Issue 50

K. Kaklis et alii, Frattura ed Integrità Strutturale, 50 (2019) 395-406; DOI: 10.3221/IGF-ESIS.50.33

Deformation characteristics One uniaxial compression test and four triaxial compression tests under cyclic loading conditions were performed in order to examine the deformation characteristics of the pozzolanic lime mortar. By processing the experimental data the plastic strain, the total strain as well as the Young’s modulus of the material were determined and presented in Table 1, for each one of the five loops. Note that in the loops performed at relatively low stress levels of the triaxial cyclic compression test with lateral pressures of 2.09 MPa and 3.96 MPa, the calculated values of the Young’s modulus did not range within the acceptable limits for this material and were excluded from Table 1. In addition, these values are not taken into account in the subsequent calculations and they do not appear in the respective diagrams.

Uniaxial

Triaxial confining pressure of 1.15 MPa

Deviator stress (MPa)

Plastic strain, ε pl (x10 -3 )

Total strain, ε (x10 -3 )

Young’s modulus, Ε(MPa)

Deviator stress (MPa)

Plastic strain, ε pl (x10 -3 )

Total strain, ε (x10 -3 )

Young’s modulus, Ε(MPa)

Loops

1 st

1.85 2.98 4.67 5.78 7.04

0.447 0.552 0.845 1.319 2.244

0.672 0.967 1.591 2.314 3.525

7720 6720 6228 5972 5537

3.50 4.64 6.40 8.13

0.203 0.332 0.512 1.150

0.466 0.702 1.181 2.113

14105 12328

2 nd 3 rd 4 th 5 th

9426 8374

-

-

-

-

Triaxial confining pressure of 2.09 MPa

Triaxial confining pressure of 3.96 MPa

Deviator stress (MPa)

Plastic strain, ε pl (x10 -3 )

Total strain, ε (x10 -3 )

Young’s modulus, Ε (MPa)

Deviator stress (MPa)

Plastic strain, ε pl (x10 -3 )

Total strain, ε (x10 -3 )

Young’s modulus, Ε (MPa)

Loops

1 st

3.09 4.14 5.35 6.36 7.87

0.912 1.257 1.960 3.164 6.594

0.946 1.545 2.549 3.957 7.665

- -

2.26 3.12 4.71 6.20 7.78

1.041 1.313 1.931 3.463 6.881

1.041 1.380 2.315 4.073 7.707

- -

2 nd 3 rd 4 th 5 th

9256 8391 7705

12343 10091

9531

Triaxial confining pressure of 6.06 MPa Deviator stress (MPa) Plastic strain, ε pl (x10 -3 ) Total strain, ε (x10 -3 ) Young’s modulus, Ε(MPa)

Loops

1 st

3.36 5.19 6.25 7.31 8.94

1.466 1.929 3.349 5.924

1.466 2.216 3.810 6.560

-

18170 13663 11601

2 nd 3 rd 4 th 5 th

10.458 11.358 Table 1 : Results of uniaxial and triaxial compressive tests under cyclic loading. 11.247

Fig.4a and Fig.4b show the relationship between the plastic strain and the elastic strain, respectively, as a function of the total strain of the mortar specimens subjected to both uniaxial and triaxial compressive cyclic loading for each of the five unloading-reloading loops. These diagrams show clearly the different behavior of the mortar specimens tested in uniaxial and triaxial cyclic loading. From a regression analysis, linear relationships between the plastic strain and total strain, as well as the elastic strain and total strain are derived, with a correlation coefficient higher than 0.95, both in uniaxial (1) and triaxial (2) compressive cyclic loading scenarios. It should be noted that the fitting of results for the triaxial cyclic compression tests took into account the data points from all three different confining pressures.

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