Infrastrutture: come rinforzare elementi in ca e cap mediante materiali compositi (FRP)

In the infrastructure sector, the aging of many road and highway networks increasingly calls for monitoring the efficiency of structures and the subsequent need for maintenance interventions aimed at their functional and safe preservation. One of the most frequent methods of intervention is the reinforcement of reinforced concrete elements and caps using composite materials, particularly Fiber Reinforced Polymer (FRP). This article illustrates two different cases of intervention in infrastructure contexts carried out with recently executed carbon materials.

Infrastructure: Reinforcing reinforced concrete elements and caps using composite materials (FRP) The use of Fibre Net fiber-reinforced materials in the infrastructure sector Examples of reinforcement in viaducts using Fibre Net materials The intervention to reinforce the beams of the Cammardà Viaduct in the province of Potenza Cammardà Viaduct is a highway bridge located on the 05 ‘Sicignano-Potenza’ link. It consists of pre-stressed beams and comprises a series of spans supported by differently shaped piers. Three beams with an inverted T-section, which form the structure of the road deck, rest on each pier.

Issues with the viaduct’s damage Some spans of the bridge required the repair of the variable-section pre-stressed beams located on the outer edges of the roadway, i.e., the edge beams, which were more degraded. The necessary intervention focused solely on reinforcing the beams to enhance their structural characteristics.

Reinforcement intervention using CFRP wraps from FIBRE NET The reinforcement intervention involved the installation of Carbon Fiber Reinforced Polymer (CFRP) wraps at regular intervals (40/45 cm spacing) in a vertical pattern across the entire development surface of the beams, totaling approximately 1000 sqm of fabric.

The BETONTEX System from Fibre Net was used for the portions of the beams near the support piers and for an extension of approximately 400-450 cm on both sides relative to the support element. The carbon unidirectional fabric wraps, 30 cm wide, were applied in a single layer as per the design and wrapped around each inverted T-beam across the entire development surface. The installation was carried out according to the predetermined application cycle of the system, which involved a primer epoxy layer followed by a subsequent tixotropic impregnation resin layer.

Example of viaduct reinforcement using the BETONTEX  System

To counteract the “emptying force” that occurs in the reinforcement and could lead to detachment from the beam, FRP connectors called “fiocchi” were used. These fiocchi connectors, fabricated on-site, were also installed at regular intervals and aligned with the width of each wrap, corresponding to the section change, thus ensuring proper adhesion of the fabric to the beam while adequately fulfilling the required reinforcement function

Example of viaduct reinforcement using the BETONTEX  System Fibre Net Materials and Systems for CONSOLIDATION with the BETONTEX  System  with High Modulus FRP fabric, 30 cm width: BETONTEX FB-GV320U-HM, impregnating resin FB-RC02 (class 350/2800C) in a single layer The composite materials used, carbon fiber fabrics, come with a Technical Validation Certificate (CVT).

The flexural reinforcement intervention of the Gallamara and Cornutello Viaducts in the province of Potenza The Gallamara and Cornutello viaducts on S.S. 92-85037 in the province of Potenza consist of a series of spans made up of four pre-stressed reinforced concrete beams with a T-section and lower bulb, spaced at 246 cm intervals, each approximately 30 meters long.

Issues with the viaducts’ damage The condition of the viaducts necessitated maintenance interventions, including the restoration of the concrete in the central parts of the intrados of the road deck and the flexural reinforcement of only the two edge beams of the spans at the lower bulb.

Reinforcement intervention using carbon fabric solutions from FIBRE NET Carbon fiber composite fabrics, CFRP (Carbon Fiber Reinforced Polymer) wraps applied in a double layer, were used to reinforce the beams. Specifically, the intervention involved the following beams:

for the Gallamara Viaduct > beam D of span 15, beams A and D of span 11, beam C of span 5, beam D of span 4, beam A of span 2; for the Cornutello Viaduct > beam A of span 12, beam D of span 9, beams A and D of span 5, beam A of spans 4 and 3. The intervention covered both the lower part of the beam’s bulb, with a width of 50 cm, and both walls of the bulb itself, for a height of 15 cm, requiring the use of approximately 500 sqm of carbon fabric.

Reinforcement intervention using carbon fabric solutions from FIBRE NET The BETONTEX System by Fibre Net was employed for the entire length of each beam, and the application of the carbon unidirectional fabric wraps was carried out according to the predetermined application process of the system. After applying epoxy primer and a subsequent layer of thixotropic impregnating resin, the wraps were laid and impregnated using a debulking roller before applying an additional layer of impregnating resin.

Reinforcement intervention using carbon fabric solutions from FIBRE NET Upon completion of the intervention, a second layer of carbon fabric, with a fresh-on-fresh application process, was applied with complete overlap of the first layer as specified in the detailed design.

Fibre Net Materials and Systemsfor CONSOLIDATION with the BETONTEX  System with High Modulus FRP fabric, 10 cm width: BETONTEX FB-GV320U-HM, impregnating resin FB-RC02 (class 350/2800C) in a double layer The composite materials used, carbon fiber fabrics, are equipped with a Technical Validation Certificate (CVT).