Effects of three different nanomaterials on the properties and microstructure of sludge based geopolymers.

This study delves into the influence of various nanomaterials on the mechanical performance and durability of sludge-based geopolymer. In terms of overall strength, it was evident that nanosilica (NS), when introduced at the same doping level, exhibited the most significant enhancement in mechanical properties, surpassing nano-calcium carbonate (NCC) and graphene nanoparticles (GNPs). For instance, the addition of 2% NS resulted in a remarkable increase of up to 108.2% in compressive strength and 69.9% in flexural strength. Furthermore, the early reaction rate of sludge-based geopolymers was positively affected by the incorporation of NS, NCC, and GNPs. After 28 days, thermogravimetric analysis demonstrated that the mass loss for the reference sample and geopolymers enhanced with NS, NCC, and GNPs was approximately 15.06%, 14.78%, 14.85%, and 14.95%, respectively. Regarding durability, the sludge-based geopolymers displayed enhanced resistance to sulfate erosion and freeze-thaw cycles. This improvement was attributed to the ability of nanomaterials to fill pores and promote hydration reactions, resulting in a denser matrix. This paper delves into the influence of nanomaterials on the gel microstructure and gel micromechanical properties, shedding light on the mechanisms responsible for the enhanced mechanical and durability properties. It also presents a comparative analysis of results at different doping levels, offering a promising solution for waste treatment and carbon emission reduction, while making a compelling case for practical engineering applications. • First study of mechanical and durability properties of nanomodified sludge-based geopolymers. • Nanomodified sludge-based geopolymers can be used for practical engineering applications. • The mechanical properties of nanomodified sludge-based geopolymers depend on factors such as gel strength, pore filling and chemical bonding. [ABSTRACT FROM AUTHOR]