PSI - Issue 26

P. Nomikos et al. / Procedia Structural Integrity 26 (2020) 285–292 Nomikos et al. / Structural Integrity Procedia 00 (2019) 000 – 000

289

5

BPMmicro-parameters

Numerical UCS test

UCS PFC ̅ ̅ ̅ ̅ ̅ , ̅ Bonds

Contacts

Schmidt hammer rebound hardness

μ

Strong band

UCS est E t,est

BPM

Weak band

R

T

E t,PFC

1

Strong band

Axial stress

P-wave velocity

Axial strain

(a)

(b)

Fig. 4. (a) Indirect estimation of the weak and strong band material properties. (b) Calibration of the BPMs.

Table 1. BPM micro-parameters for the weak and strong material bands (Nomikos et al., 2020). BPM micro-parameter Strong material band Weak material band Stiffness ratio, ̅ 2.5 Effective modulus, = ̅ (GPa) 14.07 5.32 Normal Bond Strength (NBS), ̅ (MPa) 20.28 6.0 Shear Bond Strength (SBS), (MPa) 50.7 6.0 NBS/SBS 2.5 1.0 Friction coefficient between the particles ( μ ) 0.577

Table 2. The experimental results of the uniaxial compression tests for banded Alfas porous stone. h (mm) D (mm) Number of tests Uniaxial compression strength (MPa)

St. deviation (MPa)

110 150 200

54 75

3 4 8

13.36 14.16 16.98

2.47 3.41 3.44

100

24

20

16.98

16

14.16

12

13.36

8

UCS (MPa)

4

50

60

70

80

90

100

D (mm)

Fig. 5. Uniaxial compression strength with respect to the diameters of the specimens.