Temperature Impact on Bond Between Steel and Ultra High Performance Concrete
Actual paper describes an experimental research in the field of testing bond behaviour of UHPFRC with temperature impact. High temperature (fire, explosion) or low temperature (freezing) has a fatal impact on final material properties of the concrete. In application made from ordinary concrete exposed to high temperatures polypropylene fibres are often used in case of spalling reduction or its elimination. UHFRPC (Ultra – High Performance Fibre Reinforced Concrete) is very promising material which is used for design very complex structures and elements, because of high material properties and especially high durability and resistance against extreme environment. In this case, a combination of steel fibres (static function) and polypropylene fibres was used for a spalling reduction and elimination, same as in ordinary concrete. Impact of fibre volume to final bond properties was also tested. An extensive research is described in this paper. Large set of results of material properties with connection to final bond behaviour are included. For the tests a normal reinforcement (bars) and prestressing strands were used. UHPC is usually reinforced only by a scattered reinforcement, which replaces ordinary reinforcement. In most application, the UHPFRC is used to increase durability of the structure and reduction of final volume of concrete. There are also many applications where exposition to elevated temperature may occurred (sprayed UHPFRC in tunnel application).Obtained results help to final design of the UHPFRC structure which may be exposed to extreme conditions.
Keywords - Temperature, Freezing, Fire, Material Properties, Bond, UHPFRC