The premature deterioration of reinforced-concrete structures exposed to chloride and organic salts is a coupled physicochemical, electrochemical, transport, and mechanical phenomenon. Chloride ionspenetrate concrete through diffusion, capillary suction, convection, and electromigration. Organic salts, such as acetates and formates used in de-icing systems, may produce additional deterioration through pore-solution modification, complexation with cement hydration products, alteration ofcalcium–silicate–hydrate phases, osmotic pressure, accelerated moisture transport, and electrochemical interaction with reinforcing steel. This paper presents an advanced theoretical framework for describing the early deterioration of cementitious structures using reactive-transport theory, electrochemical thermodynamics, porousmedia physics, and fracture mechanics. The proposed model couples the Nernst–Planck equations,Darcy flow, moisture transport, chloride binding, chemical equilibrium, carbonation, corrosion kinetics, and damage evolution. The general governing system is formulated as a nonlinear chemo–hygro–thermo–electro–mechanical problem.The deterioration process is governed by the interaction between free ions, bound ions, pore-fluid saturation, temperature, electrical potential, pH, porosity, permeability, and reinforcement corrosion. A service-life criterion is proposed based on the time required for the chloride concentration at the reinforcement depth to exceed a critical depassivation threshold, followed by corrosion-induced cracking.
Khaled Aldhufri· Zenodo (CERN European Organi...· 0 citations
Cracking is the dominant serviceability and durability pathway in reinforced concrete because it accelerates the ingress of water, chlorides, sulfates, carbon dioxide, and other aggressive species toward the cement matrix and steel reinforcement. Self-healing concrete (SHC) seeks to convert this passive material into an autonomous repair system. This paper examines two technologically mature autonomous routes: bacterial microbially induced calcium-carbonate precipitation (MICP) and microcapsule-based delivery of mineral or polymeric healing agents. The study develops a coupled chemo–hydro–mechanical framework in which crack opening, fluid transport, bacterial metabolism, carbonate speciation, mineral precipitation, capsule rupture, agent diffusion, and damage recovery are represented by governing equations. A reaction–diffusion–precipitation model is proposed for bacterial healing, while a fracture-triggered release model is formulated for microcapsules. The resulting crack-closure efficiency is linked to permeability, stiffness recovery, corrosion-risk reduction, and life-cycle cost. The analysis indicates that bacterial systems are attractive where crack widths are small, moisture is intermittently available, and long service lives justify biological protection and nutrient design. Microcapsules provide faster and more controllable release but introduce finite healing inventory, interface defects, and possible strength penalties. For megaprojects, the rational strategy is not indiscriminate replacement of conventional concrete, but a reliability-based hybrid deployment in exposure-critical zones, supported by probabilistic quality control, digital monitoring, and life-cycle costing. The equations presented are a research-grade constitutive framework rather than a universal calibration; site-specific parameters must be identified through fracture, permeability, durability, and long-term viability testing.
Khaled Aldhufri· Zenodo (CERN European Organi...· 0 citations
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