Additive Manufacturing of Geopolymers Modified with Microalgal Biomass Biofiller from Wastewater Treatment Plants

Abstract

This paper deals with the additive manufacturing of metakaolin-based geopolymers and with the use of microalgal biomass from wastewater treatment plants as biofiller in this kind of cementitious material. The study was developed following the evolution stages of the material, which was prepared and printed as a soft paste and then hardened thanks to an inorganic polymerization reaction (geopolymerization). Thus, the characterization techniques adopted encompassed rheometry, mechanical tests performed on the hardened material, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and mercury intrusion porosimetry (MIP). Microalgal biomass addition, evaluated in this study at 1, 3 and 5 php with respect to the powder weight, affected both the properties of the fresh and of the hardened material. Regarding the former aspect, biomass reduced the yield stress of the pastes, improving the ease of the extrusion process, but potentially worsening the ability to build structures in height. When hardened, geopolymers containing microalgae showed mechanical properties comparable to the unfilled material and a microstructure characterized by smaller pores. Finally, a printing test was successfully performed with a larger printer to assess the feasibility of producing large-scale structures. Taking into account these results, this study demonstrates the possibility of using microalgal biomass as biofiller in geopolymers for additive manufacturing.

Embedding Bio-Filler Materials to Enhance Physical-Mechanical-Thermal Properties of Concrete

“…3b and 3c, respectively. Adding bio-fiber into concrete matrix affects to increase tensile strength and thermal resistance suitable for use as insulation materials consistent with the results reported by E. Agnoli et al [7] and N. Nciri et al [8].…”

Implementing FDM 3D Printing Strategies Using Natural Fibers to Produce Biomass Composite

“…The studies [ 19 , 31 , 32 , 33 , 43 , 45 , 46 , 48 , 53 , 57 , 58 , 60 , 61 ] were missing either one or both of information (fiber wt% or maximum tensile strength) and these studies [ 56 , 59 , 65 , 67 , 73 ] did not include tensile strength as a part of their evaluation.…”

“…The improvement in the mechanical properties was attributed to the fact that irregular grooves and cracks induced by the modification of bamboo fibers facilitated the infiltration of polymer into the fibers because of the strong capillary effect. Agnoli et al [ 73 ] used microalgal biomass with lignin in geo-based polymer metakaolin and alkaline activator. When hardened, this composition displayed mechanical properties comparable to the unfilled material and a microstructure with smaller pores.…”

Additive Re-Manufacturing of Mechanically Recycled End-of-Life Glass Fiber-Reinforced Polymers for Value-Added Circular Design

“…For the purposes of this paper, the 3D printing technology will be called liquid deposition modeling (LDM) to state that the material in the form of a viscous liquid will be deposited to fabricate a 3D model layer by layer. This technology enables the use of a large material range, which includes ceramics, concrete [22], thermoset polymers, elastomers, and composite materials [11,23,24]. In this work, an LDM technology assisted by UV light (UV-LDM) allows the 3D printing of UV-and thermo-curable resins loaded with mechanically recycled GFRPs obtained by shredding EoL wind blades.…”