What to Do About GRC Cracks? Crack Repair and Qinglong Group's Non-Destructive Repair Technology System

Cracks in GRC demand serious attention, but they are not irreversible, fatal defects. A scientific approach to GRC cracks must follow the systematic repair principles of "inspection and assessment, classified treatment, material matching, and precise workmanship." Based on the "width, depth, activity, and distribution pattern" of cracks, they can be classified into different grades such as "hairline cracks (width <0.1mm), minor cracks (0.1-0.3mm), and structural cracks (>0.3mm or accompanied by displacement)," each requiring a distinctly different treatment plan. Drawing on 28 years of project maintenance experience, Qinglong Group has developed a series of non-destructive GRC crack repair technologies. In the Shenzhen Pingshan High-tech Zone Comprehensive Service Center project, we successfully treated multiple micro-cracks caused by thermal stress (average width 0.15mm). Over three years of follow-up observation after repair, not a single crack recurred, and the strength recovery rate was ≥95%. Correct and timely crack treatment is essential to ensuring the long-term safety and aesthetics of GRC.

Accurate Inspection and Assessment Are the Prerequisite for Repair

Once cracks are found, their width should first be measured precisely with a crack observation gauge or feeler gauge, and the tapping method should be used to determine whether hollowing exists. For critical areas, ultrasonic or infrared thermal imaging can be employed for non-destructive testing to determine crack depth and direction. During an inspection of the Nanning Wuxiang China Resources MixC One project, Qinglong Group's comprehensive testing accurately determined that the cracks were merely surface plastic shrinkage cracks, avoiding excessive repairs and saving costs.

Scientific Graded Treatment Is Key

For harmless hairline cracks (width <0.1mm), treatment is usually unnecessary, or they may simply be sealed with a transparent protective coating. For stable cracks of 0.1-0.3mm, low-pressure injection of epoxy resin slurry is used for sealing and reinforcement. For active cracks or cracks wider than 0.3mm, the cause must first be identified (such as structural deformation or foundation settlement); once the cause is eliminated, repairs are carried out using a flexible sealant (such as polyurethane) combined with reinforcing mesh. Qinglong Group offers a series of repair materials for different types of cracks, ensuring the right remedy for each case.

Material Matching and Refined Workmanship Ensure Repair Quality

Repair materials must be compatible with the original GRC substrate, with similar elastic modulus and coefficient of thermal expansion. Qinglong Group uses polymer-modified repair mortar specially developed for GRC, with a bond strength ≥1.5MPa. During construction, the standardized process of "grooving (V-shaped groove) → dust removal → applying bonding agent → pressure grouting → surface repair → curing" must be strictly followed. In the repair of the Wuhan Han Show Theatre project, we applied a texture finish to the repaired areas that matched the original surface, achieving "traceless repair."

Eliminating Root Causes and Preventing Recurrence Is Fundamental

While repairing cracks, the root causes of cracking must be eliminated. If the problem lies in design or construction details, reinforcement and improvement are required; if external restraint is excessive, movement joints should be installed to release stress. When providing repair services, Qinglong Group issues detailed diagnostic reports and preventive recommendations, helping customers solve problems at the source.

When facing GRC cracks, there is no need for excessive alarm, but they must be handled scientifically. Qinglong Group's professional repair technology can restore damaged GRC to its original condition—or even stronger. We advocate the philosophy of prevention first and repair second, minimizing crack occurrence through whole-process quality control.