On the Properties Evolution of Eco-Material Dedicated to Manufacturing Artificial Reef via 3D Printing: Long-Term Interactions of Cementitious Materials in the Marine Environment

Abstract

This paper deals with the evolution monitoring of biomass colonization and mechanical properties of 3D printed eco-materials/mortars immersed in the sea. Measurements of tensile strength, compressive strength, and Young’s modulus were determined on samples deployed along the Atlantic coast of Europe, in France, United Kingdom, Spain, and Portugal. The samples were manufactured using 3D printing, where six mix designs with a low environmental impact binder were used. These mortars were based on geopolymer and cementitious binders (Cement CEM III), in which sand is replaced by three types of recycled sand, including glass, seashell, and limestone by 30%, 50%, and 100% respectively. The colonization of concrete samples by micro/macro-organisms and their durability were also evaluated after 1, 3, 6, 12, and 24 months of immersion. The results showed that both biomass colonization and mechanical properties were better with CEM III compared to geopolymer-based compositions. Therefore, the mixed design optimized according to mechanical properties show that the use of CEM III should be preferred over these geopolymer binders in 3D printed concrete for artificial reef applications.

Sustainable And Bioengineered Concrete For Armor Units Of Low-Crested Structures

“…Favorable early colonization was observed in concretes containing limestone and granite aggregates (Natanzi et al, 2021). Limestone and glass sand (0-0.3 mm) used as a substitute for 30% sand also showed good mechanical concrete properties to construct artificial reefs (Boukhelf et al, 2022), with better bio-colonization response observed after two years in glass sand concrete than limestone concrete. Crushed glass sand from broken car windshields, used as recycled fine aggregate to partially replace limestone sand in cement mortars, showed high environmental acceptability as artificial reef material while concrete containing shells showed the highest toxic effect (Santos et al, 2023).…”

“…The most investigated cements in the literature are CEM III (slag cements), of which some advantages have already been presented in section 2. These are: (1) increase durability of concrete due to its microstructure after hydration (Boukhelf et al, 2022), (2) increase early biological colonization of concrete due to its lower alkalinity compared to Portland cement (Natanzi et al, 2021), which provides a better substrate for attachment and growth of marine organisms (Rupasinghe et al, 2024), (3) fulfill inert landfill limits in ecotoxicological analysis, from which CEM III/B 32.5 N-SR is recommended for use in artificial reefs (Santos et al, 2023), (4) contain statistically lower amounts of metal released in controlled leaching experiments compared to concrete containing pulverized fly ash or Portland cement (McManus et al, 2018).…”

Analytical Review of Geopolymer Concrete: Retrospective and Current Issues

“…The influence of the content of the activator in relation to the binder and the proportion of water to the binder were investigated. The best strength characteristics were obtained at a water-to-binder proportion of 0.33 and an activator amount of 8% of the binder volume [ 191 ]. The addition of GGBS to geopolymer concrete based on FA showed an improvement in its microstructure and strength but had almost no effect on the deformability of the material [ 192 ].…”

Artificial reefs through additive manufacturing: a review of their design, purposes and fabrication process for marine restoration and management

“…It is not feasible to exclude this component from the mixture. Common binders like polymers and resins may harm marine life, but recent studies have developed bio-friendly binders (Ahn et al , 2021; Boukhelf et al , 2022; Salari et al , 2022) aimed at reducing environmental impact in marine applications such as ARs. BJ has been used to build ARs using marine-safe materials such as cement, mineral composites, sand or clays (Boskalis, 2017).…”