During the landfilling and resource utilization of solidified soil, it is inevitable that the material will be influenced by the surrounding water environment. Processes such as soaking and infiltration of both clean water and contaminated liquids can have an impact. This paper investigates the strength and structural stability of soil contaminated with a high concentration of lead or copper that has been solidified with red mud-carbide slag-phosphogypsum (RCP-Pb or RCP-Cu, respectively) in strongly acidic water, weakly acidic water, and pure water, as well as in two different modes of soaking and infiltration. The unconfined compressive strength, apparent and microscopic morphology, mineral composition, and functional groups of solidified soil before and after the action of different water solutions were compared, and the water and acid resistance of solidified soil was comprehensively analyzed. The results indicate that under the influence of a strongly acidic water environment, the strength of RCP-Pb and RCP-Cu can decrease by up to 26.4% and 18.5%, respectively, compared to the standard solidified specimens. Conversely, in a weakly acidic environment, the strength of the specimens can increase by a maximum of 21.1% and 32.8%, respectively. Under the two different water environment modes of action, RCP-Pb exhibits a greater increase in strength (39.8%) under soaking conditions, while RCP-Cu shows a greater increase (44.4%) under water infiltration. Based on the microscopic images, the pore counts in specimens in weakly acidic and pure water environments are greater than those in standard solidified specimens, while the porosity is less than that in standard solidified specimens. The surface of the particles exhibited increased roughness. A noticeable finding is that, under the infiltration of a strongly acidic water environment, the porosity of RCP-Pb increases to 20.22%, and the pore counts of RCP-Cu rise to 534. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses revealed that as the acidity of the water environment increased, the CaCO3 content significantly decreased. However, hydration products such as calcium silicate hydrate (C-S-H), calcium aluminate hydrate (C-A-H), calcium aluminosilicate hydrate (C-A-S-H), and ettringite (AFt) did not show significant differences. Consequently, the specimens maintained a stable strength and structure even under such a water environment.

The long-distance oil pipeline in the R-K region of Chad has experienced frequent failures of heat-shrink sleeves, significantly impacting normal production in the oilfield. Therefore, a systematic study of the soil corrosion behaviour of pipelines after heat-shrink sleeve damage is essential before implementing targeted anti-corrosion measures to prevent and control soil corrosion. Through sample composition analysis, electrochemical testing, and immersion experiments on the crude oil pipeline in the specified area of Chad, as well as morphology and composition analysis of the corrosion products formed on the pipeline, the main cause of corrosion failure was inferred to be the high content of CO2 and Cl? in the soil, as their synergistic effect induces pitting corrosion on the pipeline. Furthermore, the high humidity and abundant rainfall in the Chad region increase the corrosion risk. The primary soil corrosion products are Fe2O3 and FeCO3, along with small amounts of Fe3O4, FeCl (OH), and CaCO3. The average corrosion rate along the pipeline soil line ranges from 0.10 to 0.13 mm a-1.

In the construction of traffic engineering, a large amount of waste soils was generated. These soils have poor engineering properties, cannot be used as subgrade fill, so they were solidified treatment, commonly used cement curing agent have adverse effects on the environment. One-part geopolymer (OPG), as a green and new type of soil stabilizer, not only provides a new idea for the solidification of engineering waste, but also offers an effective way for the disposal of industrial solid waste, and reduces the consumption of cement. In order to evaluate the durability of geopolymer solidified soil, in this paper, with fly ash (FA) and ground granulated blast furnace slag (GGBS) as raw materials, solid NaOH and Na2SiO3 2 SiO 3 as solid alkali-activator to prepare OPG, which was used as a solidifier to solidify the waste dredged silt to produce one-part geopolymer-solidified soil (OPGSS). The variation patterns of mass, unconfined compression strength (UCS) and elasticity modulus of OPGSS with attack time under 0%, 5% and 10% Na2SO4 2 SO 4 solutions were investigated. The changes in the phase composition, micro- morphology and pore size distribution of OPGSS were characterized by XRD, SEM-EDS and nuclear magnetic resonance (NMR). The results showed that: Under both 5% and 10% Na2SO4 2 SO 4 solutions, the UCS of OPGSS decreased in two stages with attack time, and the number of large pores and total pores of OPGSS increased in two stages. The inflection points appeared on day 8 under 5% Na2SO4 2 SO 4 solution; the inflection points appeared on day 5 under 10% Na2SO4 2 SO 4 solution. This was mainly due to the expansion of corrosion products formed by OPGSS under Na2SO4 2 SO 4 attack, which destroyed the microstructure of OPGSS and led to a reduction in the UCS of the OPGSS.