An electrochemical method for reinforcing marble stone: The deposition of aluminium phosphate materials

• Aluminum phosphate deposited on marble surface, forming a continuous protective coating. • Aluminum phosphate deposited interior of marble and refined pore structure . • Electrochemical deposition reinforcement method greatly improved acid resistance of marble. In recent years, aluminium phosphate has demonstrated promising results in reinforcing and protecting marble stone relics. However, there is still room for improvement in terms of permeability and coating continuity. In this study, an electrochemical deposition method was utilized to reinforce simulated weathered marble, employing diammonium phosphate as the cathodic reaction raw material and aluminium chloride as the anodic reaction raw material. The protective mechanism of this method was analyzed using SEM-EDS, and the effectiveness and compatibility were evaluated by testing wettability, surface free energy, surface roughness, porosity, acid corrosion resistance, water vapor transmission rate and color difference. The results revealed that, uniform deposition of aluminium phosphate led to a reduction in the surface free energy and porosity, but an increase in water droplet penetration time of the reinforced marble. These changes significantly improved the acid erosion resistance of the marble. Furthermore, this reinforcement method can maintain good compatibility of the reinforced marble in terms of color and breathability. The electrochemical deposition method utilizing diammonium hydrogen phosphate and aluminium chloride as the main materials exhibits substantial potential in weathering-resistant reinforcement of marble stone relics.