Project on Concrete Mix Design for various grades of Concrete
To Calculate the concrete mix design for M35 Grade concrete with Fly ash
Step 1
Grade designation : M35
Type of Cement : OPC M43 Grade conforming to IS 8112
Type of mineral admixture : Fly ash conforming to IS 3812 (Part 1)
Maximum nominal size of aggregate : 20MM
Maninimum cement content : 320 kg/ m^3 ( Table 5 IS 456:2000 Exposure condition)
Maximum water - cement : 0.45 (Table 5 of IS 456:2000 Exposure condition)
Workability : 100MM (Slump value for pumpable concrete )
Exposure condition : Severe ( For reinforced concrete )
Method of concrete placing : Pumping
Degree of Supervision : Good
Type of aggregate : Crushed angular aggregates
Maximum cement content : 450kg/m^3
Chemical admixture type : Super plasticizer
Step 2
Test Data for materials
Cement used : OPC 43 Grade conforming IS 8112
Specific gravity cement : 3.15
Fly ash : Conforming to IS 3812 (part 1)
Specific gravity to Fly ash : 2.2
Chemical admixture : Super plasticizer conforming to IS 9103
Sepcific gravity of coarse aggregate : 2.74
Sepcific gravity of fine aggregate : 2.74
Water absorption of coarse aggregate : 1.0%
Free surface moisture of coarse aggregate : Nill
Free surface moisture of fine aggregate : Nill
Sieven analysis : Coarse aggregate conforming to table 2 of IS 383
Sieven analysis : Fine aggregate to grading Zone 1 of table of IS 383
Step 3
Target strength for mix proportioning
F'Ck = FCK + 1.65 X S
F'CK = Target compressive strength of 28 days
FCK = Characteristics compressive strength at 28 days
S = Standard deviation
From table 1 of IS 10262 : 2009 standard deviations S = 5N/MM^2
= 35 +1.65 X 5
= 43.25 N/MM^2
Step 4
Selection of water - cemet ratio
The maximum water cement ratio to design
M50 Grade concrete can maximum Water cement ratio be found
From Table 5 of IS = 0.45 456 : 2000 for sever exposure
Based on Experience adopted water cement ratio is 0.40
0.40 < 0.45 Hence ok
Step 5
Selection of water content
From Table 2 of IS 10262 : 2000 maximum
186 litre ( For 25 to 50mm slump range )
Estimated water content for 100mm slump = 186 + 6/100 X 186
= 197 liter
As superplastizer is used the water content can be reduced up to 20% and above
Based on trails water content reduction of 29% is achevied with plasticizer
Hence the arrived water content = 197 X 0.71
= 140 liter
Step 6
Calculation of cement content
Water cement ratio = 0.40
Cementitious material (cement + Fly ash) content = 140/ 0.4
=350 kg/m^3
Fromn table 5 IS 456 : 2000 minimum cement content for sever condition = 320kg/m^3
350kg/m^3 > 320kg/m^3 Hence ok
Now to Proportion a mix containing fly ash the foloowing steps suggested
a) The percentage of fly ash needs to be decided based on project requirement quality of materials
b) In some cases increase in cementitious materials can be warranted increase in cementitious materials
Content and its percentage may be based on experienced and trials
(This example is with increase of 10% cementitious materilas contenet)
Cementitious materila content = 350 X 1.10 = 385kg/m^3
Water content = 140 kg/m^3
So, water - cement ration = 140 / 385 = 0.364
Fly ash @ 30% total cementitious material = 385 X 30% = 115kg/M^3
Cement (OPC) = 385 - 115 = 270kg/m^3
Saving of cement whilw using fly ash = 350 - 270 = 80kg/m^3
Fly ash being utilized = 115kg/m^34
Step 7
Proportion of volume of coarse aggregate and fine aggregate 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 0.5 = 0.6
In the present case thye water cement ratio is 0.4
