Project on Concrete Mix Design for various grades of Concrete
1.Stipulations of proportioning
a) Grade-M35
b)Type of Cement- OPC 43 Grade conforming of IS 8112
c)Type of admixture- fly ash conforming of IS3812(part-1)
d)Maximum size of aggregates - 20mm
e)min cement content-320kg/m^3( from table 5 IS456:2000-exposure condition)
f) Max water-cement ratio : 0.45 ( from table 5 IS456:2000-exposure condition)
g) Workablilty-100mm
h) Exposure condition- Server
i)Max cement content-450kg/m^3
j) chemical admixture type-superplasticizers
TEST DATA FOR MATERIALS:
a) Cement used-OPC 43 Grade conforming of IS 8112
b) specific gravity of cement-3.15
c) fly ash- conforming of IS 3812(part-1)
d) specific gravity of fly ash-2.2
e) Chemical admixture - superplasticizer conforming of IS 9103
f) specific gravity of coarse aggregate-2.74
specific gravity of fine aggregate-2.74
g) water absorption of coarse aggregate-0.5%
water absorption of Fine aggregate-1%
Target strenght of MIX proportioning:
1)F'ck= Fck +1.65s
from table 1 IS 10262:2009 , standard devation s=5n/mm^2
therefore strength = 35+1.65*5
= 43.25N/mm^2
2)Selection of water-cement ratio
from table 5 IS 456:2000 for server exposure- 0.45
3)selection of water cement form table 2 IS 10262:2009, Maximum water content for 20mm aggregate=186litres(for 20 to 50mm slump value)
estimate water content for 100mm slump- 186+6/100*186
=197
as superplasticizer is used , water content can be reduced upto 30%
based on trail water content reduction of 29% is achieved with Plasticizer
hence the arrived water content-197*0.71=140litre
4)calculation of cement content
water-cement ratio=0.4
cementation content(cement+fly ash)-140/0.4=350kg/m^3
from the table 5 of IS456 minimum cement content for'server'exposure condition=320kg/m^3
350kg/m^3 >320kg/m^3, hence it is ok
a) percentage of fly ash requirement need is decided on the project requirement and quality of material
b)In some case increase in cementitious material can be warrented.increase in cementitious material content and its percentage may be based on experience and trails(this example increase of 10% cementitious material content)
cementitious material content =350*1.10=385kg/m^3
water content =140kg/m^3
so, water-cement ratio= 140/385=0.364
fly ash @ 30% total cementitious material content=385*30%=115kg/m^3
cement(opc)= 385-115=270kg/m^3
fly ash being utilized = 115kg/m^3
5)Proporation of volume of coarse aggregate and fine aggregates content;
from table 3 of IS 10262:2009, volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate(zone 1) for water- cement ratio of 0.5=0.6
In present case water cement ratio is 0.4
- Therefore, the volume coarse aggregate need to be increased to decrease the fine aggregate content.
- as water-cement ratio is lower by 0.10,the proportion of volume of coarse aggregate is increased by 0.02
(at rate of -/+0.01 for every +-0.05 change in water-cement ratio)
Therefore corrected volume of coarse aggregate for water-cement ratio of 0.40=0.62
for pumpable concrete these value is reduced by 10%
Therefore, volumne of coarse aggregate=0.62*0.9=0.56
volumne of coarse aggregate=1-0.56
=0.44
6) MIX calculations
- Volume of concrete=1m^3
- Volume of cement= mass of cement/specific gravity of cement*1/1000
270/3.15*1/1000=0.086m^3
- Volume of Fly Ash= mass of fly ash/specific gravity of fly ash*1/1000
115/2.2*1/1000=0.052m^3
- Volume of water= mass of water/specific gravity of water*1/1000
=140/1*1/1000=0.140m^3
- Volume of admixture= mass of admixture/ specific gravity of admixture*1/1000
=7.6/1.145*1/1000=0.006m^3
- Volume of aggregate(FA & CA) =a-(b+c+d+e)
=1-(0.086+0.052+0.140+0.006)
=0.716m^3
- Mass of coarse aggregate= f*volume of CA * specific gravity of CA * 1000
=0.716*0.56*2.74*1000=1098kg/m^3
- Mass of Fine aggregate= e*volume of FA * specific gravity of CA * 1000
=0.716*0.44*2.74*1000=863kg/m^3
trial mix ratio=1:2.24:2.85