Kim, Min Ook; Bordelon, Amanda Christine
North Dakota State University; Utah Department of Transportation
Concrete pavements; Fiber reinforced concrete; Fracture mechanics; Mechanical properties; Overlays (Pavements); Polypropylene; Steel
This study aims to investigate the age-dependent changes in flexural and fracture properties of fiber-reinforced concrete (FRC) used in the design of thin overlay pavements. Four different types of steel or polypropylene macro-fibers with different dimensions and different fiber volume contents (0%, 0.5%, and 1.0%) were selected and investigated. No significant changes in compressive strength, free drying shrinkage, coefficient of thermal expansion, and modulus of rupture versus age were identified. Steel FRCs were observed to have a constant or increased residual strength as a function of age while different types or contents of polypropylene FRCs showed varied trends in residual strength versus age. Fracture energy for all FRCs was observed to increase versus age. The residual strength ratio for all FRCs decreased as a function of age, but with only two replicates per age and FRC type, and values were highly variable so no trends were statistically verified at this time. A standard test age, namely 28 days, is recommended due to the changing residual strength ratio parameter used in thin FRC overlay design.