Quince Seed and Flaxseed Mucilage as Natural Viscosity-Modifying Agents in Cementitious Composites: Rheological, Fresh-State and Mechanical Performance

This study evaluated the feasibility of using mucilage derived from plant seeds as a viscosity-modifying agent in cementitious composites. Mucilages derived from quince seeds (quince seed mucilage, QSM) and flax seeds (flaxseed mucilage, FSM)-which are readily available, low-cost, and sustainable sources of hydrocolloids-were dried and ground into powder, then used as viscosity-modifying agents in cementitious mixtures. Their effects on the mortars were compared with those of welan gum (WG), which is commercially used as a viscosity-modifying agent. According to the results, at a 0.1% dosage QSM and FSM reduced the spread diameter by 63% and 61% respectively, and significantly increased the V-funnel flow time, which exceeded 40 s. Rheological measurements revealed that all additives used increased viscosity, yield stress, and thixotropy. QSM increased plastic viscosity by approximately 8.9 times, and FSM by approximately 8.4 times. While the additives caused only a minor reduction in compressive strength (below 8%), they increased the resistance to segregation and extended the setting time. It was concluded that QSM and FSM can be used as viscosity-modifying agents in cement-based composites because they modulate the rheological properties without altering the mechanical properties of the mortars.