Investigation of the usability of luffa fiber and chicken feather fibers in lightweight concrete production

Nowadays, the consumption of natural resources is increasing due to the rapidly developing construction sector. In this case, the need to reuse the wastes in any industry arises in order to support the circular economy and sustainability. In this study, in the production of lightweight concrete, natural fiber waste luffa fibers (LF) and chicken feather fibers (CFF) were substituted into the composite at 2.5-5-7.5 and 10% ratios instead of fine aggregate. Density, compressive, flexural, abrasion resistance, ultrasonic sound permeability (UPV), thermal conductivity, freeze-thaw resistance tests and SEM analyses were performed on lightweight concrete samples with and without fibers. The compressive strength of lightweight concretes containing 2.5% LF was higher than the control concrete, while the strength of all samples with CFF substitution was higher than the strength of samples with and without fibers. Both fiber substitutions contributed to the flexural, thermal transmittance and UPV properties of lightweight concrete. In addition, the hydrophobic properties of CFF increased the freeze-thaw resistance of CFF-substituted specimens and the strong hard keratin structure of CFF increased the abrasion resistance. SEM analysis results and experimental results are consistent with each other. Considering all the experimental results, it is seen that 2.5% substitution rate for LF and 7.5% substitution rate for CFF is ideal. Owing to the ductility that fibers add to lightweight concrete, the brittleness of lightweight concrete will be reduced and its bending resistance will be increased, making it suitable for use in monolithic structures. Since lightweight concrete becomes more porous as the fiber substitution increases, the decrease in thermal conductivity and UPV values indicates that the concrete becomes more insulated. Fiber substituted lightweight concrete will reduce the dead load on the building by reducing the unit weight and will contribute to durability properties such as freeze-thaw and abrasion resistance with CFF substitution.