Experimental Tests on Fibers Influence on the Size Effect on Shear - On Shear Behavior of Structural Elements Made of Steel Fiber Reinforced Concrete - page 77

Table 5.2 Characteristics of
the bers adopted

Designation 50/0.80

Type of steel Carbon

Shape Hooked

Minimum tensile strength (MPa) 1,100

Length (mm) 50

Diameter (mm) 0.8

Aspect ratio l/ / 62.5

5.3 Concrete Properties and Production Control

For evaluating the mechanical properties of concrete, an exhaustive production
quality control took place in the experimental program. Cylinders, cubes, round
panels and prismatic specimens were produced, as shown Fig. 5.3 .
The following tests were done: the slump-

ow (EN 12350-8), compressive
strength (EN 12390-3) and three point bending (EN 14651). The following was
obtained from the

fl

fl exural test: the limit of proportionality (f ctl ) and the residual

fl exural tensile strength (f R,j ) which corresponds to the crack mouth opening dis-

placements (CMOD) linked to the crack openings (in mm) of 0.5, 1.5, 2.5 and 3.5
(j = 1, 2, 3, 4 respectively). Figure 5.4 exhibits the dimensions of the prismatic
specimens according to the EN 14651, while Fig. 5.5 shows a prismatic specimen
during the three point bending test (EN 14651).
Figure 5.6 exhibits the curves obtained by the three point bending tests. Beyond
the peak load, it can be observed the clear differences between plain and ber

reinforced concrete. Plain concrete has a behavior totally brittle after the peak;
namely, once the specimen cracks, immediately the specimen breaks in two blocks,

Fig. 5.3 Round panel and
cylinder, cubic and prismatic
specimens just produced