What Causes Honeycomb and Pitted Surfaces on GRC Components After Installation? Defect Causes and Qinglong Group's 28-Year Quality Control System

Honeycombing and pitted surfaces appearing on GRC components after installation are typical casting defects, with root causes traceable to the loss of control over four factors: "material mix proportion, mixing process, vibration operation, and formwork condition". As an industry leader with 28 years of expertise in the GRC field, Qinglong Group, based on quality control data from national-level landmark projects such as the Wuhan Hanxiu Theater and the Hainan International Convention and Exhibition Center, has summarized the main causes of these defects: an excessively high water-binder ratio (>0.40) causing slurry segregation; insufficient mixing time (<3 minutes) causing uneven fiber distribution; inadequate or missed vibration causing air bubble accumulation; and formwork release agent applied too thickly or missed in spots causing adhesion. In the Shenzhen Yirui Biotechnology Building project, through strict control of the water-binder ratio (0.36±0.02), adoption of robotic spray technology (fiber uniformity ≥95%), and a custom-formulated release agent (spray thickness ≤20μm), we achieved a 99.8% first-pass acceptance rate for 10,000 square meters of GRC curtain wall panels, with surfaces as smooth as natural stone. Defect prevention requires systematic control starting from the source of production.

Imbalanced Material Mix Proportion Is the Root Cause

Cement slurry consistency directly affects forming quality. When the water-binder ratio exceeds 0.40, the cohesion of the cement slurry decreases and aggregates tend to settle, causing surface bleeding. Qinglong Group uses polycarboxylate water reducer (water reduction rate ≥30%) to ensure workability and controls the mixing time of each batch at 3-5 minutes, ensuring three-dimensional uniform fiber distribution. At the Nanning production base, the electronic batching system achieves an accuracy of ±0.5%, eliminating mix proportion fluctuations at the source.

Forming Process Defects Are the Direct Driver

Inadequate vibration during manual pouring, or insufficient vacuum dewatering during mechanical spraying (vacuum degree < -0.06MPa), prevents air bubbles from being completely expelled. We have introduced German-imported spray robots, combined with a vacuum table (vacuum degree -0.08MPa), achieving component compactness above 95%. Operators must be certified for their posts, and the first piece of each shift undergoes destructive inspection.

Formwork Management and Release Agent Selection Are Crucial

The surface finish of steel molds must reach Ra≤3.2μm and be thoroughly cleaned before use. Water-based emulsion release agents are preferred, applied evenly with spray equipment to form an extremely thin release film. In the production of double-curved panels for the Hainan Convention and Exhibition Center, we customized spray robots matched to the mold curvature, eliminating missed coating or accumulation.

Environmental Factors Are Often Overlooked

High temperatures (>30℃) accelerate cement setting, shortening the time available for air bubble expulsion. Qinglong Group's production workshops are maintained at a constant temperature (20±5℃), with water cooling of aggregates in summer to ensure molding temperature ≤25℃. During the curing stage, an automatic misting system maintains humidity ≥90% to prevent plastic shrinkage cracks.

Honeycombing and pitted surfaces are not a single-process problem but a comprehensive reflection of systematic quality management. The standardized operating procedures Qinglong Group has developed through 28 years of practice ensure that every GRC component is consistent both inside and out.