Project on Concrete Mix Design for various grades of Concrete

AIM OF THE PROJECT: Illustrating the mix proportioning procedure for M35 grade concrete using fly ash is given in A-1 to A-9

INTRODUCTION:

A-1 STIPULATIONS FOR PROPORTIONING :

a) Grade designation                                                                                            :M35
b) Type of cement                                                                                                 :OPC 43 grade conforming to IS 269
c) Type of mineral admixture                                                                                :Fly ash conforming to IS 3812(PART1)
d) Maximum nominal size of aggregate                                                               :20mm
e) Minimum cement content and maximum water-cement ratio to be adopted :Severe(for reinforced concrete)
and/or Exposure conditions as per Table 3 and Table 5 of IS456
f) Workability                                                                                                         : 75mm(Slump) 
g) Method of concrete placing                                                                             :Pumping
h) Degree of supervision                                                                                       :Good
j) Type of aggregate                                                                                               :Crushed angular aggregate
k) Maximum cement content (OPC content)                                                         :As per IS 456
m) Chemical admixture type                                                                                  :Superplasticizer-normal

A-2 TEST DATA FOR MATERIALS :

a) Cement used                                                                                                      :OPC 43 grade conforming to IS 269
b) Specific gravity of cement                                                                                  :3.15
c) Fly ash                                                                                                                 :Conforming to IS 3812(PART 1)
d)Specific gravity of fly ash                                                                                     : 2.2                                              
e)Chemical admixture                                                                                             :Superplasticizer conforming to IS 9103
f) Specific gravity of                                                                                                                                              
1)Coarse aggregate(at SSD condition)                                                                   :2.74
2)Fine aggregate(at SSD condition)                                                                        :2.65
3)Chemical admixture                                                                                             :1.145
g) Water absorption                                                                                                 
1) Coarse aggregate                                                                                                :0.5 Percent
2) Fine aggregate                                                                                                     :1.0 Percent
h)Free surface moisture                                                                                              
1)Coarse aggregate                                                                                                  :Nil
2)Fine aggrgate                                                                                                        :Nil
k)Sieve analysis
Fine aggregate                                                                                                          :Conformingto grading zone I of Table 9 of IS 383

A-3 TARGET STRENGTH FOR MIX PROPORTIONING:

 f'ck=fck+1.65 S
f'ck=target average compressive strength at 28days,
fck=characteristic compressive strength at 28days
S=standard deviation
From Table2, standard deviation,S=5N/mm^2
     f'ck=fck+1.65 S
           =35+1.65X5 =43.25N/mm^2

A-4 SELECTION OF WATER CEMENT RATIO :

Water cement ratio required for the target strength of 43.25 N/mm^2 is 0.37 for OPC 43 grade curve This is lowerthan the maximum value of 0.45 prescribed for severe exposure for reinforced concrete as per Table 5 of IS 456.

A-5 SELECTION OF WATER CONTENT :

From Table 4, water content =186 kg (for 50mm slump) for 20mm aggregate.
Estimated water content for 75mm slump (increasing at the rate of 3 percent for every 25mm slump)
                                                =186+3/100x186
                                                =191.58 kg
As superplasticizer is used,the water content may be reduced.The water content reduction of 30 percent is considered while using supeerplasticizer at the rate1.0 percent by weight of cement.
Hence the arrived water content=191.58x0.70=135 kg.

A-6 CALCULATION OF CEMENT CONTENT :

Water cement ratio=0.37
cement content =135/0.37 =365 kg/m^3
From Table 5 of IS 456  minimum cement for severe exposure condition = 320 kg/m^3
   365 kg/m^3 >320 kg/m^3 , hence ok
To proportion a mix containing fly ash
percentage of fly ash=30% ,with increase of 10 percent cementitious material content
Cementitious material content =365x1.10 =402 kg/m^3
Water content =135kg/m^3
So, water-cementitious ratio =135/402 =0.33
Fly ash @ 30percent of total cementitious material content=402x30% =120 kg/m^3
Cement (OPC)=402-120 =282 kg/m^3
Saving of cement while using fly ash =365-282 =83 kg/m^3 and
Fly ash being utilized =120 kg/m^3

A-7 PROPORTIONING OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT :

From Table 5, volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate(zone I) 
For water-cement ratio of 0.50 is 0.60.
In the present water cementitious ratio is 0.33
Therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content.
The volume of coarse aggregate increased by 0.0152.  Therefore, corrected proportion of volume of coarse aggregate for water-cementitious ratio of 0.33=0.60+0.032 =0.632
FOR pumpable concrete these values may be reduced by upto 10 percent.Therefore,volume of coarse aggregate =0.632x0.9 =0.56m^3
Volume of fine aggregate content=1-0.56 =0.44m^3

A-8 MIX CALCULATIONS :

The mix calculations per unit volume of concrete shall be as follows:
a) Total volume =1m^3
b) volume of cement =Mass of cement/specific gravity of cement x 1/1000
                                  =282/3.15 x 1/1000 =0.08m^3
c) volume of water = Mass of water/specific gravity of water x 1/1000
                              =135/1 x 1/1000 =0.135m^3
d) volume of fly ash = Mass of fly ash/specific gravity of fly ash x 1/1000
                                =120/2.2 x 1/1000 =0.05m^3
e) volume of chemical admixture=Mass of chemical admixture/specific gravity of admixture x 1/1000
                                                    =4.02/1.145 X 1/1000 =0.004m^3
f) volume of all in aggregate =(a-(b+c+d+e))
                                               =(1-(0.08+0.135+0.05+0.004)) =0.73m^3
g) mass of coarse aggregate =f x volume of coarse aggregate x specific gravity of fine aggregate x 1000
                                              =0.73 x 0.56 x 2.74 x 1000 =1120 kg/m^3
h) mass of fine aggregate =f x volume of fine aggregate x specific gravity of fine aggregate x 1000
                                          =0.73 x 0.44 x 2.65 x 1000 =851 kg/m^3
 
