Effects of Polypropylene Fibers on the Post-Cracking Cyclic Shear Response of Concrete Pavement Mixtures

Various methods have been proposed for the design of fiber-reinforced concrete (FRC) pavements, with a specific emphasis on the positive impact of fibers on fatigue performance. However, the contribution of fibers to faulting performance of concrete pavements has yet to be adequately addressed that could result in uneconomical design. One reason for this gap is the limited number of relevant studies, highlighting the need for further research. This study has been designed to examine the post-cracking cyclic shear performance of plain and polypropylene FRC mixtures with slightly over 30 MPa cylindrical compressive strength. Two fiber volume fractions commonly used in literature were considered in this study, as 0.5% and 1.0%. The results show that the fibers improve the post-cracking flexural and cyclic shear performance of concrete, with the extent of improvement depending on the crack width and fiber volume. The use of 0.5% polypropylene fiber provided residual flexural strengths ranging from 1.5 MPa to 1.0 MPa as deflection increased from 0.5 mm to 2.0 mm. Incorporating 1.0% fiber approximately doubled the residual flexural strength compared to the 0.5% fiber content. Relative to plain concrete, FRC mixtures containing 0.5% and 1.0% fiber showed improvements of up to 40% and 60%, respectively, in post-cracking cyclic shear performance for crack widths between 0.2 mm and 2.0 mm. Based on the results obtained in this study and those reported in the literature, a number of suggestions are provided for further studies and FRC pavement design.