PSI - Issue 55

Poliana Bellei et al. / Procedia Structural Integrity 55 (2024) 96–102 Poliana Bellei et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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The LCA is an important tool in modern industrial environmental management (Löfgren et al. 2011). Increasingly, industries are using LCA to reduce overheads, consequence of the life cycle of goods and services, in addition to improving the competitiveness of the company's products. The LCA process is also used to improve product design for a better choice of materials, technologies, design criteria and to consider recycling (E.C. 2023). Based on the results generated by the LCA, it is possible to promote a more responsible project, mitigate environmental impacts, and reduce the use and release of toxic materials (EPA. 2023). This paper studies oyster shell, in the form of powder or aggregate waste and it compares mortars made with varying percentages of traditional materials substituted by incorporated oyster shell. The case study was conducted in the Algarve region, located in southern Portugal. This work is part of the activities to be carried out under the EEA granted Shellter project. The project intends to discuss the potential of incorporating oyster shells waste in the development of construction materials in a circular economy model, joining Nofima AS (Norway) and Instituto Superior Técnico, University of Lisbon (Portugal). 2. Study methodology – LCA case study The methodology employed in this study is in line to the European Standard EN 14040 (2006), which outlines the principles and framework for a life cycle assessment. In the LCA study, oyster shell was considered as a component of the coating mortar, and was harvested on Culatra Island, Algarve, in the south of Portugal. Algarve region was chosen because it is the largest aquaculture producer in Portugal. The Global Warming Potential (GWP) was identified for three different types of oyster shell mortars produced in Faro, the capital of the Algarve region. The Life Cycle Assessment (LCA) modeling was conducted using SimaPro 9.4.0.2 software, and the Ecoinvent 3 database to create processes that are relative to the oyster shells treatment and sand. To understand the processes of Natural Hydraulic Lime, it was used a reference (Miniera. 2020). In this work, the life cycle covers from the cradle to the gate. The GWP were assessed from the extraction of necessary raw materials from their natural environment (except for the oyster shell) to the associated transportation and manufacturing processes. To address this, an approach was employed, involving a synthesis of the identified and treated impacts, which were then integrated in Excel to yield results that are both compatible and realistic. With advances in research into the application of other biomaterials in the composition of mortar for civil construction, interest in the use of oyster shell as a substitute for binder or aggregate in the manufacture of mortar for civil construction has been awakened, in order to contribute to the reduction of environmental impacts (Bellei et al. 2023). In the manufacturing stage, the objective was to produce coating mortars by replacing percentages of traditional materials with oyster shell. A conventional mortar was considered to be composed of: Natural Hydraulic Lime 3.5 (binder), Sand (aggregate), and Water (CONTROL). Three solutions were analyzed, each of them containing percentages of oyster shell in the composition, but varying these percentage in the production processes involved. In Solution 1: 24% of the hydraulic lime is replaced with oyster shell powder (24% NHL-OSP); in solution 2: 24% of the hydraulic lime is substituted with calcined oyster shell powder (24% NHL-COSP); and in solution 3: 30% of the sand is replacing by an oyster shell aggregate (30% S-OSA). 3. Results and discussions 3.1. Life cycle of oyster shell mortars Extraction of raw materials : in this study the GWP of the production of natural hydraulic lime and the extraction of sand were considered according to the Section 2. The stage of raw material production from oyster shells was not considered in the LCA of this study. This is because its primary purpose is not construction but rather food consumption. Once the shell becomes a waste product for the environment, either through population consumption or mortality during harvesting by oyster farmers, it can potentially become an attractive biomaterial for other industries. Furthermore, after the oyster shell arrives at the laboratory, the cleaning and drying stages were not considered in this study. Currently, oyster farmers leave oyster shells near their sheds, and the shells are naturally cleaned and dried. These and other data were obtained from interviews conducted in the Algarve region. The interviews with