Abstract: “This paper investigates the effect of thermal loading on the tensile strengths of normal and high strength concrete with and without polypropylene fibers. The unstressed residual split and flexural tensile strength of concrete is determined by testing cylinder and prism specimens. The specimens were subjected to single heating-cooling cycle with a hold period of 3 hours at 2000C and were cooled in the furnace before testing the specimens for the residual split and flexural tensile strength of concrete. Similar treatment was carried out on the specimens at 4000C, 6000C and 8000C and their residual tensile strength’s were determined. Specimens were also prepared for determining the tensile strengths at room temperature. It has been observed that with the increase in the thermal loading or temperature, the flexural and split tensile strength experienced significant losses. The loss was found to be higher for stronger concretes. Flexural tensile strength was observed to experience a sharp”

Keywords: High temperature; normal strength concrete; high strength concrete; polypropylene fibers; split tensile strength; flexural tensile strength