A-9 MIX PROPORTIONS :

Cement             = 282 kg/m^3
Fly ash               =120 kg/m^3
Water                 =135 kg/m^3
Fine aggregate   =851 kg/m^3
Coarse aggregate=1120 kg/m^3
Chemcial admixture=4.02 kg/m^3
Water cement ratio =0.33

TRIAL MIX RATIO =1: 2.11 : 2.78

2) AIM OF THE PROJECT :Ilustrating the mix proportion for a concrete of M50 grade is given in B-1 to B-9

INTRODUCTION :

B-1 STIPULATIONS FOR PROPORTIONING :

a) Grade designation                                                                                        : M40
b) Type of cement                                                                                             : OPC 53 grade conforming to IS 269
c) Maximum nominal size of aggregate                                                           : 20mm
d) Minimum cement content and
 maximum water-cement ratio to be adopted and/or
Exposure condition as per Table 3 and Table 5
of IS 456                                                                                                             : Severe (for reinforced concrete)
e) Workability                                                                                                       : 100 mm (slump)
f) Method of concrete placing                                                                            : Pumping
g) Degree of supervision                                                                                      : Good
h) Type of aggregate                                                                                             : Crushed stone angular aggregate
i) Maximum cement (OPC content)                                                                     : As per IS 456 
j) Chemical admixture type                                                                                 : Super plasticizer- normal

B-2 TEST DATA FOR MATERIALS :
                
a) Cement used                                                                                                      : OPC 53 grade conforming to IS 269
b) Specific gravity of cement                                                                                  : 3.15
c) Chemical admixture                                                                                            : Super plasticizer conforming to IS 9103
d) Specific gravity (at SSD condition) of
1) Coarse aggregate                                                                                                : 2.74 
2) Fine aggregate                                                                                                     : 2.65 
3) Chemical Admixture                                                                                             : 1.145
e) Water absorption
1) Coarse aggregate                                                                                                 : 0.5 percent
2) Fine aggregate                                                                                                      : 1.0 percent
f) Moisture content of aggregate [As per
IS 2386(Part 3)]
1) Coarse aggregate                                                                                                    : Nil
2) Fine aggregate                                                                                                         : Nil
h)sieve analysis
1)Fine aggregate                                                                                                           :Conforming to grading zone I of Table 9 of IS 383

B-3 TARGET STRENGTH FOR MIX PROPORTIONING :

  f'ck=fck+1.65 S
Where
f'ck=target average compressive strength at 28 days
fck=charcteristic compressive strength at 28 days
S= standard deviation
   f'ck=50+1.65x5
   f'ck=58.25N/mm^2

B-4 SELECTION OF WATER-CEMENT RATIO :

 Water cement ratio required for 58.25 N/mm^2 is 0.33 for OPC 53 grade

B-5 SELECTION OF WATER CONTENT :

From Table 4, water content=186 kg (for 50mm slump) for 20mm aggregate
Water content for 100mm slump=186+6/100x186
                                                     =197.16 kg
As super plasticizer is used , the water content may be reduced,the water reduction of 30 percent is considered while using superplasticizer 
at the rate 1.0 percent by weight of cement
Hence the water content =197.16x0.70 =140 kg

B-6 CALCULATION OF CEMENT CONTENT :

Water cement ratio =0.33
Cement content =140/0.33 =425 kg/m^3
Fron Table 5 of IS 456, minimum cement content for severe exposure condition =320 kg/m^3
 425 kg/m^3 > 320 kg/m^3 , hence OK

B-7 PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT :

 From Table 5, the volume of coarse aggregate corresponding to 20mm size aggregate(zone I) for water cement ratio of 0.50=0.60
 In the present Water cement ratio is 0.33.
Therefore volume of coarse aggregate is to be increased to decrease fine aggregate content.
Corrected proportion of volume aggregate for water cement ratio of 0.33=0.60+0.032 =0.632
For pumpable concrete these values reduced upto 10 percent,
Volume of coarse aggregate =0.632x0.9 =0.56m^3
volume of fine aggregate =1-0.56 =0.44m^3

B-8 MIX CALCULATIONS :

The mix calculations per unit volume of concrete shall be as follows:
a) Total volume = 1m^3
b) Volume of cement = mass of cement/specific gravity of cement x 1/1000
                                  = 425/3.15 x 1/1000 = 0.13 kg/m^3
c) Volume of water = mass of water/specific gravity of water x 1/1000
                               = 140/1 x 1/1000 = 0.14 m^3
d) Volume of chemical admixture = mass of chemical admixture/specific gravity of admixture x 1/1000
                                                      = 4.25/1.145 x 1/1000 = 0.0037 m^3
e) Volume of all in aggregate = (a-(b+c+d))
                                                =(1-(0.13+0.14+0.0037))
                                                =0.72 m^3
f) Mass of coarse aggregate = e x volume of coarse aggregate x specific gravity of coarse aggregate x 1000
                                              =0.72 x 0.56 x 2.74 x 1000 =1104 kg
g) Mass of fine aggregate = e x volume of fine aggregate x specific gravity of fine aggregate x 1000
                                           =0.72 x 0.44 x 2.65 x 1000 =840 kg

B-9 MIX PROPORTIONS :
Cement        = 425 kg/m^3
Water           =140 kg/m^3
Fine aggregate = 840 kg/m^3
Coarse aggregate = 1104 kg/m^3
Chemical admixture = 4.25 kg/m^3
Water-cement ratio = 0.33

TRIAL MIX RATIO = 1 : 1.97 : 2.59