Influence of water - binder ratios and volume of micro glass fiber on strength and fracture parameters of ultra high performance concretes

An experimental work was carried out to investigate the effects of high volume micro-glass fibers on the mechanical properties and ductility of Ultra High Performance Fiber Reinforced Concretes (UHPFRCs). The aspect ratio and tensile values of the of micro-glass fibers were 722 and 2000 MPa, respectively. Depending on water per binder ratios (w/b) of 0.12 and 0.14, two groups of UHPFRCs containing 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, and 3% fiber volumes were produced and tested for the compressive strength, splitting tensile strength, modulus of elasticity, flexural strength, load-displacement behavior, fracture energy, and characteristic length. The investigational results revealed that the mixes with 1.5% to 3% of micro glass fibers exhibited the best compressive strength of approximately 160 MPa as well as the highest splitting tensile strength. The results also showed that beyond 1.5 % volume fraction of fiber, the improvement of strength properties began to be constant. On the other hand, the mixes with 3% of micro glass fiber displayed a strain hardening, load- displacement behavior with enhanced ductility.