0.723*0.432*2.74*1000
=855.8kg/m^3
IX) MIX PROPORTION FOR M50 GRADE
Cement = 411.76kg/m^3
Water =140kg/m^3
Fine aggregate =855.8kg/m^3
Coarse aggregate =1125.22kg/m^3
Chemical admixture =8.23kg/m^3
Water cement ratio =0.34
Mix ratio = cement: fine aggregate: coarse aggregate
= 411.76:855.8:1125.22
=1:2.07:2.73
RESULT:
Mix proportion of M50 grade of concrete is 1:2.07:2.73and its water cement ratio is found to be 0.34
Note: the mix design are always determined by trial error method so two more trails having variation of 10% 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 strength for field trails.