There fore the volume of coarse aggregate need to be increase to decrease the fine aggregate content
As water cement ratio is lower by 0.10 the proportion of volume of coarse aggregate is increase by 0.02 ( at the of -/+ 0.01 for every +- 0.5 change in water cement ratio)
There fore corrected proportion of volume of coarse aggregate for the water cement ratio of 0.40 = 0.62
(Note : If coarse aggregate is not of angular type aslo the volume of coarse aggregate may be required to be increase suitably based on experince)
For pumpable concrete these value should be reduced b y up to 10%
There fore volume of coarse aggregate 0.62 X 0.9 = 0.558
Volume of fine aggregate 1-0.558 = 0.442
Volume of fine aggregate and coarse aggregate is 0.442 and 0.558 respetively
Step 8
Mix Calculation
The mix calculation per unit volume of concrete shall be as follows
a) Volume of concrete = 1m^3
b) Volume of cement = Mass of cement / Specific gravity of cement X 1/1000
= 270 / 3.15 X 1 / 1000
= 0.086m^3
c) Volume of fly ash = Mass of fly ash / Specific gravity of fly ash X 1/1000
= 115 / 2.2 X 1 / 1000
= 0.052
d) Volume of water = Mass of water / Specific gravity water X 1/1000
= 140/1 X1/1000
= 0.140m^3
f) Volume of chemical admixture = Mass of admixture / Specific gravity admixtur X 1/1000
= 7.6/1.145 X 1/1000
= 0.006m^3
Volume of aggregate (FA & CA) = [ a(b+c+d)]
= [ 1 ( 0.086+0.0.052+0.140+ 0.006]
= 0.716m^3
g)Mass of coarse aggregate
= e X volume of coarse aggragate X specific gravity of coarse aggregate X 1000
= 0.716 X 0.558 X 2.74 X 1000
= 1095kg/m^3
h) Mass of fine aggregate
= e X volume of fine aggragate X specific gravity of fine aggregate X 1000
= 0.716 X 0.442 X 2.74 X 1000
= 867kg/m^3
Step 9
Mix proportions for Trial number 1
Cement = 270kg/m^3
Fly ash = 115kg/m^3
Water = 140kg/m^3
Fine aggregate = 867kg/m^3
Coarse aggregate = 1095kg/m^3
Chemical admixture = 7kg/m^3
Water - cement ration = 0.364
Trial Mix ration = 1 : 3.21 : 4.05
Step 10
The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving required slump on trial. the mix porportion shall be reworked for the actual water content and checked for durability requirement
Step 11
Two more trial having variation if 10% water - cement ratio in clause X shall be carried out and a graph between three water - cement ratios and corrsponding strength shall be plotted to work out the mix proportion for the given target strength for fileds. However , durability shall be be met.
To Calculate the concrete mix design for M50 Grade concrete without Fly ash
Step 1
Grade designation : M50
Type of Cement : OPC M53 Grade conforming to IS 8112
Maximum nominal size of aggregate : 20MM
Maninimum cement content : 320 kg/ m^3 ( Table 5 IS 456:2000 Exposure condition)
Maximum water - cement : 0.45 (Table 5 of IS 456:2000 Exposure condition)
Workability : 75MM (Slump value for pumpable concrete )
Exposure condition : Severe ( For reinforced concrete )
Method of concrete placing : Pumping
Degree of Supervision : Good
Type of aggregate : Crushed angular aggregates
Maximum cement content : 450kg/m^3
Chemical admixture type : Super plasticizer
Step 2
Test Data for materials
Cement used : OPC 53 Grade conforming IS 8112
Specific gravity cement : 3.15
Chemical admixture : Super plasticizer conforming to IS 9103
Sepcific gravity of coarse aggregate : 2.74
Sepcific gravity of fine aggregate : 2.74
Water absorption of coarse aggregate : 1.0%
Free surface moisture of coarse aggregate : Nill
Free surface moisture of fine aggregate : Nill
Sieven analysis : Coarse aggregate conforming to table 2 of IS 383
