Multiphysical non-destructive evaluation of sustainable sediment-based geopolymer CEB

Abstract

In this study, new Compressed Earth Blocks (CEB) materials are developed from dredged sediments with optimizing mix proportions and geopolymerization. They are evaluated through multiphysical Non-Destructive Testing (NDT) to investigate their electrical impedance, dielectric permittivity and ultrasonic pulse velocity. The effects of compaction pressure, additives (hemp and flax shives and wood chips) and geopolymerization are analyzed, in addition to tracking the drying process at ambient conditions. The results show that NDT effectively assesses CEB composition, with permittivity and impedance revealing moisture levels, which are critical for ensuring durability. Non-stabilized CEB show increased density with compaction pressure rising from 2 to 10 MPa, while dielectric permittivity increases from 3 to 4.5 under ambient conditions. As for fiber-reinforced CEB, they show a good distribution of fibers in the material and a favored orientation, perpendicular to compaction. Similarly to non-stabilized CEB, they exhibit a resistivity ranging from 20 to 50 Ω m. Dry-state geopolymer CEB show the highest resistivity values and fastest ultrasonic wave speeds (up to 2 km/s), improving with higher activator content and density.