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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 5
S. S. Araújo | G. N. Guimarães | A. L. B. Geyer
the modulus tests were 27.6 GPa e 27.5 GPa, respectively, and
the averages for the clip gages and the LVDTs were 26.3 GPa e
19.8 GPa respectively.
For 100mm x 200 mm specimens, modulus results (see Figure 6)
obtained using strain gages had averages of 24.6 GPa and 30.6
GPa and their respective coefficients of variation were 13.2% and
1.9% for concrete classes C30 and C60. Results obtained with
dial indicators had averages of 24.1 GPa and 31.6 GPa and their
respective coefficients of variation were 16.1% and 17.7% for con-
crete classes C30 and C60. Results obtained with clip gages had
averages of 22.0 GPa and 29.8 GPa and their respective coef-
ficients of variation were 4.0% and 2.5% for concrete classes C30
and C60. Results obtained with LVDTs had averages of 14.9 GPa
and 20.3 GPa and their respective coefficients of variation were
13.5% and 7.9% for concrete classes C30 and C60. For 100mm x
200 mm specimens, modulus results obtained from dial indicators
and LVDTs presented larger variability.
For 150mm x 300 mm specimens, modulus results (see Figure 6)
obtained using strain gages had averages of 26.6 GPa and 29.8
GPa and their respective coefficients of variation were 2.6% and
4.0% for concrete classes C30 and C60. Results obtained with dial
indicators had averages of 26.9 GPa and 27.9 GPa and their re-
spective coefficients of variation were 3.8% and 7.6% for concrete
classes C30 and C60. Results obtained with clip gages had aver-
ages of 23.5 GPa and 30.8 GPa and their respective coefficients
of variation were 4.1% and 1.5% for concrete classes C30 and
C60. Results obtained with LVDTs had averages of 20.6 GPa and
23.2 GPa and their respective coefficients of variation were 1.4%
Table 4 – Statistical analysis of test results – static modulus of elasticity
–
Dial Indicators
–
37
27.5
4.4
16.1
–
Electrical Surface Bonded Strain Gages
–
35
27.6
3.05
11.0
–
Externally Fixed Strain Gages
–
39
26.3
3.8
14.4
–
Linear Variation Displacement Transducer - LVDT
–
37
19.8
3.6
18.2
100X200
–
–
73
24.4
5.96
24.4
150X300
–
–
75
26.2
3.4
13.1
Dial Indicators
C30
10
24.1
3.9
16.1
Dial Indicators
C60
9
31.6
5.6
17.7
Electrical Surface Bonded Strain Gages
C30
10
24.6
3.2
13.2
Electrical Surface Bonded Strain Gages
C60
6
30.6
0.58
1.9
Externally Fixed Strain Gages
C30
10
22.0
0.88
4.0
Externally Fixed Strain Gages
C60
9
29.8
0.74
2.5
Linear Variation Displacement Transducer - LVDT
C30
9
14.9
2.004
13.5
Linear Variation Displacement Transducer - LVDT
C60
10
20.3
1.6
7.9
Dial Indicators
C30
9
26.9
1.02
3.8
Dial Indicators
C60
9
27.9
2.1
7.6
Electrical Surface Bonded Strain Gages
C30
9
26.6
0.69
2.6
Electrical Surface Bonded Strain Gages
C60
10
29.8
1.2
4.0
Externally Fixed Strain Gages
C30
10
23.5
0.96
4.1
Externally Fixed Strain Gages
C60
10
30.1
0.46
1.5
Linear Variation Displacement Transducer - LVDT
C30
8
20.6
0.29
1.4
Linear Variation Displacement Transducer - LVDT
C60
10
23.2
2.9
12.6
(%)
Static Modulus of Elasticity (GPa)
OBS.: - Concrete types: concrete class C30 for dimensions100 mm x 200 mm and 150 mm x 300 mm and concrete class C60 for
dimensions 100mm x 200mm and 150mm x 300mm.
– Twelve of the individual results were considered as spurious values.
Situation of Study
N° of
Specimen
Size
(mm)
Type of strain measurement device
Type of
Concrete
Average
(GPa)
Standard
Deviation
Coefficient
of Variation
(GPa)
100X200
150X300