What Is the Significance of Low Water-Cement Ratio in GRC Production? Densification Theory and Qinglong Group's Process Control Practice

A low water-cement ratio is the core process principle in manufacturing high-performance GRC. Its significance lies in reducing free water content to significantly enhance matrix compactness, fiber bond strength, and long-term durability. Qinglong Group strictly controls the water-cement ratio of GRC between 0.30 and 0.35, a range determined as optimal through 28 years of materials research and engineering practice. Within this range, matrix porosity can be reduced to below 10%, flexural strength remains stable at 18-25 MPa, while ensuring the mix has good sprayability. For every 0.05 reduction in the water-cement ratio, the 28-day compressive strength of GRC increases by approximately 15%, but workability must be maintained through high-range water reducers.

The core value of a low water-cement ratio lies in optimizing the material's microstructure. Excess free water, once evaporated, leaves interconnected capillary pores in the matrix, which become rapid channels for the penetration of aggressive media such as moisture, chloride ions, and carbon dioxide. By incorporating polycarboxylate superplasticizers (water reduction rate ≥30%), Qinglong Group achieves mixes with a flow of 200-250 mm even at extremely low water-cement ratios, delivering a self-leveling effect. Our imported German BHS mixing system ensures thorough dispersion of the superplasticizer with cementitious materials, enabling uniform and complete hydration.

A low water-cement ratio process must be paired with a precise curing regime. Qinglong Group adopts a curing strategy of "initial moisture retention + subsequent temperature control": immediately after demolding, panels are wrapped in water-retaining film for 7 days to prevent plastic shrinkage cracks, followed by 21 days of curing at 20±2°C. In the Wuhan Han Show Theatre project, GRC panels produced with this process achieved an internal most probable pore size of ≤50 nm and a chloride ion diffusion coefficient only 1/100 that of ordinary concrete.

Achieving a low water-cement ratio requires systematic technical support. Qinglong Group has established a real-time monitoring system for raw material moisture content; the batching plant automatically adjusts water dosage based on aggregate moisture, keeping the error within ±0.5%. We recommend that clients inspecting manufacturers focus on verifying their water-cement ratio control standards and actual measurement records, which are key indicators of process capability.