Sieven analysis : Fine aggregate to grading Zone 1 of table of IS 383
Step 3
Target strength for mix proportioning
F'Ck = FCK + 1.65 X S
F'CK = Target compressive strength of 28 days
FCK = Characteristics compressive strength at 28 days
S = Standard deviation
From table 1 of IS 10262 : 2009 standard deviations S = 5N/MM^2
= 50+1.65 X 5
= 58.25 N/MM^2
Step 4
Selection of water - cemet ratio
The maximum water cement ratio to design
M50 Grade concrete can maximum Water cement ratio be found
From Table 5 of IS = 0.45 456 : 2000 for sever exposure
Based on Experience adopted water cement ratio is 0.40
0.40 < 0.45 Hence ok
Step 5
Selection of water content
From Table 2 of IS 10262 : 2000 maximum
186 litre ( For 25 to 50mm slump range )
Estimated water content for 75mm slump = 186 + 3/100 X 186
= 192 liter
As superplastizer is used the water content can be reduced up to 20% and above
Based on trails water content reduction of 29% is achevied with plasticizer
Hence the arrived water content = 192 X 0.71
= 136 liter
Step 6
Calculation of cement content
Water cement ratio = 0.40
Cement content = 136/ 0.4
= 340kg/m^3
Fromn table 5 IS 456 : 2000 minimum cement content for sever condition = 320kg/m^3
340kg/m^3 > 320kg/m^3 Hence ok
Step 7
Proportion of volume of coarse aggregate and fine aggregate 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 = 0.6
In the present case thye water cement ratio is 0.4
There fore the volume of coarse aggregate need to be increase to decrease the fine aggregate content
As water cement ratio is lower by 0.10 the proportion of volume of coarse aggregate is increase by 0.02 ( at the of -/+ 0.01 for every +- 0.5 change in water cement ratio
There fore corrected proportion of volume of coarse aggregate for the water cement ratio of 0.40 = 0.62
For pumpable concrete these value should be reduced b y up to 10%
There fore volume of coarse aggregate 0.62 X 0.9 = 0.558
Volume of fine aggregate 1-0.558 = 0.442
Volume of fine aggregate and coarse aggregate is 0.442 and 0.558 respetively
Step 8
Mix Calculation
The mix calculation per unit volume of concrete shall be as follows
a) Volume of concrete = 1m^3
b) Volume of cement = Mass of cement / Specific gravity of cement X 1/1000
= 340 / 3.15 X 1 / 1000
= 0.107m^3
c) Volume of water = Mass of water / Specific gravity water X 1/1000
= 136/1 X1/1000
= 0.136m^3
d) Volume of chemical admixture = Mass of admixture / Specific gravity admixtur X 1/1000
= 7/1.145 X 1/1000
= 0.006m^3
Volume of aggregate (FA & CA) = [ a(b+c+d)]
= [ 1 ( 0.107+0.136+0.0060]
= 1.035m^3
Mass of coarse aggregate
= e X volume of coarse aggragate X specific gravity of coarse aggregate X 1000
= 1.035 X 0.558 X 2.74 X 1000
= 1582kg/m^3
Mass of fine aggregate
= e X volume of fine aggragate X specific gravity of fine aggregate X 1000
= 1.035 X 0.442 X 2.74 X 1000
= 1253kg/m^3
Step 9
Mix proportions for Trial number 1
Cement = 340kg/m^3
Water = 136kg/m^3
Fine aggregate = 1253kg/m^3
Coarse aggregate = 1582kg/m^3
Chemical admixture = 7kg/m^3
Water - cement ration = 0.4
Trial Mix ration = 1: 3.68 : 4.65
Step 10
The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving required slump on trial. the mix porportion shall be reworked for the actual water content and checked for durability requirement
Step 11
Two more trial having variation if 10% water - cement ratio in clause X shall be carried out and a graph between three water - cement ratios and corrsponding strength shall be plotted to work out the mix proportion for the given target strength for fileds. However , durability shall be be met.