How to Verify the Carbonation Resistance of a Manufacturer's GRC Products? Testing Methods and Practical Guide

Carbonation resistance is a core indicator of GRC product durability, directly affecting the service life of components in atmospheric environments. Especially in environments such as industrial pollution and acid rain, insufficient carbonation resistance can easily lead to strength loss and surface powdering. Mastering scientific verification methods is key to selecting a quality GRC manufacturer. Drawing on 28 years of industry experience, Qinglong summarizes the core verification paths for carbonation resistance.

1. Core Testing Standards and Test Methods

Verifying carbonation resistance requires following industry standards, with the core basis being the "Glass Fibre Reinforced Cement (GRC) Decorative Products" JC/T 940-2022, which specifies the testing methods and indicator requirements for GRC carbonation depth. Laboratory testing adopts the accelerated carbonation test method: GRC specimens are placed in a carbonation chamber with a controlled carbon dioxide concentration of (20±3)%, temperature of (20±2)°C and relative humidity of (70±5)%. After 28 days of curing, the carbonation depth is measured using the phenolphthalein indicator titration method; quality GRC should have a carbonation depth of ≤1.0mm. Qinglong's provincial-level R&D center is equipped with a full set of testing equipment and can complete carbonation resistance tests in accordance with the standard, ensuring products meet requirements. For example, the GRC imitation stone components for the Dongting Lake Museum showed a measured carbonation depth of only 0.5mm.

2. Manufacturer Qualifications and Past Project Verification

The manufacturer's technical strength and past projects are indirect proof of carbonation resistance, so relevant qualifications and project practice should be carefully checked. Give priority to manufacturers that have participated in drafting carbonation-related standards—for example, Qinglong participated in formulating the "Technical Standard for Building Application of Glass Fibre Reinforced Cement (GRC)", demonstrating deep technical accumulation. Review the manufacturer's carbonation resistance test reports, which should be issued by authoritative third-party institutions and should include test parameters, process data and result analysis—avoid vague statements. Examine past projects in similar environments, such as industrial plants and coastal areas, to understand the service life and carbonation of GRC components. In the Panzhihua Third-Front construction project in Sichuan, Qinglong's GRC components showed no obvious carbonation or powdering after many years of use, verifying the product's carbonation resistance.

3. Raw Material and Production Process Verification

Carbonation resistance is closely related to raw materials and production processes, and can be indirectly verified by checking them. Regarding raw materials, low-alkali Portland cement with an alkali content of ≤0.6% should be selected, and active admixtures such as silica fume and fly ash can be used to improve density and enhance carbonation resistance. Qinglong uses high-grade low-alkali cement and quality admixtures to guarantee carbonation resistance at the source. Regarding production processes, a low water-cement ratio (≤0.45) and adequate curing are key: a low water-cement ratio reduces porosity, and curing at constant temperature and humidity ensures full cement hydration. Qinglong controls the water-cement ratio through automated metering and uses dedicated curing kilns to ensure curing quality—these process details directly affect carbonation resistance.

4. On-Site Sampling Tests and Comparative Verification

For major projects, on-site sampling tests can be adopted to ensure actual product performance. Randomly sample GRC specimens during the manufacturer's production process and send them to a third-party institution for carbonation resistance testing; the results should be consistent with the reports provided by the manufacturer. When conditions permit, small specimens can be made for outdoor exposure tests to simulate the project's actual environment, with carbonation depth tested periodically. In an industrial project, Qinglong verified through a 1-year outdoor exposure test that the GRC carbonation depth grows slowly and performance remains stable. Meanwhile, you can compare the carbonation resistance test data of different manufacturers and make a comprehensive evaluation combining price and other performance indicators, avoiding focusing on a single indicator, so as to select a product with excellent overall performance and ensure long-term project stability.