When Is the Best Time to Demold GRC Components? Demolding Process and Qinglong Group's Timing Control Standards

Determining the demolding timing of GRC components requires comprehensive consideration of four factors: "strength development, temperature conditions, component shape, and production efficiency." The core control indicator is compressive strength reaching 5-8MPa (or flexural strength reaching 2-3MPa). Based on 28 years of production data, Qinglong Group has summarized a scientific demolding window: under standard curing conditions (20°C, RH≥95%), conventional components (thickness 20-30mm) can be demolded in 16-24 hours; steam curing (80°C) can shorten this to 4-6 hours; winter low temperatures (5°C) require extending the time to 36-48 hours. In the production of red double-curved panels for the Wuhan Hanxiu Theater, through measured strength (dual verification with rebound hammer + test cubes), we precisely controlled the demolding strength at 6±0.5MPa, achieving a demolding yield rate of 99.9% for the 9,000 special-shaped panels. Demolding is a balancing art of precision and efficiency.

Strength Control Is the Core Basis for Demolding Decisions

Compressive strength tests are conducted on test cubes cured under identical conditions; when the strength reaches 5MPa, side forms can be removed, and at 8MPa, components can be lifted and moved. The Qinglong Group laboratory tests one set of cubes every 4 hours and, combined with on-site rebound hammer data, determines the demolding timing through dual control. For critical components, non-destructive testing instruments are used to monitor internal strength development.

Ambient Temperature Is the Key Factor in Time Variation

A temperature-strength development curve has been established: at 20°C, 24-hour strength can reach 8MPa; at 10°C, 48 hours are required; at 30°C, only 12 hours are needed. Through the temperature control system of our curing chambers (precision ±2°C), we stabilize the rhythm of strength development to ensure consistent demolding strength across different seasons.

Component Characteristics Determine Differences in Demolding Strategies

Flat panel components can be demolded early (strength 5MPa); ribbed panels must wait until rib strength is fully developed; special-shaped panels require evaluation of demolding stresses, with step-by-step demolding adopted when necessary. In the demolding of wave panels for the Hainan Convention and Exhibition Center, we developed the patented "airbag-assisted demolding" technique to avoid damaging the complex shapes.

Mold Turnover and Quality Assurance Require Coordinated Consideration

Demolding too early (strength below 4MPa) easily causes chipped edges and corners, while demolding too late (strength above 10MPa) affects mold turnover. By optimizing the mix proportion (adding early-strength admixtures) and the curing regime, we keep the mold turnover cycle for standard panels within 24 hours while ensuring demolding quality.

Demolding timing is a critical decision point in GRC production. Through scientific testing and refined management, Qinglong Group achieves the optimal balance between quality and efficiency.