The paper presents the mechanical properties and durability of different types of the FRP rebar’s and their use in construction of bridges.
Traditional material for concrete reinforcement is steel. In recent times, non-metallic fibres have been intensively investigated and some of them used for construction of bridges.
FRP composites are durable materials which are different from the steel reinforcement for their resistance to the electrochemical corrosion. With respect to steel, different mechanical behavior of non-metallic reinforcement, however, involves some drawbacks – namely the lack of thermal compatibility between concrete and FRP reinforcement.
FRP composites belong among anisotropic materials. Their properties depend on the type, volume and alignment of the fibres, the matrix type, form and quality of the construction.
The analysis of causes of failures on German bridges shows that reinforcement corrosion initiated by chlorides makes up 2/3 of all the failures recorded in the bridge construction.
Corrosion of the reinforcement initiated by chlorides is the main cause of the loss of serviceability of bridge structures. In such an environment, fibre-reinforced polymer (FRP) reinforcement can fully replace the traditional steel reinforcement.
Basalt is a type of igneous rock formed by the rapid cooling of lava at the surface of the planet. The production of the basalt and the glass fibres is similar. Crushed basalt rock is the only raw material required for manufacturing the fibre.
It is a continuous fibre produced through igneous basalt rock melt at about 1500 °C. Basalt fibre is a relative newcomer to fibre reinforced polymers and structural composites. It has a similar chemical composition as glass fibre but has better strength characteristics, and unlike most of the glass fibres, it is highly resistant to alkaline, acidic and salt attack, which is making it a good candidate for concrete, bridge and shoreline structures.
Compared to carbon and aramid fibre, it has the features of wider application temperature range -269°C to +650°C, higher compression strength, and higher shear strength. The price of fibres made from basalt is higher than those made of E-glass, but less than S-glass, aramid or carbon fibre and as worldwide production increases, its cost of production should reduce further.
Basalt fibres have high potential and are getting a lot of attention due to its high temperature and abrasion resistance. Compared to FRPs made from carbon, glass and aramid fibre, its use in the civil infrastructure market isvery low.
Robert Sonnenschein, Katarina Gajdosova, Ivan Holly;
Faculty of Civil Engineering, Department of Concrete Structures and Bridges, Slovak University of Technology, Bratislava, Slovakia,