Effect of sugar beet press filter waste on mechanical and durability properties of engineering cementitious composites

In this thesis, the effect of partially replacing fly ash, used as one of the main binders in high-strength and high-ductility Engineered Cementitious Composites, with sugar beet press filter waste, a by-product of the sugar industry in our country, on the fresh properties, mechanical performance, and freeze–thaw resistance of ECC was investigated. Four different mixtures were prepared: a reference mix without press filter waste and mixes in which fly ash was replaced with press filter waste at rates of 10%, 20%, and 30%. Some specimens were not subjected to freeze–thaw cycles, while others were exposed to two different levels of freeze–thaw cycling, namely 60 and 120 cycles. Mini flow table tests were conducted to evaluate the fresh properties. To assess the mechanical behavior, compressive strength and ultrasonic pulse velocity tests were performed on specimens at 7, 28, and 56 days. Flexural strength, direct tensile strength, and matrix fracture toughness tests were carried out on 28-day specimens. Mass changes before and after freeze–thaw exposure were also measured. Although compressive strength and ultrasonic pulse velocity decreased with increasing press filter waste content, improvements were observed with prolonged curing and repeated freeze–thaw cycles. Flexural performance decreased with press filter waste substitution in non-exposed samples; however, under low freeze–thaw cycles, substitution up to a certain level improved flexural performance, while higher cycle numbers limited this improvement. Tensile strength increased with press filter waste replacement up to a certain substitution ratio, regardless of freeze–thaw exposure. Matrix fracture toughness decreased with press filter waste addition in non-exposed and 60-cycle specimens, but increased after 120 freeze–thaw cycles. Furthermore, regardless of the replacement level, most samples showed a slight mass gain between 0.01% and 1.6%, while those that experienced mass loss exhibited only minor reductions between 0.03% and 0.3%. Consequently, the partial replacement of fly ash with press filter waste was found to be favorable in terms of both sustainability and cost, considering its satisfactory performance under freeze–thaw exposure.