Project on Concrete Mix Design for various grades of Concrete
concrete mix design for M35 grade concrete with fly ash:
i)stipulations for proportioning of M35 grade concrete-
a) grade of designation- M35
b) type of cement - OPC 53
c)type of admixture- fly ash
d)maximum nominal size of aggregate - 20mm
e)minimum cement content - 340kg (table 5-IS456)
f)maximum cement content- 450(as per code)
g)partial replacement of cement by fly ash- 30%( as per requirement)
h)maximum W/C ratio- 0.45(table5:IS456)
I)workability-100mm
j) chemical admixture - PCS type
ii)test data for materials -
a)cement used -OPC 53-confirming to IS 8112
b)specific gravity of cement- 3.15- test-IS:2720
c)mineral admixture -fly ash -confirming to IS12089
d)specific gravity of fly ash - 2.90
f)chemical admixture- @0.6% - IS9103
e)specific gravity of - - test -IS2386
coarse aggregate - 2.74
fine aggregate -2.74
admixture PCE based -1.12
g) water absorption - test-IS 2386
coarse aggregate - 0.5%
fine aggregate - 1%
h)sieve analysis - test -IS2386
Coarse aggregate _-confirming to table 2- IS383
Fine aggregate - zone II- confirming to table4- IS 383
iii)target strength for mix proportions of M35 grade concrete:
Fck=fck+1.65s( "s" from table 1- IS 10262)
Fck =35+1.65*5=43.25N/mm2
iv) selection of water - cement ratio :
maximum W/C ratio = 0.45(table 5-IS 456)
adopted W/C ratio =o.45
v)selection of water content:
maximum water content =186L (table 2- is1026)
above water content is for 25 to 50mm slump , but we need 100mm slump for our concrete as per specification. so we need to increase the water content to the required slump . clause 4.2 of IS1026 suggests to increase 3% of water content to get an extra 25mm slump. hence we need to increase water content by 6% to get an additional 50mm slump for our concrete.
water content for 100mm slump =186+(0.06*186)=197.16L
since we are using superplasticizers water content can be reduced inorder to get strength in concrete . the amount of water content to be reduce depends on the type of superplasticizer.
percentage of reduction in water content = 20%
water content requirement after SP=198-(0.20*198)=157.73
adopted water content =160L
vi)calculation of cement and fly ash content :
adopted water cement ratio=0.45
total cementitious (cement+fly ash)requirement= water content /water cement ratio=160/0.45=355.55kg
since flyash is used the amount of cementitious content(cement+ flyash) shall be increase to get good workability and strength.the percentage of cementitious content to be increased depends upon the experience and reasearch.here we have increase the cementitious content by 10%.
final cementitious content =356*1.10=391.6kg
minimum cement content required for "severe" exposure = 340kg -table 5-IS456
adopted cementitious content=391.6kg>340kg
flyash content requirement =391.6*0.30( 30% replacement)
=117.48~118kg
cement content requirement = cementitious content -flyash =391.6-117.48=274.12
calculation of super [email protected] to the mass of cementitious content= 391.6*(0.6/100)= 2.35kg
vii)coarse aggregate and fine aggregate :
coarse aggregate ratio=0.62 - table 3-IS10262(for W/C=0.5)
coarse aggregate ratio for 0.45 w/c ratio=0.63 9adding 0.01for every decreases 0.05 and vice varsa)
final fine aggregate ratio =(1-0.63)=0.37
viii)mix calculations of M35 grade concrete:
a) volume of concrete = 1cu.m
b)total volume of cement = cement /(s.g *1000)=275/(3.15*1000)=0.087cu.m
c)total volume of fly ash =flyash/ (s.g*1000)= 118/(2.5*1000)=0.041cu.m
d)volume of water =water/(s.g*1000)=160/(1*1000)=0.016cu.m
e)volume of superplasicizers=superplasticizers / (s.g*1000)=2.35/(1.12*1000)=0.002cu.m
f)total aggregates required =a-(b+c+d+e)=1-(0.087+0.041+0.16+0.002)=0.71cu.m
g)coarse aggregate (c.a)=f*c.a ratio*s.g*1000= 0.71*0.63*2.74*1000=1225.6kg
I)fine aggregate (f.a)=f*f.a ratio *s.g*1000=0.71*0.37*2.74*1000=719.8kg
CEMENT FLYASH SAND AGGREGATE WATER AND SUPERPLASTICIZER NEEDED FOR M35 GRADE CONCRETE:
1. cement- 275kg
2. flyash -118kg
3. fine aggregate -720kg
4. coarse aggregate - 1226kg
5. water - 160L
6.PCE Based superplasticizer- 2L
to find the design mix ratio divide the calculated value of all materials by the weight of cement . there for mix ratio of M35 grade concrete by weight is=cment:flyash:F.A:C.A:water=1:0.4:2.6:4.46:0.58