Electrochemical Seawater Mineral Accretion Dynamics: Potentiostatic Control, Phase Thermodynamics, and Self-Healing Kinetics of Biorock Substructures

Conventional marine concrete structures suffer from severe micro-cracking, chloride-induced steel degradation, and immense capital expenditure ($2.5B–$3.0B for large-scale coastal reclamation). Here, we present a rigorous first-principles physical model and experimental framework for low-voltage potentiostatic electro-accretion (Biorock) under ambient marine conditions (1.2–2.4 V DC). By strictly regulating cathodic current density within the optimal window j ≤ 10–15 A/m², we demonstrate thermodynamic phase selectivity, achieving high-density aragonite (CaCO₃) crystallization (compressive strength 80–120 MPa) while suppressing soft brucite (Mg(OH)₂) formation. Furthermore, we establish a quantitative model for autonomous self-healing kinetics: local electrical resistance drop across 200 µm structural fissures induces a localized current surge (j_crack ≈ 120 A/m²), resulting in complete accretion-driven structural closure within 9.5 hours. Economic balance-sheet analysis confirms a CAPEX reduction to $850M–$1.1B for a 50-hectare marine footprint, yielding a net savings exceeding $1.5B with a Carbon-Mineralizing ESG rating.