Fluvial Sediments as SCMs: Characterization, Pozzolanic Performance, and Optimization of Equivalent Binder

This paper presents an assessment of recycling of thermally treated fluvial sediments as a supplementary cementitious material (SCM). Different calcination treatments were conducted with temperatures ranging between 450°C and 950°C. For each calcined sediment, a detailed characterization was carried out. Subsequently, blended cements containing 25% calcined sediments (CS) were prepared and tested, including portlandite consumption, hydration kinetics, and compressive strength development (41 and 52 MPa at 7 and 90 days, respectively). The results showed that blended cement based on CS at 750°C provided the most favorable hydration kinetics and the highest compressive strength. An optimization design of experiment was followed to maximize the substitution rate of CS. The resulting multivariable function suggests a replacement rate up to 20% to produce a blended cement equivalent to CEM II 52.5 N, and up to 30% to produce a cement equivalent to CEM II 42.5 N. The reported technoenvironmental findings corroborate the use of CS as SCMs and motivate future research on their effect on concrete properties.