Using fibres to enhance the properties of concrete columns

This paper explores the effects of adding synthetic reinforcing fibres to high-strength reinforced concrete columns and in particular only to the cover of the columns. An experimental program was conducted where seven circular reinforced concrete columns were tested with varying fibre content – one contained no fibres, two contained fibres throughout the cross-section and four contained fibres only in the outer concrete. The other column properties were kept the same for all the seven columns. All seven columns were tested by the application of a concentric, axial compression force. It was found that although only minor improvements were noticeable for a fibre content of 0.1%, the addition of 0.3% polypropylene fibres increased the load at which cover spalling took place. It was also found that the columns containing both fibrous high strength concrete (FHSC) in the outer concrete and HSC in the core exhibited higher levels of ductility than the columns containing FHSC throughout the entire cross-section.