The oyster shell is a residue rich in calcium carbonate, which can be reused as a raw material for creating building materials. For this reason, many researchers focused on the incorporation of oyster shell in the composition of composites, as it is a means of contributing to the economic sustainability by reducing the presence of pollution caused by aquaculture waste in the environment, thus increasing the value chain of the construction sector and reducing its carbon footprint. This paper intends to systematize the scientific production related to oyster shell-based composites in construction, carrying out a search using the Scopus tool and a systematic review based on the PRISMA statement. The results show that research on the incorporation of oyster shell into cementitious mortar mixtures, with a focus on its use in concrete, dominates existing scientific research. There is a lack of studies on the incorporation of the oyster shell that address its application as an aggregate or binder in the composition of coating and laying mortars. Most existing research is from Asia, and there is a lack of research in some parts of Europe. In the Americas, Africa and Oceania, no existing studies were found. Despite the growing understanding of the importance of sustainability and economic issues related to products used in the blue circular economy sector, there are still few studies that consider the incorporation of waste or by-products of aquaculture. Future investigations that cover these practical and contextual gaps can contribute to the better use of oyster shell waste and its insertion in the blue circular economy.

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Mortars are still among the most used wall coatings, whether lime-based or cement-based or traditional and prepared in situ or pre-dosed. When these mortars are formulated and characterized, the influence of the substrate on their characteristics is not taken into account. To study the influence of the substrate on the mortar characteristics, it is necessary to apply the mortar on the substrate, and after its hardening process, to detach it, test it, and then compare its characteristics with those of standard specimens subjected to standard tests. The central problem focuses on detaching the mortar without damaging it, in order to obtain specimens suitable for testing. For this, a fibreglass mesh, positioned at the mortar–substrate interface, can be used to facilitate the detachment in the experimental program. The objective of the present study is to understand if the fibreglass mesh influences the characteristics of the detached mortar. The methodology adopted was as follows: mortars were applied to the substrates, both using the mesh (with the net positioned at the mortar–substrate interface) and without using the mesh, and after hardening, they were detached and tested; then, the independent sample t-test was used to evaluate the differences between the results obtained for the mortars applied with the mesh and without the mesh. As a result, it was concluded that the use of the mesh does not significantly influence the macrostructural properties studied. The relevance of the present study lies in the development of an experimental methodology that allows for the characterization of mortar’s behaviour after its application on the substrate, i.e., that enables the substrate’s influence to be considered in the formulation of each mortar.

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