experimental study of the effect of water to cement ratio on mechanical properties and durability of nano-silica concretes with polypropylene fibers

This study investigates the effect of nano-silica on mechanical properties and durability of concrete containing polypropylene fibers. herein, the length and the length-to-diameter ratio of used polypropylene fibers were considered fixed and equal to 18 mm and 600, respectively, and the cement content was 479 kg/m^3. the effects of fibers and nano-silica in four different percentages of 0.1, 0.2, 0.3, and 0.4% volume for fibers and 3% for nano-silica in concrete with water to cement ratios of 0.33, 0.36, 0.4, 0.44, and 0.5% were compared and evaluated. in total, more than 425 cubic and cylindrical specimens were made according to astm standards. finally, samples of polypropylene fiber containing nano-silica were tested under compressive loads, flexural strength, indirect tensile strength (brazilian test), abrasion resistance, permeability, and porosity; in addition, their mechanical properties were evaluated. the test results showed a significant improvement of mechanical properties and durability of concrete. compressive strength, tensile strength, flexural strength, and abrasion resistance (of concrete) increased by 55%, 25%, 49%, and 45%, respectively. in addition, a considerable reduction in hydraulic conductivity coefficient by 50% indicates the high durability of these types of concrete.