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

Abstract

This paper presents an assessment of recycling thermally treated fluvial sediments as a supplementary cementitious material (SCM). Different calcination temperature was conducted ranging between 450 and 950 °C, and for each, a detailed characterization was carried out. Subsequently, different 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 show that blended cement based on CS at 750 °C provided the most favorable hydration kinetics, highest compressive strength among the other mixtures due to the highest portlandite consumption by pozzolanic reaction. An optimization design was tested to maximize the substitution rate of CS. The multivariable function results suggest a replacement rate up to 20% to produce a blended cement equivalent to that of CEM II 52.5 N, and up to 30% to produce a CEM II 42.5 N. The reported techno-environmental findings corroborate the use of CS as SCM and motivate future research on their effect on concrete properties.