SOME ASPECTS OF POLYPROPYLENE FIBRE REINFORCED CONCRETE

Abstract

This study looks into some aspects of the polypropylene fibre reinforced concrete, by reviewing past experimental tests conducted by previous students in the University and by carrying out laboratory tests. In the review, mixed and sometimes contradicting findings were noticed, when compared with past researches or general believes regarding fibre reinforced concrete. This showed that more tests and further understanding of the properties of polypropylene fibre reinforced concrete was needed. Also, it was noted that certain variations in testing parameters, such as specimen size and loading rate during test, existed among the tests previously carried out. This might be one reason resulting in variations in the findings. In the laboratory test program, focus was placed on the effect of elevated temperature on the polypropylene fibre reinforced concrete. Concrete specimens were put into a furnace and the furnace temperature was increased gradually to various temperatures, and maintained for various durations. It was observed that polypropylene fibre had negligible effect on the extent of damage, when examined visually, of the concrete specimens subjected to elevated temperature. It was also found, as what many researchers had noted, that polypropylene fibres had negligible effect in enhancing compressive strength of concrete. The compressive strength of polypropylene fibre reinforced concrete specimens was found to be reduced with exposure to higher elevated temperature, and also reduced with longer duration of exposure to elevated temperature. The fibre was found to have some beneficial effect on the flexural strength of concrete subjected to this elevated temperature, but this improvement could not compensate the loss of strength due to high temperature. The experimental test also showed that polypropylene fibre did not have positive effect on the toughness of concrete specimens subjected to 500°C furnace temperature, maintained for 15 minutes. This was seen in terms of maximum deflection observed prior to the flexural failure. This was due to the fact that polypropylene fibres were melted when the concrete was heated to beyond the fibre's melting point.