Performance and mechanism of a dual-functional Cr2O3 additive for reinforcement and corrosion protection of deep mine grouting anchor cables

Deep underground coal mining faces severe challenges from the "three highs" environment (high ground stress, high temperature, and high salinity), which threatens the structural integrity of high-strength steel anchor cables. This study proposes the use of Chromium oxide (Cr 2 O 3 ) as a novel dual-functional additive to simultaneously enhance the mechanical strength of the grouting body and the corrosion resistance of anchor cables. Experimental results demonstrate that incorporating Cr 2 O 3 into M50 fast-setting Portland cement grout improves the 7-day compressive strength by over 40%. Electrochemical tests in simulated Zhaolou Mine groundwater reveal that a 2.0% Cr 2 O 3 dosage reduces the corrosion current density (I corr ) by 81% and shifts the free corrosion potential (E corr ) positively by 0.142 V, exhibiting significant anodic inhibition characteristics. To bridge the gap between laboratory tests and field applications, a 3D stress-electrochemical coupled numerical model was developed. The simulation predicts that the material loss of Cr 2 O 3 -modified cables is reduced by 99% after 1500 days of service compared to ordinary cables. The synergistic protection mechanism is primarily driven by the physical micro-filler and heterogeneous nucleation effects of Cr 2 O 3 particles, which significantly refine the matrix pore structure, synergized with the chemical formation of a dense, stable passive film on the steel surface. This work provides insight into mechanism of a dual-functional Cr 2 O 3 additive for ensuring the durability of roadway supports in deep-mine environments.