INVESTIGATION OF THE FRACTURE BEHAVIOR OF GEOPOLYMER CONCRETE REINFORCED WITH RECYCLED STEEL AND GLASS FIBERS

The brittleness of the geopolymer composites is an issue for its widespread use worldwide. Therefore, several types of fibers have been added to the geopolymer mixture to provide a ductile manner. In this work, the recycled steel fibers were employed in a hybrid form with glass fibers to take advantage of the low carbon emission in the production process of recycled steel fibers. The total fiber content was taken as constant 0.6% by volume. Five dissimilar geopolymer batches were handled and two concrete prisms were cast for each batch. Those prisms were tested under three-point loading and the deformed shapes of the specimens’ surface were captured by digital camera to generate the surface displacement field. The fracture characteristics of the notched prisms were criticized in terms of (i) load-CMOD response, (ii) crack progress ahead of the pre-notch, (iii) fracture energy, (iv) ultimate load-bearing capacity, and (v) unstable fracture toughness. Test results revealed that the residual strength, the ultimate load, and the fracture energy of fiber-reinforced geopolymers had a decreasing trend with the increasing recycled steel fiber ratio in the hybrid blend. The reasonable cause of that finding was the heterogeneous distribution of the recycled steel fibers.