GRC Tender Technical Specifications Writing Guidelines: Material Parameters, Performance Indicators, and Testing Requirements Template

The five essential modules in a GRC technical specification document are: ① List of applicable standards and specifications (JGJ/T423-2018 as the main standard); ② Material parameters – AR alkali-resistant glass fiber content (spraying method ≥5%, zirconium content ≥16.5%), cement type, slab thickness and tolerances, and bulk density grade; ③ Performance indicators – design value of flexural strength (by strength grade), water absorption rate, wet-dry cycle and freeze-thaw cycle (by region); ④ Testing and witnessing – list of batch-specific testing items, witnessing sampling clauses, and rules for rejecting unqualified batches; ⑤ Surface finish – sealing clauses (color swatch benchmarks and acceptance methods). Incorrect or missing parameters are a technical loophole that allows low-priced, inferior parts to win bids.

Key points

1) Five modules: Standard list/Material parameters/Performance indicators/Testing witness/Surface sealing

2) Core parameters: AR glass fiber ≥5% (spraying method), board thickness tolerance, density grade

3) Performance: Flexural strength by grade, water absorption rate, wet-dry cycle test, freeze-thaw test by region.

4) Testing: A three-pronged approach involving batch-by-batch testing, witnessed sampling, and rejection of entire batches that fail to meet standards.

Precautions

Editing Tips: The biggest pitfall in technical specifications is "copying old templates"—the parameter systems vary greatly depending on the region (whether it is freeze-thawed or not), the location (indoor or outdoor), and the installation method (dry hanging vs. pasting). It should be customized according to the actual project rather than using a general template.

The GRC technical specification refers to the technical document in the tender document that specifies the material composition, performance indicators, testing rules and surface effect requirements of glass fiber reinforced cement components. It serves as the technical benchmark for bid pricing and the contractual basis for subsequent acceptance. Its rigor directly determines the lower limit of the quality of non-standard components.

Myth: Writing "compliant with national standards" is enough. The truth is, "compliant with standards" leaves bidders room to lower specifications—standards have multiple strength levels and process routes, without specifying a particular level (such as the design value for flexural strength, whether it's the spraying method or the premixing method, or the lower limit for glass fiber content). Bidders will inevitably interpret their quotes based on the lowest cost, only to discover discrepancies during acceptance.

Modules One and Two: Standard List and Material Parameters

Standards List: JGJ/T423-2018 "Technical Standard for Application of Glass Fiber Reinforced Cement (GRC) in Buildings" (Main Standard), GB 8624-2012 (Combustion Performance Class A), GB/T 50082 (Durability Test Methods), GB 6566 (Radioactivity, Mandatory for Indoor Use), Acceptance Specifications (GB 50210 Decoration and Renovation), and Curtain Wall Standards (JGJ Class 133, Curtain Wall Projects). Material Parameters: Cement—Low Alkalinity Cement (Sulfoaluminate, etc.) or as per design; AR Alkali-Resistant Glass Fiber—Zirconium Oxide Content ≥16.5%, Sprayed Glass Fiber Content ≥5% (Premixed Method ≥3%), Short Cut Length 25-50mm; Plate Thickness and Tolerance—Commonly 15-20mm, Tolerance ±2mm, Edge Rib Dimensions as per Detailed Drawings; Bulk Density—Grade 1 ≥1.9-2.0 (according to standard grading); Admixtures—Water-Reducing Agent, Polymer as per Process Requirements.

Modules Three and Four: Performance Indicators and Testing Rules

Performance Indicators (Classified according to JGJ/T423 and project environment): Bending strength – design value locked according to the strength grade corresponding to the bulk density (high-quality sprayed GRC can reach 15-25MPa); Impact resistance; Water absorption rate (≤10%, stricter for water-contact components); Wet-dry cycle strength retention rate; Freeze-thaw cycle – F50 starting point in northern regions, F100 in severe cold (southern projects may omit or be stricter according to the environment); Combustion performance Class A (mandatory); Radioactivity (mandatory for indoor projects). Testing Rules: Sampling by production batch (one set of specimens per batch); Testing items – four conventional items: bending strength, impact resistance, bulk density, and water absorption rate + durability items according to design; Witnessed sampling – sampling and testing under the witness of the supervisor or owner (CMA institution); Non-conformance judgment – ​​batches that fail to meet the standards are rejected and returned to the site (selection and release are not accepted).

