Evaluation of groundwater corrosivity in the Liaohe River delta region

Groundwater in the Liaohe River delta in Liaoning, NE China exhibits a complex chemical composition, posing significant corrosion risks to underground engineering materials. Based on water quality data from the delta region and guided by the Code for Geotechnical Engineering Investigation(China National Standard No. GB 50021—2001), the characteristics of corrosivity by the shallow groundwater in the delta region on local concrete and steel reinforcement. Results indicate that the corrosiveness of groundwater to concrete in the study area was primarily controlled by sulfate (SO₄²⁻, up to 2 353.47 mg/L), total dissolved solids (TDS; up to 52 444.25 mg/L), and environmental pH (ranging from 7.0 to 8.1). In the Type II Environment of China, groundwater with SO₄²⁻ concentrations between 300 and 1500 mg/L is classified as weakly corrosive, thus 25% of the samples felt into this category. In some local areas (stations #18 and #20), where SO₄²⁻ concentrations exceeded 1500 mg/L and TDS level was above 50 000 mg/L, the groundwater was bracketed into moderately corrosive, representing 10% of the samples. Additionally, the combined effect of erosive CO₂ (＜1.60 mg/L) and a near-neutral microenvironment (pH ≈ 7.1) within weakly permeable strata further intensified the corrosion to the concrete. The synergistic effects of Cl⁻ (up to 29 246.25 mg/L) and SO₄²⁻ (up to 2 353.47 mg/L) lead to moderate corrosion to the steel reinforcement in local areas (e.g., Sites #18 and #20, 15% of the total area), and the local weakly acidic microenvironment (pH≈7.1) further accelerated the degradation. To address the spatial distribution of corrosion risks, zoned prevention strategies were proposed, including the use of sulfate-resistant cement-based composite materials, composite anti-corrosion techniques, high-density construction processes, and enhanced low-temperature wet curing combined with protective coatings. The findings provided a theoretical support for durability design and corrosion prevention in underground engineering projects in similar coastal regions.