Sunday, November 27, 2016

40 MPA CONCRETE MIX DESIGN ACI 211


Example according to ACI  211


Strength = 40 MPa
Cement = OPC ( Ordinary Portland Cement)
Fine Aggregate = Natural Sand and Crush sand
Fine Aggregate fine Modulus = 2.7 23
FA Specific Gravity  = 2.602
FA absorption = 2.60

(CA)Coarse Aggregate NMS = 19 mm
CA Specific Gravity =  2.619
Absorption = 1.123
Dry density = 1510 kg/m3
Step No 1
Selection of Slump and compressive Strength
Slump = 80 mm
Compressive strength
There is no available data for s so we use this equation
Fcr = Fc + 10 MPa
Fcr = 40+10
Fcr= 50 MPa
Step 2
Selection of Coarse aggregate proportion
NMS = 19 mm
So from table 8 when Nominal Max size is 19 then CA Volume = 0.64

Weight of Coarse Aggregate = 0.64*1510 =  966.4

Step 3
Calculation of water Cement and Air Content

From  table 2 & 3 when NMS =19mm then

Water = 205 Kg

Air content = 2%

Selection of w/c ratio

From table 6 when compressive strength = 40 MPa

Then w/c = 0.40
Step 6
Calculation of Cement Content
Here we are using 2 percent super plasticize which reduces water content
Up to 20%
205*80% =  164
Weight of Cement = 164/0.41   = 410 kg/m3


Step No 7
Calculation of  Volume of All mix Ratios


Volume of cement = Wt of Cement/ Specific gravity (C/γc)
                                =410/3.15*1000                       =  0.1301

Volume of  Water =  Mixing water / Sp g * 1000
                                = 164/1*1000                =0.164
                                                                                    

Absolute Vol of Coarse Aggregate = 966.4/2.619*1000
                                                                                  = 0.368899

Volume of Air = 2/ 10000                                          =0.002
                                                                                     
Total Absolute volume                                              =0.66499

Wt of Fine Aggregate
                     =1- Summation of Volume of Cement, Water                                                                    Coarse aggregate

                     =1 – 0.66499
                     =0.33501



Wt of Fine Aggregate = Volume of Fine aggregate * Sp gravity*1000
                                      = 0.33501*2.602*1000
                                     = 871 kg

Trail Batch
So Finally we will get these weight for trail either in laboratory or batching Plant



Cement                  = 410 Kg
Water                     =164 kg
Coarse Aggregate  =966.4 kg

Fine Aggregate      =871 kg

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