How to Test the Chloride Ion Content of GRC Panels?

Testing the chloride ion content of GRC panels is an important means of evaluating their durability and requires scientific sampling and testing methods. In accordance with the JGJ/T423 standard, Qinglong Group has established a complete chloride ion testing procedure.

Sampling is a key step in testing. Powder samples are drilled from different parts of the panel at three depth levels: 0-5mm, 5-15mm, and 15-25mm. Qinglong Group requires at least 3 samples per batch, each weighing no less than 100g. After sampling, the samples must be immediately sealed and stored to prevent chloride ion volatilization.

Testing is performed using the silver nitrate titration method. The samples are crushed and sieved through a 0.15mm sieve, then soaked in distilled water for 24 hours and filtered. Take 50ml of the filtrate, add potassium chromate indicator, and titrate with a 0.01mol/L silver nitrate standard solution until a brick-red endpoint is reached. The chloride ion content is calculated from the volume of silver nitrate consumed. Qinglong Group's internal standard requires the chloride ion content to not exceed 0.06% of the mass of cementitious materials.

Rapid testing is used for on-site quality control. With a rapid chloride ion tester, preliminary results can be obtained within 30 minutes. Although the accuracy is slightly lower, it meets the needs of on-site quality control. This rapid testing method provides timely feedback for the production process.