Investigating the role and mechanism of multi-component corrosion inhibitors in anti-corrosion of grouting anchor cables

• This study presents the first application of multi-component corrosion inhibitors to mitigate corrosion in anchor cables. • A strength degradation model for anchor cables is developed based on the inhibitors’ anti-corrosion efficiency and the cables’ corrosion rate. • Theoretical analysis confirms that multi-component corrosion inhibitors afford effective corrosion protection for anchor cables in deep coal mines. The harsh mining environment in deep coal mines severely restricts the long-term safety and stability of support systems. Anchor cable support is one of the critical countermeasures to defend against wall rock dynamic hazards. Introducing corrosion inhibitors into ordinary silicate-based materials (grouting materials) represents a novel and potentially transformative approach for protecting anchor cables from corrosion. The mechanism of action and protective effects of corrosion inhibitors were analyzed using strength tests, electrochemical measurements, microscopic morphological analysis, numerical simulation, and theoretical calculations. The research results demonstrate several important and original findings: Trisodium phosphate (TSP) and sodium monofluorophosphate (MFP) retard the setting of grouting materials, disodium hydrogen phosphate (DHP) has negligible impact, whereas chromic oxide (Cr₂O₃) accelerates early strength development. By precisely controlling the type and mass fraction ( ω ) of corrosion inhibitors, their effects on the mechanical strength of grouting materials can be effectively managed, allowing performance optimization without compromising structural integrity. TSP, MFP, DHP, and Cr₂O₃ reduce the corrosion current density ( i corr ) on anchor cable surfaces, with anti-corrosion performance positively correlated to ω. The addition of MFP and ZnO to Cr₂O₃ decreases the required dosage while simultaneously improving anti-corrosion efficiency ( γ ). All four inhibitors increase the impedance of anchor cable specimens, yet the corrosion process remains dominated by charge transfer mechanisms. When MFP is combined with Cr₂O₃, corrosion resistance is primarily determined by the MFP dosage, while excessive ZnO addition to Cr₂O₃ reduces γ . A deterioration model was established linking anchor cable load-bearing capacity with γ and time-dependent corrosion rate ( I corr ( t )), revealing that corrosion inhibitors can extend anchor cable service life from 1.5 years to 3.9 years (under an 80 % failure standard). This demonstrates a substantial enhancement in long-term durability under deep mining conditions.