What Protective Measures Do GRC Exterior Walls in Acid Rain Regions Need? Acid-Resistant Design and Qinglong Group's Enhanced Protection Strategies

In industrial cities with frequent acid rain or in specific climate zones, GRC exterior walls face long-term attack from corrosive media such as H⁺ ions and SO₄²⁻, which may lead to corrosion of the surface cement paste, aggravated efflorescence, and strength deterioration. For acid rain environments, Qinglong Group has formulated a systematic reinforcement and protection strategy of “improving matrix density, strengthening surface protection, and optimizing drainage detailing”. First, in terms of material mix proportions, we use low-alkali sulphoaluminate cement or ordinary Portland cement blended with a large amount of mineral admixtures (such as silica fume and slag) to reduce the Ca(OH)₂ content in the system and improve acid resistance. At the same time, we strictly control the water-cement ratio to produce a highly dense, low-porosity GRC matrix, slowing the penetration of acid liquids at the source.

Surface protection is the first and most important line of defense. In acid rain areas, we require as mandatory that GRC panels undergo comprehensive surface sealing treatment. The best solution is to apply a high-quality fluorocarbon coating, whose dense paint film can effectively isolate acid liquids from contact with the GRC matrix. In addition, periodically applying (with the recommended cycle shortened to 3–5 years) a penetrating silane protective agent, which forms a hydrophobic layer on the capillary pore walls, can also significantly reduce the adsorption and penetration of acid liquids. In a project located in an acid rain zone in Chongqing, we applied dual protection of “fluorocarbon topcoat + silane base treatment” to the GRC panels. After 8 years of use, inspection showed that the surface condition was significantly better than comparison samples without reinforced protection.

The “rapid drainage” principle in detailing is equally critical. Reasonable drainage slopes must be designed to ensure that no water accumulates on panel surfaces and that joints drain smoothly, allowing acid rain to be drained away quickly and reducing its contact time with material surfaces. Qinglong Group recommends that GRC exterior walls in acid rain areas should have an appropriately increased cleaning frequency, using neutral detergents to promptly wash away acid corrosion residues on the surface. Only through a four-pronged approach covering materials, coatings, detailing, and maintenance can GRC exterior walls remain durable and ever-new in acid rain environments.