How to Avoid Rapid Moisture Evaporation from GRC Exterior Walls in High-Temperature Regions? Moisture Evaporation Control Solutions and Practical Strategies

During the construction and use of GRC exterior walls in high-temperature regions, excessively rapid moisture evaporation can easily lead to problems such as surface cracking, insufficient strength development, and bonding failure. Material optimization, construction control, and protective measures are required to effectively slow moisture evaporation and ensure component quality and durability. Drawing on project experience in high-temperature regions such as Hainan and Guangxi, Qinglong analyzes the core control solutions.

I. Material Formulation Optimization and Pretreatment Measures

Start from the material source to improve water retention capacity. Adding high-efficiency water-retaining agents to the GRC mix, such as hydroxypropyl methylcellulose (HPMC) at a dosage of 0.1%-0.3%, can significantly reduce the rate of moisture evaporation; in high-temperature projects, Qinglong reduced moisture evaporation by 30% with this formulation. Select low-hydration-heat cement, such as slag Portland cement, to slow the heat release from hydration and prevent accelerated evaporation caused by excessively high surface temperatures. Pretreat aggregates by pre-wetting quartz sand and other aggregates in advance, controlling moisture content at 5%-8% to reduce internal water consumption of the mix. Add retarders to extend the initial setting time, allowing sufficient time for full hydration and preventing early water loss.

II. Moisture Evaporation Control During Construction

Standardize construction procedures and avoid working during high-temperature periods. Arrange construction times reasonably, avoiding the hot period from 10 a.m. to 4 p.m. and choosing early morning or evening to reduce the impact of ambient temperature on evaporation. Erect temporary shading facilities, covering the work area with shade nets or colored steel sheets to reduce direct sunlight and lower the surface temperature by 5-8°C. Adopt mist-spraying moisturizing measures, installing spray devices around the work area to raise ambient humidity above 60% and slow surface moisture evaporation. Control the area worked per pass, constructing in sections and curing promptly to avoid rapid moisture loss from large exposed areas; Qinglong applied this method in the Sanya Festival Plaza project, effectively controlling moisture evaporation during the construction stage.

III. Moisture Protection Plan During the Curing Stage

Curing is a critical step in moisture control in high-temperature regions and requires enhanced moisturizing. Use the covering curing method: immediately after components are formed, cover them with geotextile or plastic film; the plastic film must be tightly sealed to prevent moisture penetration and evaporation, with a curing period of no less than 7 days. Use the mist-spray curing method: spray mist 3-4 times a day to keep the covering moist, avoiding high-pressure water spraying directly onto the GRC surface to prevent surface sanding. Use the steam curing method: when conditions permit, apply low-temperature steam curing with the temperature controlled at 40-50°C and humidity ≥95%, which accelerates strength development while preventing excessively rapid moisture evaporation; in the Guangxi New Media Center project, Qinglong used steam curing to ensure component strength met standards in the high-temperature environment.

IV. Moisture Retention and Protection During Long-Term Use

Long-term protection can reduce moisture loss and improve component durability. Apply penetrating sealers to the surface to form a breathable waterproof film that prevents excessively rapid moisture evaporation while allowing internal water vapor to escape, avoiding blistering. Clean and moisturize regularly: clean surface dust quarterly, and before each summer's high temperatures arrive, apply a dedicated moisturizing protective agent to replenish surface moisture. Optimize component styling design to reduce large flat exposed areas, adding lines and undulating forms to lower surface wind speed and slow the rate of moisture evaporation. Through whole-process moisture control, Qinglong has achieved a pass rate of over 99% for GRC projects in high-temperature regions, effectively avoiding quality problems such as cracking.