Experimental Tests on Fibers Influence on the Size Effect on Shear - On Shear Behavior of Structural Elements Made of Steel Fiber Reinforced Concrete - page 75

Chapter 5
Experimental Tests on Fibers Influence
on the Size Effect on Shear

5.1 Introduction

In this chapter it will be discussed the possibility of steel bers to mitigate the size

effect in large beams. For that, an experimental program consisting in 9 beams with
h = 500, 1,000 and 1,500 mm, made with three types of concretes with 0, 50 and
75 kg/m 3 of

bers was done. The beams were tested with a/d = 3 for all cases. The
concrete was manufactured in a concrete plant of Italcementi Group, while the tests
were carried entirely at the laboratory “ Pietro Pisa ” of the University of Brescia.

5.2 Materials

The beams have been casted in different times using three different mix design.
Speci

c concrete proportions have been used for mixing plain concrete (samples
PC) and bers of 50 kg/m 3 (samples

FRC50) and 75 kg/m 3 (samples FRC75). All mixtures have been mixed in a precast
manufacturing plant of Italcementi Group © (Fig. 5.1 ) situated in Mompiano
(Brescia) and concrete was provided to the university by mixing trucks.
The materials used were a CEM I 42.5R cement type, sand 0/4 mm and coarse
aggregates with a maximum size of 16 mm. The concretes had a water/cement ratio
equal to 0.41. As it can be seen in Table 5.1 , mix designs only differ on the amounts
of

ber reinforced concrete with an amount of

bers used were low carbon steel with hooked-
ends: 50 mm length, 0.8 mm diameter, and a nominal aspect ratio (length/diameter)
equal to 62.5. Fibers were provided by La Matassina Group © and its product

bers and superplasticizer. The

“ La

Gramigna ® ” bers was used (Fig. 5.2 ).

Table 5.1 shows the three concrete compositions.
Table 5.2 show the

bers geometry and their characteristics.