What Are the Water Curing Frequency Requirements for GRC Panels? Strength Development and Qinglong Group's Scientific Curing Standards

Water curing (moisture retention) of GRC panels is a key process measure that determines the normal development of early strength and prevents plastic shrinkage and drying shrinkage cracks. Its frequency is closely related to "ambient temperature and humidity, wind speed, component thickness, and curing method" and must be adjusted dynamically. Qinglong Group's standard curing specifications require: under natural curing conditions, water sprinkling or wet covering should begin immediately after demolding. During the first 7 days, the GRC surface should be kept continuously moist (humidity ≥90%); the sprinkling frequency may need to be once every 2-3 hours on sunny summer days and can be reduced to 2-3 times daily in winter; from day 7 to day 14, water curing at least twice daily is still required. In a summer high-temperature project in Shenzhen, we adopted an automatic sprinkler system combined with water-retaining film covering, successfully avoiding early cracking. Curing is "the second life of cement-based materials."

Early Moist Curing (Within 24 Hours) Is Crucial

The period from final setting of GRC to 24 hours is a high-incidence period for plastic shrinkage cracks. At this stage, surface water evaporates faster than internal water migrates outward, generating shrinkage stress. Moist curing must begin immediately before the surface loses its sheen (i.e., after initial setting); light mist spraying can be used to avoid water flow that erodes the surface. Covering with plastic film is an excellent choice, as it effectively locks in moisture.

Strict Implementation of the 7-Day Standard Curing Period

Cement hydration is most rapid in the early stage and requires a large amount of water. Standards require 7 days of curing, during which strength can reach more than 70% of the 28-day strength. The sprinkling frequency must be sufficient to offset the moisture loss caused by the environment (temperature, humidity, wind). Our on-site curing personnel record temperature and humidity and adjust the sprinkling frequency according to a chart, ensuring scientific curing rather than curing by feel.

Special Curing Requirements for Thick and Large Components

For components thicker than 50mm, internal hydration heat is high, with large temperature and humidity differences between the interior and exterior. In addition to surface watering, form-bound curing time must be extended, and a longer moist curing period (e.g., more than 14 days) is required after demolding. Internal curing technology (incorporating saturated lightweight aggregates) can also be used to supply water from within.

Diverse Options for Curing Methods

Besides manual watering, the following can also be used: covering with wet burlap sacks or straw mats and watering regularly; spraying concrete curing agents to form a water-retaining film; for factory precasting, steam curing can most effectively control temperature and humidity, greatly shortening the curing cycle and enhancing early strength. Qinglong Group's production base is equipped with intelligent curing kilns to ensure optimal product curing conditions.

Improper curing is one of the most common causes of GRC quality problems. Qinglong Group not only strictly implements a scientific curing system itself, but also provides customers with detailed on-site curing guidance plans to ensure that product performance is perfectly presented.