Does rain affect shotcrete? Yes, rain can significantly affect shotcrete application and performance. Here's how:

   1. During Application:

   ① Rainwater dilutes the shotcrete mix, reducing its strength and adhesion to surfaces.

   ② Excessive moisture causes aggregates to separate from the cement matrix, leading to poor bonding and durability.

   ③ Heavy rain may wash away fresh shotcrete before it sets, requiring costly reapplication.

   2. During Curing:

   ① While shotcrete requires some moisture to cure properly, prolonged rain can leach out cementitious materials, weakening the final product.

   ② Waterlogged conditions slow down the hydration process, delaying strength development.

   How to Mitigate Rain Effects?

   ① Avoid spraying shotcrete in rainy or high-humidity conditions.

   ② Use temporary shelters or tarpaulins to protect the work area.

   ③ Add accelerators to the mix to speed up setting if light rain is unavoidable.

   ④ Ensure proper drainage to prevent water pooling on cured surfaces.

   Post-application rain (after 72 hours) generally becomes less detrimental as the material gains strength, though prolonged exposure should still be avoided. Proper curing compounds or membranes are essential in rainy environments.