Here are some strategies to address this issue:
1. Material Preparation
Use Chilled Water: Replace normal water with chilled water during mixing to reduce the initial temperature of the shotcrete mix.
Use Ice as Part of the Water Content: If possible, add crushed ice to the mix. Ensure the ice is fully melted before pumping.
Store Materials in a Cool Place: Keep aggregates and cement in a shaded or cooled area to prevent them from absorbing excessive heat.
Use Set Retarders: Add chemical admixtures to slow down the hydration process, increasing the working time in high temperatures.
2. Machine Operations
Monitor Equipment Temperature: High ambient temperatures can overheat pumps and other mechanical components. Regularly check and maintain cooling systems.
Use Proper Lubrication: Ensure all moving parts are well-lubricated with high-temperature-rated grease or oil to prevent wear and tear.
Schedule Work During Cooler Hours: Operate during early mornings or late evenings to avoid peak heat.
3. Application Techniques
Pre-wet the Surface: Spray water on the receiving surface to reduce its temperature and prevent rapid water absorption from the shotcrete.
Shorten Conveying Distances: Minimize the distance between the machine and application area to reduce exposure to high temperatures during transport.
4. Worker Safety
Provide Shade or Cooling Systems: Install tents or fans near the work area to protect workers from heat stress.
Enforce Hydration Breaks: Ensure workers take frequent breaks and drink plenty of water.
Use Heat-resistant Gear: Equip operators with protective clothing designed for high-temperature environments.
5. Quality Control
Monitor Concrete Temperature: Use a thermometer to ensure the temperature of the shotcrete mix stays within acceptable limits (usually below 30°C or 86°F).
Adjust Mix Design: Work with a concrete technologist to modify the mix for high-temperature conditions.
By integrating these practices, you can maintain the performance of the wet shotcrete machine and ensure the quality of the application even under high-temperature conditions.
