Project on Concrete Mix Design for various grades of Concrete
we need to assume some quantitied to design of m35 grade concrete.
grade designation=m35
type of cement=OPC 43grade
size of aggregate=20mm
min cement content=320 kg/m3 (is 456:2000)
max water cement ratio =0.45
workability =100mm of slumo value
exposure=severe
method of placing=pumping
degree of super vision=good
type of aggregate=crushed angular aaggregate
max cemnt content=450kg/m3
chemical admixture=super plasticizer
mineral admixture=flyash
specific gravity of cement=3.15
s.g of fly ash=2.2
s.g of coarse aggregate=2.74
s.g of fine aggregate=2.75
water absorption of coarse aggregate=0.5%
w.a of fine aggregate=1%
target strength ft=fc+1.65s
we can get the s value from the is456:2000 table no 6
for m35 the s value is 5
so,35+1.65(5)=43.25
from the given water/cement ratio we can reduce it to 0.4 based on the experience
now we calculate the water quantiy from the is10262:2009 table 2
for 20mm aggregate we need to use186 lit
for every rise of 25mm from 50mm we need to increase the 3% of water .so for 100mm we need to increase the 6% of water as extra
so,186*6%+6%=197 li
we are using super plasticezer we can reduce the water quantity upto 30%
197*30%-197=137.9=140 lit
by this we can calculate the cement content=w/c=0.4
140/0.4=350 kg(it is more than the min content. and also itts less than the max content)
we are using fly ash so we want to incerase the quantity into 10%
so 350*10%+350=385 kg/m3
now water /cement ratio is =140/385=0.364
fly is added upto 30% of cementious material=385*30%=115 kg/m3
now final cement quantity is =385-115=270 kg/m3
saving of cement=350-270=80kg/m3
already we reduced the w/c ratio 0.6 (from the graph)so,we need to increase for +/- of 0.05 in water /cement ratio +/- invol of c.a of 0.01
from table 3 we can calculate the volume of c.a/f.a=0.6
so its increased to 0.62.
if its is pumpable concrete we need to decrease the volume to 10% =0.62*0.9=0.56
volume of fine aggreagte=1-0.56=0.44
mix calculation
a)volume of concrete=1m3
b)volume of cement =mass of cement/s.g of cement *1/1000=270/3.15*1/100=0.08
c)volume of water=140/1*1/1000=0.14m3
d)volume of chemical admixtutre=7.6/1.145*1/1000=0.006m3
(mass of chemical admixture =2% mass of cementious material is added)
e)volume of fly ash=115/2.2*1/1000=0.02
f)now volume of c.a and f.a=(a-(b+c+d+e)
=(1-(0.086+0.052+0.14+0.666))=0.716
mass of c.a=f*vol.of c.a8s.g*1000=0.716*0.5*2.74*1000=1098kg/m3
mass of fine aggregate=0.716*0.44*2.74*1000=863 kg/m3
for m50 grade concrete
grade designation =m50
type of cement=OPC53
maximum nominal sixe of aggregate=20mm
minimum cement content=360kg/m3
max water cement/ratio=0.35
workability=75 mm slumo
exposure cindition=extreme
method concrete placing=pumping
degree of super vision=good
type of aggregate=crushed angular aggregate
maximum cement content=450kg/m3
chemical admixture=super plasticizer
s.g of cement=3.12
s.g of c.a=2.74
s.g of f.a=2.56
target strength=fck+1.65s
from 10262table no1
s=5
ft=50+1.65*5=58.25
selection of w/c ratio=0.35
selection of water content from is 456:2000
table2 for 20mm aggregate for 25-50mm slump 186 lit
for every rise in 25 mm of slump we need to increase the 3% of water content for 100mm we need to increase the water content to 3%+3%
186+186*6%=197
we are using super plasticizer we can reduce the water content to 20%=197*27%-197=143 lit
calculation if cement content=0.35
cement content =143/0.3=410 kg/m3
its is greater than 360 kg/m3
proportion of volume of coarse aggregate and fine aggregate
from table 3 is 456:2000 we choose 20mm as aggregate size of zone 2 for a water cement ratio of 0.5 =0.62
swe decreased the w/c ratio so we need to incerese the aggregate value of evry+/- 0.05 we need to increase the c.a to+/-0.01
so we needed tpo increase the 0.62 to 0.65
the concrete is placed through pumpable concrete,so we need to reduce 10% so 0.62*0.9=0.585
volume of f.a =1-0.585=0.415
mix calculations
a)volume of concrete=1m3
b)volume of cement=mass of cement/s.g of cement *1/1000=410/3.12 *1/1000=0.143m3
c)volume if water=143/1 *1/1000=0.143m3
d)volume of super plasticizer =8.2/1.45 *1/1000=0.007m3
e)volume of aggeregate=1-(0.131+0.143+0.007)=0.719m3
f)mass of coarse aggregate=volume of aggregate *volume of c.a*s.g of c.a*1000
=0.719*0.585*2.74*1000
=1152 kg/m3
g)mass of f.a=0.719*0.415*2.56*1000=763.86 kg/m3
concrete mix proportions=
cement=410 kg/m3
water =143kg/m3
super plasticizer=7kg/m3
fine aggregate=763.86kg/m3
coarse aggregate=1152.48 kg/m3
w/c=0.35