Effect of high volume fly ash on mechanical properties of fiber reinforced concrete

This paper reports the effects of incorporating high volume fly ash in fiber reinforced concrete. Fly ash was mixed as a partial fine aggregate replacement of approximately one third of the fines volume. The fibers were polypropylene or steel fibers at a maximum proportion of 1% by volume of the concrete. The results showed that fiber reinforced concrete that included high fly ash volume achieved compressive and tensile strength values that are more than double those of concrete without fly ash. Values of other mechanical properties have also achieved significant increase due to fly ash addition. It is suggested that a large quantity of fly ash is necessary to enhance the efficiency of fiber reinforcement. Polypropylene fibers resulted in gains up to 50% while steel fibers achieved gains up to more than 100%. This enhancement is believed to be due to the microstructural modification and densification in the transition zone between the matrix and the fibers.