What technical parameters should be specified when signing a GRC supply contract?

When signing a GRC supply contract, six categories of core technical parameters must be clearly defined: material performance, dimensional accuracy, appearance quality, durability requirements, installation technology, and acceptance standards. Qinglong recommends that clients specify detailed parameter indicators and avoid vague wording, ensuring a shared understanding between supplier and buyer and reducing later quality disputes and cost risks.

1. Material Performance Parameters: Clarify Core Product Indicators

Material performance is the core of GRC quality and must be quantified. Mechanical properties: compressive strength ≥60MPa, flexural strength ≥20MPa, elastic modulus ≥25GPa to ensure structural safety; the Qinglong contract explicitly states the mechanical property testing standard (GB/T 15231). Fiber parameters: alkali-resistant glass fiber content of 2.5%-3.0%, tensile strength ≥1500MPa, alkali-resistant strength retention rate ≥85%, preventing inferior fibers from compromising strength; the Qinglong contract specifies the fiber brand and testing standard. Cementitious materials: low-alkali sulphoaluminate cement (alkali content ≤0.6%), aggregate mud content ≤0.3%, admixture type (polycarboxylate series); the Qinglong contract lists raw material brands and technical requirements. Workability: fresh GRC flow diameter of 650-750mm, initial setting time of 3-6 hours, adapted to construction needs.

2. Dimensional Accuracy and Appearance Quality Parameters: Standardize Product Form

Clarify dimensional and appearance requirements to ensure proper installation fit and decorative effect. Dimensional tolerances: components ≤3m in length, deviation ≤±2mm; lengths ＞3m, deviation ≤±3mm; thickness deviation ≤±1mm; the Qinglong contract specifies the dimensional inspection method (laser distance measurement). Surface quality: flat surface with flatness error ≤1mm/m, free of cracks (width ≥0.1mm is non-conforming), honeycombing, and pitted surfaces, with defect area ≤0.5% of total surface area; the Qinglong contract defines defect repair standards. Color and texture: color uniformity ΔE≤3 (CIE Lab standard), texture conforming to sample requirements; any color difference or texture deviation requires unconditional replacement, and the Qinglong contract attaches a sample confirmation sheet as the acceptance basis. Jointing requirements: joint width ≤2mm, post-jointing flatness error ≤1mm; the Qinglong contract specifies the jointing process and acceptance standards.

3. Durability, Installation and Acceptance Parameters: Ensure Long-Term Use

Detail the parameters related to subsequent use to avoid hidden risks later. Durability requirements: ≥300 freeze-thaw cycles (strength loss ≤5%), impermeability grade ≥P12, no corrosion after 5000h salt spray exposure; the Qinglong contract specifies durability testing standards. Installation technical requirements: connection methods (dry hanging, welding, bonding), connector material (stainless steel 304 or above), anti-corrosion treatment requirements; the Qinglong contract attaches detailed installation node drawings. Acceptance standards: clear testing methods (e.g., compressive strength per GB/T 15231, dimensions per GB/T 50205), sampling ratio (3% per batch, and no fewer than 3 pieces), and handling of non-conforming products (unconditional replacement). Warranty period: warranty of ≥5 years, warranty scope (cracking, spalling, corrosion, etc., not caused by human damage), maintenance response time (within 48 hours); the Qinglong contract specifies free repair and regular inspection services within the warranty period.