What Are the Material Mix Ratio Characteristics of Lightweight GRC Shapes? Mix Ratio Analysis and Performance Assurance

Lightweight GRC shapes take light weight and high strength as their core advantages, making them suitable for weight-sensitive applications such as large spans and suspended installations. Their material mix must reduce self-weight while ensuring core properties such as strength and durability. Drawing on years of R&D and production experience with lightweight GRC, Qinglong analyzes the core features of material mix design and performance optimization solutions.

1. Cementitious Material Optimization: Balancing Low Density and High Strength

The selection and proportioning of cementitious materials is the foundation for achieving lightweight construction. Cement selection: low-alkali sulfoaluminate cement with low density and high strength is preferred, replacing traditional ordinary Portland cement, reducing density by 10%-15% while ensuring compressive strength ≥40MPa. Active admixture addition: active admixtures such as silica fume and fly ash are added at a dosage of 15%-20% to replace part of the cement, reducing material density while improving interfacial bond strength and compactness. Through admixture optimization, Qinglong lightweight GRC maintains a density of 1600-1800kg/m³, more than 10% lower than conventional GRC. Cementitious material dosage control: while meeting strength requirements, the amount of cementitious material is reduced; through mix ratio optimization, cementitious material usage is reduced by 5%-8%, further lowering self-weight.

2. Aggregate Gradation Adjustment: Balancing Light Weight and Workability

Aggregate gradation directly affects material density and forming performance. Lightweight aggregate selection: quartz sand is partially replaced with lightweight aggregates such as ceramsite and perlite at a dosage ≤30%, reducing overall density while ensuring good bonding between aggregates and the cement matrix to avoid strength loss. Fine aggregate dominance: fine quartz sand (particle size 0.1-1.2mm) is used as the main aggregate, reducing coarse aggregate usage and improving slurry flowability to facilitate the forming of complex lightweight shapes, with fine aggregates accounting for ≥80%. Aggregate bulk density optimization: through particle gradation tests, the optimal aggregate gradation is determined to minimize aggregate bulk density and porosity, reducing cementitious material usage; the aggregate bulk density of Qinglong lightweight GRC is 12% lower than conventional mixes.

3. Fiber Dosage and Type Optimization: Improving Reinforcement Efficiency

Fibers are the core of strength assurance in lightweight GRC, and reinforcement efficiency must be improved. Fiber type selection: alkali-resistant glass fibers with high elastic modulus are selected, with continuous fibers preferred; reinforcement efficiency is 30% higher than that of chopped fibers, reducing fiber usage while ensuring strength. Fiber dosage control: chopped fiber dosage is controlled at 2%-3%, and continuous fiber dosage ≤1.5%; uniform dispersion technology ensures fibers are evenly distributed in the slurry, avoiding localized agglomeration—Qinglong uses a high-pressure spray forming process to achieve uniform fiber distribution. Fiber surface treatment: fibers surface-treated with silane coupling agents are selected to improve bond strength with the cement matrix, further enhancing reinforcement effects and reducing fiber usage.

4. Precise Admixture Proportioning: Synergizing Performance Optimization and Light Weight

Through precise proportioning, admixtures achieve multiple performance optimizations. Water reducer addition: high-efficiency polycarboxylate water reducers are selected at a dosage of 0.8%-1.2%, lowering the water-binder ratio to 0.35-0.4; while ensuring slurry flowability, water usage is reduced, improving material compactness and strength and indirectly achieving light weight. Air-entraining agent addition: an appropriate amount of air-entraining agent (dosage 0.05%-0.1%) is added to introduce tiny bubbles, reducing density while improving frost resistance and crack resistance, with bubble diameter controlled at 0.1-0.5mm. Retarder adjustment: retarders are added according to construction environment temperature to adjust setting time, preventing forming defects caused by excessively rapid slurry setting and ensuring smooth forming of lightweight complex shapes. Through admixture optimization, Qinglong lightweight GRC meets industry standards for overall performance while reducing self-weight by 10%-15%.