Time-dependent degradation behaviour of graphene oxide-modified ternary concrete under sulfuric acid attack

Severe sulfuric acid (H 2 SO 4 ) exposure accelerates deterioration of concrete sewer infrastructure, yet the mechanisms by which graphene oxide modifies acid transport and degradation kinetics in ternary blended systems remain insufficiently quantified. This study develops an experimental–numerical framework to assess graphene oxide–modified ternary blended nano-concrete composites (GO-TBNCCs) incorporating 20% fly ash (FA), 20–40% ground granulated blast-furnace slag (GGBFS), and poly-functionalised graphene oxide (p-GO, 0–0.0639 wt%) under highly aggressive H 2 SO 4 exposure at pH 1.00. Twelve mixes were immersed over a one-year exposure period, and degradation depth, residual strength, degradation rate, and surface pH evolution were experimentally evaluated to assess acid-resistance performance (ARP). A diffusion-based numerical framework was then developed to estimate apparent diffusion coefficients and predict long-term degradation progression. The results reveal that p-GO incorporation not only improves ARP but also modifies the degradation process by restricting ion ingress and reducing acid transport. The optimal mix (C-G3) achieved approximately 143% higher compressive strength, 89% lower degradation depth, and a degradation rate nearly nine times lower than the control, while maintaining a surface pH of at least 8.5. The apparent diffusion coefficient decreased with increasing p-GO dosage, reaching a minimum of 7.24 × 10⁻ 12 m 2 /s, approximately 79% lower than the control. The proposed degradation model showed strong agreement with experimental results, capturing degradation depth evolution with R 2 values exceeding 0.98. Long-term projections estimated approximately 13 mm degradation for C-G3 after 50 years, below the typical 40 mm cover threshold for reinforcement protection. These findings establish an experimental–numerical basis for relating p-GO-induced transport resistance to long-term degradation prediction, supporting GO-TBNCC as promising acid-resistant cementitious materials for sewer and other acid-exposed infrastructure.