Issue 50

A. Marinelli et alii, Frattura ed Integrità Strutturale, 50 (2019) 438-450; DOI: 10.3221/IGF-ESIS.50.37 443 Span/Depth Ratio Length (mm) Span (mm) Depth (mm) Notch length (mm) 5/2 250 200 80 27 450 400 160 53 850 800 320 160 4 250 200 50 17 450 400 100 33 850 800 200 67 6 250 200 33 11 450 400 66 22 850 800 133 44 Table 1: Second stage of experimental investigation - Portland limestone test specimen specifications. Figure 7 : (a ) Three-point bending test configuration; (b) actual test set-up (200 mm span). EXPERIMENTAL RESULTS Comparative study: material characterization and combined results ased on non-destructive testing results as described above, average values of fundamental material properties were derived for both Portland limestone and Corsehill sandstone (Table 2), after 3 repetitions of each type of test. As expected, given the highly inhomogeneous and porous nature of Portland limestone, Corsehill sandstone has a greater apparent density than Portland limestone, although Portland limestone has a higher density of solids. The use of an ultrasonic pulse velocity (UPV) test instrument confirms the higher porosity of Portland limestone, as the average velocity of the ultrasonic waves passing through this material’s samples is 4.74 mm/μs, significantly higher and presenting also a greater variance compared to the almost stable 2.81 mm/μs recorded for the more uniform Corsehill sandstone samples. These findings are in good agreement with other data existing in the literature [19]. Material properties Portland limestone Corsehill sandstone Apparent Density (kg/m 3 ) 1955.14 2279.91 Density of solids (kg/m 3 ) 3078.42 2493.79 Open Porosity (%) 15.87 7.94 Total Porosity (%) 36.49 8.58 Modulus of Elasticity (3PB) (MPa) 8340.54 2884.45 Modulus of Elasticity (Pundit) 11820.89 4778.48 Compressive Strength (MPa) 36.90 37.93 Flexural Strength (3PB) (MPa) 4.91 5.43 Flexural Strength (4PB) (MPa) 4.13 5.43 Table 2: Comparison of fundamental material properties for Portland limestone and Corsehill sandstone. (a) (b) B