The contractor's personal preference also matters when choosing wet or dry shotcrete for a project. Contractors who have more experience with one method than the other tend to prefer this method. Wet and dry shotcrete require completely different equipment to be installed, so the type of equipment a contractor has also plays an important role in the decision-making process.
Temperature will affect the curing time of the material, making it another factor in deciding which shotcrete process is right for the job. Shotcrete also doesn't hang in cold weather, especially in overhead applications, and there's an increase in material that springs back or doesn't stick to the substrate it's being propelled into. In warm weather, the material may require more extensive curing to prevent cracking.
Certain types of overhead locations at specific depths may be suitable for one process or another. The location of certain areas can prevent proper nozzle posture and distance. Sometimes in mining applications, harsh conditions require nozzles to be fired from their knees, stomachs and backs from farther or closer than standard. All of these unique circumstances play a role in the selection process.
There is an old saying that "shotcrete is not a product, but a craft". It is important to keep this in mind when specifying shotcrete jobs. Usually try to keep projects open to both processes when bidding. In an open competitive bidding situation, a good way to apply will result in a winning bid.
Additionally, this allows contractors to use methods they are familiar with and ensures that owners and architects have a good chance of a successful project. Some jobs are clearly suitable for wet processes, while others are more suitable for dry processes. Many jobs are not suitable for either approach. In other cases, wet shotcrete and dry shotcrete are used in one project at the same time, or in different phases of the same project.
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Executive Editor:Zhang Wen