Research on the BEM Reinforcement Mechanism of the POSF Method for Ocean Stone Construction

The Planting Oysters to Strengthen the Foundation (POSF) method, as a construction technique for coastal stone structures in the Northern Song Dynasty of China (1059), has been preserved to this day. Exploring its long-term reinforcement mechanism can provide theoretical support and practical guidance for the protection and sustainable development of world marine cultural heritage. This article uses Crustacean Ash Triad Clay (CATC) from Shihu Ancient Wharf in Quanzhou as a case study and conducts a systematic investigation using XRD, Raman, SEM-EDS, FTIR, and 16S rRNA high-throughput sequencing. The results show that CATC has a core skeleton of 94.6% quartz, with potassium feldspar, dolomite, and metal compounds as auxiliary components; that its 19.04% porosity provides enrichment space for positively charged ions and tide-borne microorganisms; that electrostatic adsorption between barnacle adhesive and the material achieves physical reinforcement; and that microbial metabolism promotes dolomite formation, producing chemical reinforcement. Thus, the ternary coupling of Biology–Environment–Materials forms a BEM long-term reinforcement mechanism suitable for low-carbon construction in the ocean.