Project on Concrete Mix Design for various grades of Concrete
Calculate the Concrete Mix Design for M35 grade concrete with fly ash & M50 grade concrete without Fly ash?
Answer:
AIM AND INTRODUCTION:
the aim of mix design is to decide the proportion of materials which will produce concrete of required properties. The mix proportion should be selected in such a way that the resulting concrete is of desired workability while fresh and it could be placed and compacted easily for the intended purpose.
the mix design is a process tht consists of two interrelated:
1) selection of suitable ingradients.
2)determination of their relative qunatites to produce, as economically as possible concrete of the appropriate worakbility, strength and durability.
PROCEDURES for M35 WITH FLYASH AND M50 WITHOUT FLYASH:
M35 MIX DESIGN OF CONCRETE WITH FLY ASH
- STIPULATIONS FOR PROPORTIONING
a) grade designation: m35
b) type of cement: opc 43 grade
c) Type of ,imeral admixture flyash conforming to is 3812 to part 1
d) maximum nominal of aggregate:20mm
e) maximum W/C ratio : 0.45 (table 5 of IS 456:2000)
f) workability :100mm slump
g) expourse condition : extreme(for RCC)
h) method of concerte placing: pumping
j) degree of supervision : good
k) type of aggregate : crushed angular aggregates
m) maximum cement content: 450kg/m^3
N) admixture : super plasticizer - TEST DATA FOR MATERIALS
a) specific gravity of
1) coarse aggregate :2.74
2) fine aggregate: 2.74
3) cement:3.15
4) fly ash: 2.2
b) water absorption:
1) coarse aggregate :0.5%
2) fine aggregate: 1%
c) free surface moisture:
1) coarse aggregate :nill
2) fine aggregate: nill
d) sieve analysis:
1) coarse aggregate :confirming to all in aggregates of table 2 of IS 383
2) fine aggregate: grading zoneII of table 4 of IS 383 - TARGET STRENGTH FOR MIX PROPORTION:
f'ck=fck+1.65(s)
s=5n/mm^2 table 1 of IS 10262:2009
fck=35n/mm^2
=35+1.65(5)
=43.25n/mm^2 - SELECTION OF WATER CEMENT RATIO
maximum water cemet ratio =0.40 from table 5 of IS 456 adopted for very severe exposure maximum watercement ratio is 0.45. 0.40<0.45 hence ok. - SELECTION WATER CONTENT
from table 2 of IS 102626:2009, maximum water content for 20mm aggregate =186 ltrs (for 25 to 50mm slump range) estimated water content for 100 slump = 186+(6/100)187=
197 ltrs
for super plasticizer water content is reduced upto29%
based on the trails =197-(197-x[29/100])= 140litre - CALUCALTION OF CEMENT
adopted w/c ratio is 0.40
cement content= 140/0.40= 350 kg/m^3
from table 5 for moderete exposure condition 320kg/m^3
350kg/m^3>320kg/m^3
hence ok
To proportion mix containing flyash the following stes are suggested
a) The percentage of flyash needs to be decieded based upon the project requirement and quality of materials.
b) In some cases increases the cementitious material can be warned. increase in cementitious material content an its percentage is based on experience and trail.
in this increase of 10% cementitious material content is considered.
cementitious material content=350*1.1=385kg/m^3
water content=140lg/m^3
W/C ratio= 140/385= 0.364
Fly ash 30% total cemntitious material content = 350*30= 115kg/m^3
cement =385-115 = 270kg/M^3
saving of cement while using flyash= 385-270 =80kg/m^3
Fly ash can be utilized= 115kg/m^3 - PROPORTION OF VOLUME OF CA AND FA
table 3 of IS102626:2009 volume of CA to 20mm and FA to zoneI for w/c ratio of 0.40
in the present case w/c ratiovis 0.44. therefore, volume of CA is required to be increased to decrease the FA content.As the w/c ratio is lower by 0.06. The proportion of volume of CA is increased by 0.02 @ of -/+ 0.01 for every +/- 0.05 change in w/c ratio. therefore corrected proportion of volume of CA for the w/c ratio of0.40=0.64
for pumpable concrete these values should be reduced upto 10%
therefore, volume of CA =0.64*0.9 = 0.576
volume of fine aggregate content = 1-0.576= 0.424. - MIX CALUCATIONS
a)volume of concrete = 1m^3
