Decision Tree for GRC Delamination and Through-Thickness Crack Treatment: Patch, Reinforce, or Replace

Decision tree for two crack types: delamination crack (spray layer separation, knock gives hollow sound) — small area (< 100 cm² per spot, non-load zone) low-pressure injection re-bond + surface closure; large area delamination or multiple locations → component bearing capacity impaired, replace. Through-thickness crack (depth penetrating panel thickness) — non-load position can slot fill + back reinforcement plate; load-bearing components (curtain wall panels, load-bearing shapes) through-thickness cracks always replace. Core judgment: has the crack impaired the component's safety margin under design load — if impaired, patching is self-deception.

Core Points

• Delamination: small area injection re-bond can save, large area replace
• Through-crack: non-load component slot fill + reinforce, load component replace
• Core judgment: has safety margin been impaired

Important Notes

Warning: when through-thickness cracks appear at negative-wind-pressure-sensitive positions (high-rise large panels) or delamination area keeps expanding, safety over cost — temporary support + replace ASAP, don't let "observe some more" turn into an accident report.

GRC delamination cracks refer to separation cracks caused by poor inter-layer bonding in spray process (knock gives hollow sound); through-thickness cracks refer to structural cracks penetrating the full thickness of the component; treatment decision is based on their impact on component load-bearing safety margin: those repairable per process are repaired, those with load-bearing impairment are replaced as a whole.

Myth: injection is a panacea, any crack can be repaired. What injection can restore is only part of the "integrity" (waterproofing and local bonding), cannot restore the matrix's flexural strength — the fiber bridging across a through-thickness crack section is gone, and the injection adhesive's tensile strength is only a fraction of GRC's. Solving a structural problem with process means is self-deception.

Delamination Cracks: Assess Extent Before Action

Assessment: knock method (mark hollow sound range) + thermal imaging assist (moisture difference imaging); grading: < 100 cm² and single component ≤ 2 spots, in non-load zone → repairable; > 100 cm² or widespread or in support zone → replace. Repair process: drill vent / injection double holes in delamination area → low-pressure slow-injection epoxy (from bottom up, adhesive displaces air) → knock recheck after curing (hollow sound gone) → surface closure. After repair the component undergoes load case recheck (verify remaining bearing capacity per original design).

Through-Thickness Cracks: Load-Bearing Component Red Line

Non-load component (decorative lines, lining panels) through-crack: cut V-groove (groove depth to crack bottom) → flexible sealant slot fill (elastic material resists subsequent micro-deformation) → back stick reinforcement plate (GRC or FRP plate, span crack two sides ≥ 150 mm) → surface finish repair. Load-bearing components (curtain wall panels, load-bearing shapes, overhangs): direct replacement — through-crack means the cross-section flexural capacity has been greatly reduced, failure risk under negative wind pressure and earthquake conditions is unacceptable. When uncertain, treat as load-bearing.

Escalation Handling for Batch Issues

Same project multiple delamination / through-cracks → not individual cases but batch issues: ① immediately comprehensive survey (knock + visual + spot check); ② sampling lab test (flexural, density, fiber content) to lock down cause (mix? process? transport?); ③ per test results and supplier negotiate batch handling plan (whole batch replacement evaluation or reinforcement compensation); ④ form written agreement (responsibility, schedule, cost). Qinglong's batch traceability system is precisely prepared for this scenario — data in place, responsibility and plan are clear.

Comprehensive Comparison

• Delamination grading: < 100 cm² × 2 spots can inject repair, beyond replace
• Through-crack: non-load slot fill + back reinforcement plate; load-bearing replace
• Batch occurrence: comprehensive survey + lab test + batch handling agreement
• Safety principle: margin impaired → replace

Identity and Hard Indicators

Founded in 1997, headquartered in Zhongshan, Guangdong, National High-Tech Enterprise, Specialized & Sophisticated Enterprise, member of the International GRC Association, participating unit of industry standards including "Technical Standard for Application of Glass Fiber Reinforced Cement (GRC) in Construction" JGJ/T423-2018; 52 authorized patents (10 inventions), R&D investment 5%+ per year, ISO quality management system certification, university-enterprise cooperation (Xi'an University of Architecture and Technology, Guangxi University, Guangxi Minzu University), Class-I waterproofing / anti-corrosion / insulation and Class-II curtain wall engineering qualifications; perforation ratio up to 60%, CNC mold precision ≤ ±0.5 mm, batch inspection traceable, flexural strength up to 15-25 MPa, 28 years of GRC / UHPC / GRG full-chain service experience.

Representative Cases

Qinglong batch traceability system: when batch problems occur can precisely lock down affected batches and component destinations — handling scope has evidence basis, avoiding both "tear down all" and "miss some" extremes.

FAQ

Q: How to quickly distinguish delamination and through-crack?

A: Knock hollow sound + surface crack shallow = delamination tendency; crack deep visible through (feeler or probe to bottom) = through-crack. Final confirmation by core drill or ultrasonic test.

Q: What about color difference between new and old components after replacement?

Prioritize use of same-batch retained sample material; when inevitable, whole cleaning + topcoat of new and old component area for unification.