Impact Resistance and Mechanical Properties of Hybrid Steel and Polypropylene Fiber Reinforced Geopolymer Concrete

and polypropylene fibers on the behaviour of geopolymer concrete which was evaluated through mechanical properties and impact resistance. A total of 18 mix designs were examined to obtain an optimal constituent mixes corresponding to high mechanical strength and impact resistance. Two types of fibers namely steel (ST) and polypropylene (PP) fibers were used in mono as well as in steel – polypropylene hybrid form, the major parameters studied were the fiber dosage and incorporation of different fibers. By embedding each of steel and polypropylene fibers with various volume fractions of 0.2%, 0.4%, 0.6%, 0.8%, 1% and 1.2% to the geopolymer concrete mixture. For a hybrid system, the polypropylene fiber was replaced gradually with steel fiber at a rate of 0.2% by volume. Experimental results indicated that fiber addition improves the mechanical properties and impact performance of the fiber reinforced geopolymer concrete, the results also show that the mechanical properties of hybrid fiber reinforced geopolymer concrete (HyFRG) are lower than that of 1.2% steel fiber reinforced geopolymer concrete (SFRG) and the hybridization of steel fiber can improve the impact resistance of polypropylene fiber reinforced geopolymer to different degrees. The best result obtain by incorporation of 1% steel+0.2% polypropylene fiber exhibited the highest impact resistance at Z1 and Z2 by 10.7 and 8.9 times respectively.