Effect of hemp fibers on fire resistance of concrete

This study investigated the use of hemp fibers for improving the fire resistance of concrete. The characterization of the fibers was carried out through SEM, TGA/DSC, FTIR and crystallinity index. A reference concrete mixture, polypropylene fibers mixture, and four mixtures with different chemically treated hemp fibers were prepared. The concrete specimens were heated to 400 °C and cooled. Their compressive strength, static modulus of elasticity, residual weight, and residual ultrasonic pulse velocity were then determined and compared. The addition of fibers did not significantly influence the fire resistance of the concrete in terms of the residual properties. Visual observations from scanning electron microscope and microimages of the concrete mixtures showed that the hemp fibers were partially disintegrated within the concrete after being heated; thus, the incompletely disintegrated hemp fibers could reduce crack propagation at high temperatures thus improving the fire resistance of concrete.