Fire Behaviour of Self-Prestressed Concrete Slabs Reinforced with Carbon Fibre Rein- forced Polymer Tendons

The behavior of concrete under fire varies greatly to that under ambient temperatures. This has led to a vast amount of research being carried on this subject, and a huge amount of progress has been made in terms of understanding the subject through research and experiments.
Concrete, however, has been in a constant state of improvement as a building material. This has led to a wide range of variation of products that can be used with an ever growing list of admixtures that are added to concrete to change its properties. Fiber Reinforcing Polymers have emerged as one of the biggest breakthroughs in the world of engineering.
The use of carbon fibre reinforcement polymers (CFRP) with self consolidating concrete (SCC) has become more common in the past couple of decades. This is mainly due to non corroding nature of CFRP. This means that the amount of cover that is required for corrosion protection can be significantly reduced. Other benefits include the high strength of CFRP which will make the concrete element much stronger. All of this together has made it possible for thin-walled prestressed concrete elements to be used as load bearing structures in building facades.

The use of these elements, though, has been kept to areas where fire is not a big concern such as building facades. This is due to the fact that high performance self consolidating concrete (HPSCC) tends to spall explosively at elevated temperatures. Despite this being relatively well known, research into this subject is scarce. Furthermore, studies have shown that the bond between CFRP tendons and concrete matrix is reduced/lost at elevated temperatures. This is also widely known but not enough research has been carried out to determine why is this and how does the process unfold exactly.

The purpose of this research will, therefore, be to understand the spalling mechanism of spalling of HPSCC and to develop a spalling resistant form of HPSCC that could be used as load bearing items within the interiors of buildings. It will also focus on understanding the bond strength reduction between CFRP and concrete at elevated temperatures in order to establish design criteria based on reduced bond strength.