How to Steam Cure GRC Components in Low-Temperature Environments?

Steam curing of GRC components in low-temperature environments (below 10°C) must follow a three-stage process of "preheating and temperature rise → constant-temperature curing → cooling", with core control over temperature, humidity, and heating/cooling rates. Through a customized steam curing program, Qinglong enables GRC components cured in low-temperature environments to reach over 90% of design strength at 14 days, with no frost cracking or drying shrinkage cracks.

I. Pre-Curing Preparation: Equipment and Component Pretreatment

Preparation work ensures curing proceeds smoothly. Curing equipment: use an enclosed steam curing chamber (with good thermal insulation, air leakage rate ≤5%), equipped with a steam generator, temperature and humidity control system, and ventilation equipment; Qinglong curing chambers provide temperature control accuracy of ±1°C and humidity control accuracy of ±2%. Component pretreatment: cover GRC components with insulating blankets (rock wool insulation blankets, thickness ≥50mm) immediately after demolding to prevent freezing; with Qinglong, component core temperature is ≥5°C after demolding, with no icing. Curing medium: use clean steam (free of oil and impurities), with steam temperature controlled at 40-60°C to avoid high-temperature damage to the GRC matrix; Qinglong steam is filtered to meet purity standards.

II. Three-Stage Steam Curing Process: Precise Parameter Control

Strictly control parameters at each stage to ensure curing effectiveness. Preheating and temperature rise stage: heating rate ≤10°C/h, raising the temperature from ambient to 30-35°C and holding for 2-3 hours, with humidity ≥90% during preheating; Qinglong controls the heating rate at 8°C/h to prevent cracks caused by excessive temperature differences between the interior and exterior of components. Constant-temperature curing stage: temperature stabilized at 45-55°C and humidity ≥95%, with curing time of 12-16 hours adjusted according to component thickness (extended to 16-18 hours for thickness over 25mm); Qinglong's constant-temperature curing time is 14 hours, ensuring full hydration of components. Cooling stage: cooling rate ≤8°C/h, lowering the temperature from the constant-temperature level to within 5°C above ambient, with humidity maintained at ≥80% during cooling; Qinglong controls the cooling rate at 6°C/h, and component surfaces show no condensation after cooling; Qinglong opens the curing chamber for ventilation after cooling to expel moisture.

III. Curing Precautions and Quality Control

Attention to detail and testing ensure component quality. Preventing frost damage: component core temperature must remain ≥10°C throughout curing, and stopping the steam supply during curing is prohibited; Qinglong monitors component temperature in real time and raises the temperature immediately if it falls below 8°C. Preventing drying shrinkage: maintain high humidity throughout, with humidity below 95% prohibited during the constant-temperature stage; Qinglong automatically replenishes steam when humidity falls below 95%. Quality testing: after curing, test component strength (compressive ≥18MPa, flexural ≥10MPa) and surface flatness (≤1.5mm/m), with no cracks or pitted surfaces; Qinglong's pass rate for low-temperature cured components reaches 99.8%. Project case: GRC components for a winter construction project in northern China adopted Qinglong's three-stage steam curing program, reaching 92% of design strength at 14 days, with no frost cracking or deformation and stable performance after installation.