Impact of wetting and drying cycles on flexural characteristics of wastepaper fiber-reinforced concrete containing metakaolin

In this study, metakaolin was utilized as a substitution of 20% cement to produce wastepaper fiber-reinforced concrete. The wastepaper was derived from discarded plasterboard as a construction and demolition waste. Various concentrations of wastepaper fibers (0-2.5% by weight of the binder) were used to develop a more sustainable concrete with properties comparable to traditional concrete when exposed to accelerated aging through wetting and drying cycles. Following exposure to 50 cycles, the optimum concentration of wastepaper fiber is found as 1.5%, leading to 53%, 56%, 68% and 61% enhancement in flexural load bearing capacity, fracture toughness, fracture energy and compressive strength of developed concrete relative to conventional concrete, respectively. For all the metakaolin-based mixes, when the number of cycles increases compressive strength, flexural strength and load bearing capacity, and toughness increase. Furthermore, the results revealed that using 20% metakaolin as partial substitute of cement and 1.5% wastepaper fiber develops concrete with comparable mechanical properties to the plain conventional concrete. This concrete cannot only reduce the growth in global warming potential by 12%, but also demonstrates favorable performance across various environmental impact categories, from abiotic depletion to freshwater ecotoxicity.