MIX
DESIGN OF M-20 CONCRETE
A.DESIGN STIPULATIONS
1.Grade designation Grade
M = 20
2.Maximum N/size of aggregate =
20 mm
3.Type of Aggregate = Crushed angular aggregate
4.Type of
Cement OPC 43 Grade confirming to IS-8112
5.Maximum Cement Content = 450kg/m3
6.Minimum Cement Content = 300 kg/m3
7.Maximum
Water-Cement ratio =
.55
8.Workability
slump = 30mm
9.Degree
of Supervision
= Good
10.Chemical
admixture type = Nill
11.Exposure
Condition = Mild
12.Method
of concrete placing = Manual
B.TEST DATA FOR MATERIALS
Specific gravity
1.Cement
= 3.150
2.Coarse Aggregate = 2.670
3.Fine aggregate = 2.640
4.Plasticizer
= NA
5.Water
= 1.000
Water absorption
1.Coarse Aggregate
= 0.88%
2.Fine Aggregate = 0.50%
Free Surface moisture
1.Coarse Aggregate = 0.000
2.Fine Aggregate = 0.00
Sieve analysis
1.Coarse Aggregate
Table:-Grading of
Coarse Aggregate for mix design
|
Total aggregate
|
Coarse aggregate
|
|||
|
20.0
|
12.5+lower
|
|
|
|
|
% blend
|
60.00
|
40.00
|
|
|
|
IS Sieve
|
% of passing specified
|
Achieved
|
||
|
|
LOWER
|
UPPER
|
MID
|
|
|
40.00
|
100
|
100
|
100
|
100
|
|
20.00
|
95.00
|
100.00
|
97.50
|
98.60
|
|
4.75
|
0.00
|
10.00
|
5.00
|
4.33
|
2.Fine aggregate
Table:-Grading of Fine
Aggregate for mix design
|
IS Sieve
|
% of passing specified
|
Achived
|
||
|
|
Lower
|
Upper
|
Mid
|
|
|
10 mm
|
100.00
|
100.00
|
100.00
|
99.89
|
|
4.75 mm
|
90.00
|
100
|
95
|
95.04
|
|
2.36 mm
|
75
|
100.00
|
87.50
|
86.81
|
|
1.18 mm
|
55
|
90.00
|
72.5
|
65.07
|
|
600µ
|
35.00
|
59.00
|
47.00
|
43.87
|
|
300µ
|
8
|
30.00
|
19.00
|
12.37
|
|
150µ
|
0.00
|
10.00
|
5.00
|
2.67
|
Qualified Zone = 2
C.DESIGN COMPRESSIVE
STRENGTH FOR MIX
f'ck = fck +
1.65*s
where
f'ck =
target mean compressive strength at 28 days
fck = characteristic
compressive at 28 days
s = Standard deviation
= 4.00
f'ck = 26.6 N/mm2
D.SELECTION OF
WATER-CEMENT RATIO
Permissible
Max. W-C Ratio = 0.55
W-C Ratio =
0.55 hence Ok
ADOPT W-C ratio =
0.50
E.SELECTION OF WATER
CONTENT
Approximate water content / Cum without
Plasticizer = 186.00 kg
Correction for slump = 0.00 kg
Correction for shape & type of aggregate =
0.00 kg
Net. Max. water content= 186.00 kg
Net. Arrived water content.= 186.00 kg
F.CALCULATION OF CEMENT CONTENT
Adopted W-c
Ratio = 0.50
Net. Arrived water content = 186.00 kg
Cement content =372.00 kg
Minimum cement content as per IS 456-2000 = 300.00
kg
maximum cement content as per IS 456-2000 = 450.00
kg
Hence ok
Adopt Cement Content = 372.00 kg
G.CALCULATION OF VCA, VFA
volume of ca/ total Agg volume for w-c ratio =
0.50 =62.00%
correction factor =0.00%
net. volume of ca / total agg volume for w-c ratio
0.5 =62.00%
correction for shape & type of aggregate =0.00%
Correction for method of placing =0.00%
adopt net. volume of ca/ total agg. volume =62.00%
volume of ca Vca =62.00%
volume of fa Vfa = 38.00%
Fig:-Showing Concrete Mix
H.MIX CALCULATION
total volume of concrete =1.000 m3
volume of cement =0.118 m3
volume of water =0.186 m3
volume of chemical admixture =0 .000 m3
volume of all-in aggregate Vta =0.696 m3
mass of ca Mca =1153.00 Kg
mass of fa Mfa =699.000 Kg
I.MIX PROPORTION
Trial No. 1 for for
desired workability as slump =30mm
quantities of various
constituents
cement =
372.00 kg/m3
water = 186.00 kg/m3
chemical admixture = 0.00 kg/m3
w/c ratio = 0.50
fine aggregate = 699.00 kg/m3
coarse aggregate= 1153.00 kg/m3
Quantities of various
constituents after moisture correction
cement = 372.00 kg/m3
water = 199.64 kg/m3
chemical admixture =0.00 kg/m3
w/c ratio =0.54
fine aggregate = 695.51 kg/m3 37.83%
coarse aggregate=1142.85 kg/m3 62.17%
CA 20mm = 685.71
kg/m3
CA 12.5mm = 457.14 kg/m3
CA <12.5mm = 0.00
kg/m3
For Design
mix
Grade M = 20
with provision of chemical admixture =
0.00% by mass of cement
Table:-Proportion of various constituents
|
Cement
|
FA
|
CA-1
|
CA-2
|
CA-3
|
CA = 1+2+3
|
Water
|
|
|
|
20
mm
|
10
mm
|
|
Total
|
|
|
Kg
|
Kg
|
Kg
|
Kg
|
Kg
|
Kg
|
Kg
|
|
372.00
|
695.51
|
685.71
|
457.14
|
0.00
|
1142.85
|
199.64
|
|
|
37.83%
|
|
|
|
62.17%
|
0.54
|
|
1.00
|
1.87
|
1.84
|
1.23
|
0.00
|
3.07
|
0.54
|
Table-Compressive strength of concrete block
|
Trial
|
W.C.Ratio
|
Comp. st.
of trial mix
|
Desired comp. st.
|
Slump value for trial mix
|
Plasticizer content
|
Remark s
|
||
|
At
7 days
|
At
28 days
|
At
7 days
|
At
28 days
|
|||||
|
Nos.
|
|
N/mm2
|
N/mm2
|
N/mm2
|
N/mm2
|
Mm
|
%
|
-
|
|
01
|
0.53
|
22.97
|
|
19.75
|
26.6
|
30
|
0
|
|
|
02
|
0.54
|
22.59
|
|
19.75
|
26.6
|
30
|
0
|
|
|
03
|
0.55
|
21.93
|
|
19.75
|
26.6
|
30
|
0
|
|
RESULT
as per above results, desired strength of cement
concrete m-20 grade cubed mould of 7 days have been achieved as 22.59 N/mm2.
Therefore , above rcc mix design may be adopted as provisional design mix
design for above mentioned rcc work tilll28 day's compressive strength is
checked.
There fore as per above trial results, results of
sample 2 has been consider as optimum and suitable.
PRECAUTIONS
§ Safety shoes should be used at the time of testing.
§ Before testing, CTM machine should be properly checked
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