What is the difference between wet shotcrete and dry shotcrete? Wet shotcrete and dry shotcrete are two different shotcrete processes, which differ significantly in material mixing methods, construction processes, performance, etc. The following are the core differences between the two:

   1. Process flow and material mixing method

   Wet shotcrete: Cement, aggregates, water and admixtures are mixed in proportion to form commercial concrete in advance, transported to the nozzle through a pumping system, and sprayed to the sprayed surface after mixing with liquid accelerator. Water and materials have been fully integrated during the mixing stage, and the mixing uniformity is better.

   Dry shotcrete: After dry mixing cement, aggregates and powdered accelerator, they are transported to the nozzle through compressed air and then mixed with high-pressure water for spraying. The mixing of water and materials occurs at the end, which is prone to uneven mixing.

   2. Dust and construction environment impact

   Wet shotcrete: Low dust concentration (dust near the machine is about 60 mg/m³), reducing the risk of silicosis among workers, and better environmental protection.

   Dry spraying concrete: water is added to the mixture at the nozzle, resulting in high dust concentration and poor construction environment.

  3. Rebound rate and construction efficiency

   Wet spraying concrete: low rebound rate (about 15%), less material waste, and a thicker concrete layer can be sprayed at one time, with high construction efficiency.

   Dry spraying concrete: The rebound rate is as high as 40%-50%, the material loss is large, and multiple spraying is required to reach the designed thickness.

  4. Concrete strength and quality

   Wet spraying concrete: The water-cement ratio is precisely controllable, the concrete density is high, the compressive strength is stable (can reach C30 or above), and the support quality is better.

   Dry spraying concrete: The water-cement ratio is greatly affected by manual operation, and it is easy to have problems such as uneven strength and surface cracking.

   5. Equipment structure and applicable scenarios

   Wet spraying machine: It needs to be equipped with mixing equipment and liquid accelerator pump. The structure is complex, but it can form a mechanized operation line, which is suitable for large tunnels, underground projects, etc.

   Dry spraying machine: The equipment is simple and light, suitable for small-volume projects or temporary support, but the maintenance cost is high (the bonding plate wears quickly).