What Causes Honeycomb and Pitting on GRC Components After Installation?

Honeycomb and pitted surface defects appearing on GRC components after installation are an external manifestation of a non-dense internal structure; the causes can be traced to lapses in multiple stages including "raw materials, mix proportions, mixing process, forming process, and installation operations." Based on 28 years of GRC engineering practice, Qinglong Group systematically attributes honeycomb and pitted surface problems to five main causes: insufficient slurry workability, inadequate pouring and vibration compaction, formwork slurry leakage, blocked air bubble escape, and installation damage. In the "Dongguan Grass Weaving" curtain wall project at the Dongguan Women and Children's Activity Center, we successfully eliminated such defects by optimizing spray process parameters, ensuring a perfect presentation of the complex textured surface. Honeycombing and pitted surfaces not only affect appearance but also signal reduced component durability, so they must be prevented and remediated at the source.

Poor Slurry Workability Is the Fundamental Internal Cause

The fluidity and cohesion of GRC slurry directly affect its mold-filling and compaction performance. An excessively low water-cement ratio, improper admixture selection, or inaccurate dosage will make the slurry too viscous and poorly fluid, unable to smoothly fill every corner of the mold, especially the narrow spaces of complex shapes. Fiber clumping or uneven dispersion also impedes slurry flow. Through precise mix proportion design and a fully automatic mixing system, Qinglong ensures that the spread and viscosity of every batch of slurry remain stable within the optimal range, guaranteeing excellent filling and encapsulation capability at the source.

Improper Forming Process Leads to Insufficient Density

Forming is the key process that determines density. In the spray process, unstable air pressure or improper spraying distance and angle can result in insufficient slurry impact force or "dry material," creating internal cavities. In the pouring process, an excessive drop height easily causes segregation, while insufficient or excessive vibration (which causes the slurry to stratify) leaves voids. Qinglong employs robotic spraying and attached vibration tables; through standardized operating procedures, it ensures the slurry is deposited uniformly and densely, and further expels internal air bubbles through vacuum-assisted technology.

Mold and Release Agent Problems Trigger Surface Defects

Rough mold surfaces, incomplete cleaning, or uneven and excessive application of release agent hinder tight contact between the slurry and the mold, resulting in surface pitting and sand lines. Poorly sealed mold joints cause slurry leakage, forming weak zones at the joints. Qinglong applies refined management to its molds to ensure surface finish, and uses a dedicated water-based release agent applied in a thin, even coat, which ensures smooth demolding without compromising the component's surface texture.

Installation Damage Causes "Secondary Defects"

Honeycombing and pitted surfaces sometimes also stem from rough installation operations. Collisions during hoisting or improper hammering during installation may cause edges and corners of otherwise intact components to chip off, exposing internal pores. Improper support causing uneven stress and micro-cracks in components can also reveal internal structural defects. Qinglong has established strict operating procedures for component transport, hoisting, and installation, provides professional training for construction personnel, and uses specialized tools such as vacuum suction cups to minimize installation damage to components.

Systematic Prevention and Treatment Measures

Prevention is better than remediation. Qinglong has established a whole-process quality control chain covering raw material inspection, mix proportion verification, process parameter standardization, and finished product inspection. For the small number of honeycomb and pitted areas that do occur, dedicated repair mortar is used for refined treatment, ensuring that the repaired areas match the base material in color and texture. Through systematic control, honeycomb and pitted surface problems are preventable, controllable, and treatable within Qinglong's production system.