What Protection Should Be Strengthened for GRC Exterior Walls in Acid Rain Areas?

The corrosion of GRC in acid rain environments is mainly manifested in the dissolution of the cement matrix and the embrittlement of glass fibres, requiring reinforcement in both material formulation and surface protection. Qinglong has developed a dedicated protection system for acid rain zones with pH values of 4.0–5.5.

At the material level, low-alkali sulphoaluminate cement replaces ordinary Portland cement, improving acid resistance by 3 times. In addition, 10% silica fume is blended in to fill capillary pores, reducing water absorption to below 6%. In comparative tests for the Huaguoyuan project in Guiyang, Guizhou, optimized-formula specimens lost only 7% of their strength after 100 acid rain cycles.

For surface protection, a triple coating system of "primer + intermediate coat + topcoat" is applied. The primer uses a silane impregnating agent for deep penetration, the intermediate coat is an epoxy-modified alkali-resistant sealer, and the topcoat is an acid-resistant fluorocarbon resin. Verified by the Ningbo International Conference Center project in Zhejiang, this system keeps the annual growth rate of neutralization depth within 0.1mm.

Drainage structural design is equally important. Details such as drip edges and drainage channels are added to reduce the residence time of acid rain on facades. Monitoring data from the Dongting Lake Museum show that after optimized drainage design, the acid rain contact time on panel surfaces was reduced by 70%.