Influence ofCrassostrea gigason the permeability and microstructure of the surface layer of concrete exposed to the tidal zone of the Yellow Sea

Abstract

Concrete exposed to the tidal zone of the Yellow Sea and bearing Crassostrea gigas (CG) with differing areal coverages was investigated for evidence of biologically induced corrosion prevention. The experimental results indicated that both the chloride ion profile and the neutralization depth of the concrete decreased with increasing CG coverage. Moreover, the water absorption rate and the chloride ion permeability of concrete with the original surface intact also declined with increasing degrees of CG coverage. However, the water absorption rates of three concrete samples with 2 mm of the surface layer removed were similar, as was their chloride ion permeability. Mercury intrusion porosimetry tests indicated that CG significantly reduced the pore structure of the concrete surface layer. SEM observation revealed that the CG cementation membrane and left valve were tightly glued to the concrete surface and had a dense structure. Concrete durability indices showed that high CG coverage greatly improved concrete durability.

Influence of the Intrinsic Characteristics of Cementitious Materials on Biofouling in the Marine Environment

“…However, the actions of a biological nature (e.g., colonization of concrete by marine organisms) have been less studied, and less is known about them [24]. The effect of these actions on the durability of concrete in the marine environment remains unclear, but most scientists agree that marine organisms adhered to the concrete surface have a protective effect (bioprotection) against chemical attack in seawater [7,23,[28][29][30][31][32][33][34]; they form a physical barrier that reduces surface permeability. The decrease in surface permeability leads to less-efficient diffusion of aggressive ions (Cl − , Mg 2+ and OH − ), which can increase the durability of a concrete structure in the marine environment [23,29,35,36].…”