Valorization of marine sediments in geopolymer mortars: physico-mechanical, microstructural and environmental investigations at laboratory scale

The high consumption of natural sand and the accumulation of mineral wastes in landfills such as dredged sediments make it necessary to valorize the wastes as secondary materials in the field of construction. This work dealt with the valorization of sediments from Sidi Mansour (SM) and Sidi Youssef (SY) Tunisian harbors in geopolymer matrices. The experimental design of mixtures (sand with sediment) at 10 to 25% (w/w) of substitutions was based on the optimum packing density. The mortars were assessed for their mechanical, physicochemical, and environmental properties. The results of compressive strength are always higher than the reference mortar with an optimum at 15% of SM and 20% of SY. In addition, the mercury intrusion porosity (MIP) and porosity accessible to water (PAW) is correlated to the compressive strength values. In addition, the environmental quality of mortars was validated. The SEM analysis of mortars confirms the enhancement of adhesion of the matrix due to structurally stable of Sodium Aluminosilicate Hydrate (N-A-S-H) gel. This study revealed that the substitution of sand by sediments can be considered as a suitable option for improving physico-chemical and mechanical properties of the mortars. Also, the geopolymer binder can be effective to stabilize pollutants in the sediments.

Automated summary

This study investigated the use of sediments from Tunisian harbors in geopolymer matrices. The results showed that substituting sand with sediments can improve the properties of mortars, including mechanical and physicochemical properties.