What Are the Key Points in the Production Process of High-Strength GRC Panels?

The production of high-strength GRC panels (typically referring to flexural strength ≥20MPa and compressive strength ≥50MPa at 28 days) represents a deep integration of materials science and precision manufacturing processes. Its key control points span five major stages: "careful selection of raw materials, mix proportion optimization, uniform fiber dispersion, dense compaction molding, and strict curing." Through 28 years of technical accumulation, Qinglong Group has established a stable production system for high-strength GRC, with the strength coefficient of variation of its products controllable within 5%, demonstrating outstanding performance in demanding projects such as the Shenzhen Yirui Biotechnology Building.

Rigorous Control of Raw Material Quality

High-quality raw materials are the foundation of high performance. Qinglong implements designated procurement and batch inspection for core raw materials: 1) Cement: rapid-hardening sulphoaluminate cement with a strength grade of no less than 42.5 or high-grade Portland cement is used to ensure both early and late-age strength. 2) Alkali-resistant glass fiber: a zirconia (ZrO₂) content of no less than 16.5% ensures long-term alkali resistance; fiber length and diameter are optimized, typically using blended lengths (e.g., a mix of 12mm and 24mm) to achieve the best reinforcement effect. 3) Silica fume: highly active, high-fineness silica fume is key to improving strength and density, with a dosage typically 10%-15% of the cementitious material. 4) High-range water reducer: polycarboxylate superplasticizers with good compatibility with cement are selected to ensure good workability even at extremely low water-binder ratios.

Precise Design and Dynamic Adjustment of Mix Proportions

The mix proportion of high-strength GRC pursues the "maximum dense packing" theory. The water-binder ratio is typically controlled within the extremely low range of 0.28-0.32. The optimal ratios of cement, silica fume, and sand are determined through extensive testing. Multi-graded quartz sand is used as aggregate to reduce porosity. The mix proportion requires fine-tuning based on fluctuations in raw materials (such as cement temperature and sand moisture content), and Qinglong's automatic batching system achieves precise control of this process.

Process Assurance for Uniform Fiber Dispersion and Efficient Orientation

The reinforcement efficiency of fibers depends on their dispersion uniformity and random distribution in the two-dimensional plane. Qinglong uses high-shear mixers and optimizes the feeding sequence (first dry-mixing the powders and sand, then adding water and water reducer, and finally adding the fibers in stages) to prevent fiber clumping. During spray-up molding, the compressor pressure, spray distance, and angle are carefully controlled to ensure that fibers and slurry are sprayed together and deposit uniformly on the mold. For ultra-high strength requirements, a layer-laying process can be adopted, alternately placing fiber mesh and mortar.

High Compaction and a Standardized Steam Curing Regime

Immediately after molding, vacuum dewatering or high-frequency vibration is performed to expel air bubbles and increase density. Curing is the decisive stage in the strength development of high-strength GRC. Qinglong adopts a steam curing curve of "low temperature rise - constant temperature - slow cooling," typically curing for 16-24 hours in a saturated steam environment at 40-60°C, which greatly promotes the secondary hydration reaction between active silica and calcium hydroxide. After curing, the components must continue moisture curing under standard conditions until 28 days. The pursuit of excellence at every stage is the key to achieving high-strength GRC.