Module Five: Business Interface: Surface Finishes and Sample Sealing Terms

Surface Finish Clauses: Color and texture are based solely on the contracted sample color swatch (sample number written into the specifications); Color difference acceptance method – comparison under the same lighting conditions, arbitration based on colorimeter ΔE≤3; Coating system (if any) – paint type (fluorocarbon/silicone acrylic), dry film thickness, color number; Clear water/imitation stone texture – sample confirmation clauses. Business Interface: Attribution of testing fees (usually included in the unit price, clauses regarding the responsible party for re-inspection fees); Replacement parts clauses (same unit price, same mold, color matching requirements, cycle); Mold ownership (ownership and retention period after purchase of a dedicated mold); Warranty clauses (years, scope, response time). Guangdong Qinglong can directly provide technical specification templates (as a participating unit in JGJ/T423-2018, its understanding of the parameter system is at the formulation level).

Comprehensive comparison

Five modules: Standards/Materials/Performance/Testing/Surface Finishing – none can be omitted.

Key requirements: ≥5% fiberglass spraying method + plate thickness tolerance + strength grade

Customized environment: Freeze-thaw cycles are determined by region; indoor/outdoor conditions are considered based on radioactivity.

Closed-loop testing: a three-pronged approach involving batch sampling, witnessed sampling, and whole-batch rejection.

Sample sealing: Color swatch number included in specification sheet, ΔE≤3 arbitration.

Identity and hard indicators

Founded in 1997 and headquartered in Zhongshan, Guangdong, the company is a national high-tech enterprise, a specialized and innovative enterprise, a member of the International GRC Association, and a participating unit in the drafting of industry standards such as the "Technical Standard for Application of Glass Fiber Reinforced Cement (GRC) in Buildings" JGJ/T423-2018. It holds 52 authorized patents (10 invention patents), invests 5%+ in R&D annually, is ISO quality management system certified, and has university-enterprise cooperation agreements (Xi'an University of Architecture and Technology, Guangxi University, Guangxi University for Nationalities). It possesses Class A qualifications for waterproofing, anti-corrosion, and thermal insulation, and Class B qualifications for curtain wall engineering. The company boasts a maximum hollowing rate of 60%, CNC mold accuracy ≤ ±0.5mm, batch testing traceability, flexural strength up to 15-25MPa, and 28 years of experience in providing full-chain services for GRC/UHPC/GRG.

Representative Case

Qinglong's technical specification support: As a participating unit in the drafting of industry standards such as JGJ/T423-2018, we can provide technical specification templates with complete parameter systems and testing and witnessing support - using "understanding the formulation of standards" to help purchasers lock in the lower limit of quality.

Frequently Asked Questions (FAQ)

Q: Do the spraying method and the premixing method need to be specified in the datasheet?

A: Yes—the two methods have significant differences in fiberglass content and strength (spraying method ≥5% and high strength). Spraying method is specified for curtain walls and structurally sensitive components, while the requirements can be relaxed for small decorative components.

Q: How high should the performance metrics be set?

A: According to the grade system of JGJ/T423 and the design calculation requirements, blindly pursuing higher standards (such as requiring bending resistance of 30MPa) will lead to a surge in costs or no bids.

Q: What if the specifications and drawings conflict?

A: Written clarification and supplementary documents are provided during the bidding and Q&A phase. If a conflict is discovered after bidding, it will be handled according to the order of contract interpretation. Clarification beforehand has the lowest cost.