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What are the types of concrete spraying? The four main methods of concrete spraying

2025-03-25 Visits:

   What are the types of concrete spraying?  Concrete spraying techniques can be categorized based on material mixing methods, equipment types, and construction characteristics. The four main types are as follows:

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   1. Dry Spray Method

   Characteristics:

   Material Mixing: Cement, aggregate, and accelerator are dry-mixed in proportion and transported to the nozzle via compressed air, where water is added.

   Advantages: Simple equipment (such as a dry sprayer), long transport distance (up to 150–200 meters), suitable for lightweight porous aggregates.

   Disadvantages: High dust concentration at the nozzle, high rebound rate (approximately 40–50%), and difficult water-cement ratio control.

   2. Damp Spray Method

   Characteristics:

   Material Mixing: Aggregate is pre-wetted (with 5–8% moisture content) before mixing with cement and then sprayed.

   Advantages: Reduces dust compared to dry spraying (about 60 mg/m³), and equipment is similar to dry sprayers (dual-use dry/damp sprayers).

   Disadvantages: Still has a certain rebound rate (around 15–25%) and challenges in water-cement ratio control.

   3. Wet Spray Method

   Characteristics:

   Material Mixing: Cement, aggregate, and water are fully mixed into a wet mixture before being transported through a wet sprayer, with an accelerator added at the nozzle.

   Advantages: Low dust, low rebound rate (below 15%), and stable concrete quality with controlled water-cement ratio.

   Disadvantages: Complex equipment (requires power-driven transport), prone to pipeline blockage, and higher cost.

   4. Hybrid Spray Method (SEC Method)

   Characteristics:

   Material Mixing: Materials are added in stages, first mixing cement-coated sand mortar, then combining it with aggregate before spraying, integrating both dry and wet spraying techniques.

   Advantages: Further reduces dust and rebound rate while improving concrete homogeneity.

   Disadvantages: Complex equipment (requires a mortar pump and sprayer), more intricate operation, and mainly used for large-section projects.

   Additional Notes

   Mainstream Application: The wet spray method has become the dominant choice due to its environmental benefits and stable quality (e.g., tunnel support and slope reinforcement).

   Equipment Classification: Sprayers can be categorized into piston-type, screw-type, and rotor-type based on structure, with rotor-type wet sprayers being the most widely used.

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