Mechanical properties of roller-compacted concrete with macro-fibers

The addition of macro-fibers to concrete slabs on ground have been shown to increase flexural capacity, fatigue resistance, reduce crack deterioration rates, and assist in shear transfer across joints and cracks. A laboratory study was performed to determine the benefits of macro-fibers in roller-compacted concrete (RCC) for pavements by measuring the change in RCCs mechanical properties and comparing it to conventional fiber-reinforced concrete for pavements. Six fiber types, four synthetic and two steel, with several fiber geometries were incorporated into RCC mixtures at two dosage levels (0.2% and 0.4% by volume). The addition of synthetic macro-fibers increased the maximum dry density (MDD) over the control RCC mix by reducing the internal friction between aggregates whereas steel fiber had a limited impact on the MDD of RCC. For several fiber types, the resultant RCC with fibers had a statistically significant increase in compressive and split tensile strength relative to the control RCC mix. The addition of fibers did not increase the flexural strength of RCC but did noticeably improve the post-peak and residual strength capacity of RCC. The increases in residual strength were dependent on the fiber type and geometry, similar to the behavior in conventional Portland cement concrete (PCC). The fracture properties of RCC with fibers based on disk-shaped compact tension (DCT) tests were shown to be similar or greater than PCC with fibers which indicates both RCC and PCC pavements, when properly constructed, will have similar fracture and fatigue resistance.