The Effect of Different Types of Fibers and Cement Substitutes on High-Performance Concrete Cured in Standard, Thermal, and Sulfate Conditions

Abstract In this study, the workability and mechanical characteristics of concrete containing different types of fibers and cement substitutes of concrete under standard, thermal, and sulfate environment curing conditions were compared. Normal concrete was made with a water-to-cement ratio of 0.43, and high-performance concrete was produced with smaller water-to-cement ratios (0.38, 0.33, and 0.28). Macro steel fibers in three different amounts and with two length sizes (60 mm and 30 mm), including polypropylene fibers (PP), and high-performance polypropylene fibers (HPP) in combination with steel fibers, blast furnace slag, and silica fume were used as cement substitutes. The tests performed include slump tests, compressive, flexural strength, and Brazilian tensile and microstructure images. Results showed that thermal curing (without moisture) reduces compressive, tensile, and flexural strength compared to standard curing conditions, and using the steel fibers this weakness was not reduced. In standard curing, by adding steel fibers, the mechanical properties increase significantly, and by increasing the percentage of steel fibers, the mechanical properties also improve. Concretes with a combination of different types of fibers did not favorably affect the mechanical properties of concrete compared to steel fiber concretes.