Low-heat Portland cement and ground granulated blast furnace slag are widely used for the preparation of hydraulic concrete. Nevertheless, the effect and mechanism of corrosion on low-heat Portland cement paste mixed with ground granulated blast furnace slag need to be further explored. This paper investigated the impact of ground granulated blast furnace slag on the calcium leaching of low-heat Portland cement paste by evaluating its mass loss, porosity, leaching depth, compressive strength, and Vickers hardness, and comparing it with the leaching performance of ordinary Portland cement paste. Furthermore, the phase composition and morphology of low-heat Portland cement paste containing ground granulated blast furnace slag were analyzed by X-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy. The results indicate that, after 180 days of soaking in ammonium chloride solution, the mass loss rate, growth rate of porosity, leaching depth, and compressive strength loss rate of low-heat Portland cement paste were 8.0%, 43.6%, 9.1 mm, and 27.7%, respectively, while those of ordinary Portland cement paste were 7.4%, 37.8%, 8.4 mm, and 30.1%, indicating that low-heat Portland cement paste is slightly more damaging than ordinary Portland cement. The addition of ground granulated blast furnace slag could significantly improve the leaching resistance of low-heat Portland cement. For instance, after adding 20% ground granulated blast furnace slag, the above test values were 2.4%, 28.5%, 5.6 mm, and 20.8%, respectively. The reason for this is that ground granulated blast furnace slag has the potential to reduce the porosity of low-heat Portland cement paste, and it can also undergo the secondary hydration reaction with its hydration product Ca(OH)₂ to enhance the paste structure. Considering the cost performance, the suitable dosage of low-heat Portland cement paste for satisfactory leaching resistance is about 20%.

Geotextile bags are widely used in revetment engineering due to their simple fabrication and cost-effectiveness. However, prolonged exposure to natural environments can lead to aging and damage, compromising their performance. To enhance the durability of geotextile bags in practical applications, this study conducted microscopic examinations and strength tests, employing a slurry spraying method to form a protective surface layer. Adhesion tests and orthogonal experiments were performed to evaluate the impact of spraying parameters on performance. The optimal parameter combination was determined through range analysis, variance analysis, and projection pursuit regression (PPR) analysis, with the durability improvement verified by accelerated aging tests. Results demonstrated that sediment significantly reinforced the internal fibers and mechanical properties of the geotextile. Artificial slurry spraying effectively adhered to the geotextile surface, with clay slurry exhibiting the strongest adhesion. By integrating range analysis, variance analysis, and PPR analysis, the key influencing factors were identified as spraying thickness, geotextile thickness, and clay content. The optimal parameter combination was selected for accelerated aging tests and electron microscopy observation, revealing that the spraying treatment significantly improved the geotextile’s strength retention rate, delayed performance degradation under UV and high-temperature conditions, and protected the fiber structure. These findings provide valuable insights in terms of enhancing the durability of geotextile bags.