Issue 10

B. Chiaia et alii, Frattura ed Integrità Strutturale, 10 (2009) 29-37; DOI: 10.3221/IGF-ESIS.10.04 34 these couples were tested, respectively, at σ 3 = 0 MPa and σ 3 = 1 MPa. Two Sismabeton cylinders (HC0 and HC0b), with H =140 mm and D =70 mm, were tested in uniaxial compression. The properties of each specimen are reported in Tab. 2. Table 2 : Mechanical and geometrical properties of the specimens tested in uniaxial and triaxial compression. T EST RESULTS ig. 6 rep orts the stress-strain relationships obtained from the specimens made respectively with Sismabeton (Fig.6a), normal concrete (Fig.6b) and self-consolidating concrete (Fig.6c). The higher the confinement, the higher the value s of f c and  c1 , which are reported, together with Young’s modulus E c , i n Tab. 3. In all the cases, after the peak stress f c , a remarkable strain softening branch can be observed in the  c -  c diagrams. Although Sismabeton is fiber-reinforced, its compressive strength does not differ substantially from those of ordinary and self-consolidating concrete. However, the post peak response of Sismabeton appears more ductile. Only when the confining pressure  3 increases, does the ductility of NC and SC increase. By comparing all the post-peak branches reported i n Fig.6, it seems that the post-peak branches of SC and NC specimens in the presence of  3 =1 MPa are more or less the same of Sismabeton without any confinement. Figure 6 : The stress-strain relationships of Sismabeton, NC and SC. Specimen f c (MPa)  c1 (%) E c (MPa) 0NC0 19.4 0.293 24000 0NC1 30.5 0.473 23000 0SC0 20.1 0.479 17000 0SC0b 23.2 0.372 23000 0SC1 36.4 0.604 19000 0SC1b 32.0 0.696 27000 HC0 21.8 0.352 19000 HC0b 22.2 0.534 20000 Table 3 : Mechanical properties measured in the tests. Specimen H (mm) D (mm) Type of concrete  3 (MPa) NC0 140 70 NC 0 NC1 140 70 NC 1 SC0 140 70 SCC mix 1 0 SC1 140 70 SCC mix 1 1 SC0b 140 70 SCC mix 2 0 SC1b 140 70 SCC mix 2 1 HC0 100 50 Sismabeton 0 HC0b 100 50 Sismabeton 0 F