The effect of fiber volume and microfiber type on the fresh and hardened properties of hybrid fiber reinforced self compacting lightweight concrete

It is clear that it would be advantageous to produce self-compacting concrete (SCC), an innovative cement-based composite, as a lightweight concrete, especially in our country, which has a rich pumice resources. Moreover, adding steel fibers to concrete in order to improve the tensile strength of concrete, which is a brittle material, has been frequently studied recently. Within the scope of this thesis study, it is planned to design hybrid fiber self-compacting lightweight concrete (SCLC) and examine the fresh and hardened properties of this innovative concrete. For this purpose, hybrid fiber-reinforced SCLC mixtures including polypropylene (PP) and poly-vinyl alcohol (PVA) fibers together steel fibers at different volume ratios (1.25%, 1%, 0.75%) and different combinations (binary, ternary) as well as Control sample without fiber were designed at a total of 13. In experimental study, fiber volume, fiber type and fiber combination were taken as variable parameters and the properties of fresh (unit weight, slump-sprawl, T500 and J-ring) and hardened concrete (compressive strength, splitting tensile strength, flexural tensile strength, modulus of elasticity and capillary water absorption) of the mixtures were investigated. In conclusion, it was found that the increase in the amount of fiber by volume and fiber combination negatively affected the workability, and the compressive strength of the samples increased with the increase in the amount of synthetic fiber added to the mixtures by volume. The elasticity modulus values of the SCLC samples containing PP were lower than those of the samples containing PVA. In addition, it was observed that as the total volumetric fiber ratio and fiber combinations (binary and ternary hybrid) in the mixtures increased, the splitting tensile strength was positively affected and fiber reinforced SCLC samples with high toughness values exhibited more pronounced multiple crack behavior. In addition to all these, it was observed that the capillary water absorption coefficients of SCLC samples with PVA fiber were higher than those of the samples containing PP fiber reinforcement.