b)volume of cement= [mass of cement]/{[specific gravity of cement]*1000}
=270/{3.15*1000} = 0.086m^3
c) volume of fly ash=[mass of flyash]/{[specific gravity of flyash]*1000}
=115/2.2*1000 =0.052m^3
c)volume of water= [mass of water]/{[specific gravity of water]*1000}
=140/{1*1000}= 0.14m^3
d) volume of chemical admixture= 0.006m^3
e)volume of all in aggregates = [a-(b+c+d)]
=[1-(0.086+0.052+0.140+0.006)] =0.716m^3
F)mass of CA= e*volume of CA*specific gravity of CA*1000
=0.716*0.576*2.74*1000 = 1130kg/m^3
g)mass of FA= e*volume of FA*specific gravity of FA*1000
=0.716*0.576*2.74*1000 = 831kg/m^3 - MIX PROPORTIONS
cement = 270kg/m^3
fly ash= 115kg/m^3
Water = 140l/m^3
FA = 831kg/m^3
CA = 1130kg/m^3
admixture = 7kg/m^3
w/c ratio = 0.364
MIX PROPORTION : 1:2.15:2.94
M50 MIX DESIGN OF CONCRETE WITHOUT FLY ASH
- STIPULATIONS FOR PROPORTIONING
a) grade designation: m50
b) type of cement: opc 53 grade conforming is 8112
c) maximum nominal of aggregate:20mm
d) maximum W/C ratio : 0.35 (table 5 of IS 456:2000)
f) workability :100mm slump
g) expourse condition : extreme(for RCC)
h) method of concerte placing: pumping
j) degree of supervision : good
k) type of aggregate : crushed angular aggregates
m) maximum cement content: 450kg/m^3
N) admixture : super plasticizer - TEST DATA FOR MATERIALS
a) specific gravity of
1) coarse aggregate :2.74
2) fine aggregate: 2.56
3) cement:3.12
b) water absorption:
1) coarse aggregate :0.5%
2) fine aggregate: 2.5%
c) free surface moisture:
1) coarse aggregate :nill
2) fine aggregate: nill
d) sieve analysis:
1) coarse aggregate :confirming to all in aggregates of table 2 of IS 383
2) fine aggregate: grading zoneII of table 4 of IS 383 - TARGET STRENGTH FOR MIX PROPORTION:
f'ck=fck+1.65(s)
s=5n/mm^2 table 1 of IS 10262:2009
fck=50n/mm^2
=50+1.65(5)
=58.25n/mm^2 - SELECTION OF WATER CEMENT RATIO
maximum water cemet ratio =0.35 from table 5 of IS 456 adopted for very severe exposure maximum watercement ratio is 0.35. 0.35<0.45 hence ok. - SELECTION WATER CONTENT
from table 2 of IS 102626:2009, maximum water content for 20mm aggregate =186 ltrs (for 25 to 50mm slump range) estimated water content for 100 slump = 186+(6/100)186 ltrs =197 kg or lit
for super plasticizer water content is reduced upto27%
based on the trails =197-(197-x[27/100])= 143litre - CALUCALTION OF CEMENT
adopted w/c ratio is 0.35
cement content= 143/0.35= 410 kg/m^3
from table 5 for moderete exposure condition 360kg/m^3
410kg/m^3>360kg/m^3 hence ok - PROPORTION OF VOLUME OF CA AND FA
table 3 of IS102626:2009 volume of CA to 20mm and FA to zoneII for w/c ratio of 0.5=0.62
in the present case w/c ratiovis 0.44. therefore, volume of CA is required to be increased to decrease the FA content.As the w/c ratio is lower by 0.06. The proportion of volume of CA is increased by 0.02 @ of -/+ 0.01 for every +/- 0.05 change in w/c ratio. therefore corrected proportion of volume of CA for the w/c ratio of0.35=0.65
for pumpable concrete these values should be reduced upto 10%
therefore, volume of CA =0.65*0.9 = 0.585
volume of fine aggregate content = 1-0.585= 0.415. - MIX CALUCATIONS
a)volume of concrete = 1m^3
b)volume of cement= [mass of cement]/{[specific gravity of cement]*1000}
=410/{3.12*1000} = 0.131m^3
c)volume of water= [mass of water]/{[specific gravity of water]*1000}
=143/{1*1000}= 0.143m^3
d) volume of chemical admixture= 0.007litres/ m^3
e)volume of all iin aggregates = [a-(b+c+d)]
=[1-(0.131+0.143+0.007)] =0.719m^3
F)Mass of CA= e*volume of CA*specific gravity of CA*1000
=0.719*0.585*2.74*1000 = 1152.48kg/m^3
g)Mass of FA= e*volume of FA*specific gravity of FA*1000
=0.719*0.415*2.56*1000 = 763.86kg/m^3 - MIX PROPORTIONS
cement = 410kg/m^3
Water = 143l/m^3
FA = 763.86kg/m^3
CA = 1152.48kg/m^3
admixture = 7kg/m^3
w/c ratio = 0.35
MIX PROPORTION : 1:1.86:2.81
RESULT:
MIX PROPORTION FOR M35 WITH FLY ASH= 1:2.15:2.94
MIX PROPORTION FOR M50 WITHOUT FLY ASH= 1:1.86:2.81