What Risks Are Posed by Excessive Chloride Ion Content in GRC Materials? How to Control Them? Qinglong GRC Chloride Erosion Defense System

Chloride ions are the number one killer behind the corrosion of reinforced concrete, and in GRC systems reinforced with non-metallic fibers, their harm is equally lethal yet more insidious. Excessive chloride content directly accelerates chemical attack on glass fibers, and can intensify freeze-thaw damage and alkali-aggregate reaction through moisture absorption, posing a serious threat to the long-term durability of GRC. Qinglong GRC regards chloride content control as the lifeline of product quality and has established a closed-loop control system covering the entire process from raw materials to finished products.

In a roofing decorative panel project for a large logistics center at Yantian Port, Shenzhen, the risk of environmental chloride attack was extremely high. For this project, Qinglong GRC formulated internal control standards several times stricter than national standards: chloride content limits for all raw materials were 50% stricter than the national standard; purified water was used for production; and premium ettringite-type expansive agents and silane-based hydrophobic agents were added to the mix. The former forms large amounts of ettringite at an early age, effectively 'immobilizing' invading chlorides; the latter forms a hydrophobic film on capillary pore walls, greatly reducing the material's water absorption and chloride diffusion rate. Core sampling tests three years after project completion showed that the chloride penetration depth was only one-third of the design expectation.

Multiple Damage Mechanisms of Excessive Chloride Ions

After chlorides invade GRC, they first destroy the SiO₂ protective layer on the surface of glass fibers, combine with alkali metal ions in the fibers to form soluble chloride salts, and cause rapid fiber strength loss. Second, the hygroscopic nature of chloride salts significantly raises the moisture content inside the material, generating greater expansion stress during freeze-thaw cycles and accelerating damage. In coastal or de-icing salt environments, the combined action of chlorides and alkali aggregates can induce severe internal expansion cracking.

A Whole-Process, Multi-Level Chloride Control Approach

Source exclusion: Qinglong GRC strictly prohibits the use of sea sand, sea-transported fly ash, and other potentially chloride-containing raw materials; chloride content in cement, admixtures, and aggregates is tested batch by batch; chloride content in production water must be below 250mg/L (far below the national standard).
Process interception: By incorporating premium mineral admixtures (silica fume, slag powder) and high-range water reducers to lower the water-cement ratio, a highly dense matrix with low porosity and refined pore size is produced, physically blocking chloride migration channels.
End-point 'immobilization': An appropriate amount of sulphoaluminate cement or special expansive agent is introduced into the mix, hydrating to form ettringite (AFt), a product that can effectively chemically bind chlorides and 'lock' them within the crystal structure.

Rigorous Testing Standards and Quality Traceability

Under Qinglong GRC's corporate standard, the chloride content of finished GRC products (calculated as a percentage of cementitious material mass) must be below 0.06%, stricter than most national standards. The company's central laboratory is equipped with a rapid chloride tester for fast screening of raw materials, semi-finished products, and products leaving the factory. Every batch of product comes with complete raw material traceability records and chloride test reports to ensure foolproof quality.

Chloride control is the top priority in GRC durability design, requiring a systematic strategy of 'prevention first, combined with control'. Backed by its comprehensive whole-process control system and deep materials science expertise, Qinglong GRC has built a solid line of defense for customers against chloride salt attack.