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The post-cracking tensile behavior of polypropylene fiber reinforced concrete (PFRC) was investigated through an experimental study; special attention was devoted to the effects of fiber distribution and orientation on samples performance. In this regard, an experimental campaign based on uniaxial tensile tests (UTTs) on notched cylinders as well as three-point bending tests (3PBTs) on notched beams was carried out. Uniaxial post-cracking tensile laws retrieved both directly (UTTs) and indirectly (3PBTs) were compared. In the latter case, the fracture energy was higher because of the strongly dependency between PFRC post-cracking performance and fiber distribution and orientation. In addition to cast cylindrical samples, core samples were directly drilled from the beams and tested under UTTs in order to compare their post-cracking performance with that obtained by flexural standard tests on notched beams.

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The state of road infrastructures in many advanced countries is rapidly changing under the impulse of massive funding from governments, eager to have more efficient and safer transportation systems. The use of well-known materials such as fibre-reinforced concrete (FRC) is finding a growing space for structural rehabilitation of bridges; the adopted material is often defined as High performance fibre reinforced concrete (HPFRC) due to its enhanced performance. The paper presents the principal findings of an EU-funded project that involved the repair of two road bridges in Italy using HPFRC. The project has successfully carried out the jacketing of bridge piers and cap-beams, heavily damaged by corrosion, with a new HPFRC layer of reduced thickness (40-60 mm) and limited use of steel reinforcements. Experimental tests carried out in the laboratory of the University of Brescia on 1:2 scaled specimens have shown the possibility to increase the load bearing capacity of the cap beams (with respect to vertical loading) up to 73%, with moderate effects on the change in stiffness and ductility of the existing structure. Based on field and laboratory experience, the article eventually presents some new challenges for the use of HPFRC in the reduction of environmental impact of construction industry.