Long-term performance of cementitious pastes incorporating dredged Amazon River sediment as a mineral filler

Abstract

Dredged sediments represent a significant environmental liability in fluvial systems, especially in the Amazon region, where dredging operations are required to maintain navigability. This study evaluated the potential use of Amazon River dredged sediment (ARS) as a mineral filler in cementitious pastes. The sediment was dried, ground, and used as a partial replacement for Portland cement at levels of 10%, 20%, and 30% by mass. Chemical, mineralogical, and particle size characterizations were performed, along with the evaluation of fresh and hardened-state properties at 28 days and after 2 years of curing. The results showed that ARS presents low pozzolanic reactivity and predominantly inert behavior, acting mainly through physical effects related to particle packing and matrix densification. Sediment incorporation increased paste flowability without significantly affecting setting time. Although an initial reduction in compressive strength was observed, after 2 years the mixtures containing ARS exhibited mechanical and physical performance comparable to the reference material. The results indicate that ARS has potential for application as a mineral filler in more sustainable cementitious materials.