Use of oyster shell (Crassostrea gigas) as aggregate replacement for producing environmentally-friendly concrete

• Main Author: Pinto Dabes Guimaraes, Ana Claudia
• Other Authors: Université de Pau et des Pays de l'Adour (UPPA), Université de Pau et des Pays de l'Adour, David Grégoire, Céline Perlot
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2022
• Subjects: Oyster shell; Life cycle assessment; Durability; Concrete; Coquille d'huître; Analyse de cycle de vie; Durabilité; Béton; [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering; Crassostrea gigas
• Online Access: https://hal.science/tel-03703837; https://hal.science/tel-03703837v2/document; https://hal.science/tel-03703837v2/file/thesispintodabesguimaraes.pdf

Due to the depletion of resources, by-products claim attention to be reused or reincorporated in other materials. Cementitious materials are on the top of the list of the most consumed materials which traditionally leads to a high demand for raw materials. In the actual context of net zero emissions target and circularity economy, building materials must be reinvented through a more sustainable approach. Based on this, bio-based materials have been attracting attention to be incorporated into building materials, improving materials properties and providing lower environmental burdens. Within this context, the Nouvelle-Aquitaine region (France), the Arcachon bay shellfish farming Comittee and France University Institute funded the BECCoH project, which aims to assess the potential use of crushed oyster shells (OS) in concrete. The oyster farming activity is largely developed in this region and generates a high amount of waste (shells) due to the maintenance and cleaning process in the farming area on top of food consumption. In general, the shells represent over 70% of the oyster weight, leading to over 700 kilograms of waste per ton of production. Therefore, the BECCoH project has been built to evaluate the reuse of crushed oyster shells as aggregate replacement in cementitious materials, raising awareness in the local community about alternative sustainable solutions for local by-products. In this context, this PhD thesis aims to investigate the use of crushed oyster shells to fully replace fine and coarse aggregate in concrete and to characterise the change of material properties and the potential environmental benefits from this substitution. A new approach is developed to optimise the granular skeleton obtained after oyster shell crushing. This approach consists in combining particle classes in different proportions to obtain better particle packing. Because of the flatness of the crushed OS, traditional methods designed for spherical particles cannot be used for this purpose. Consequently, our strategy is ...