What is the difference between concrete and shotcrete? The main difference between "concrete" and "shotcrete" lies in their application method:

   1. Definition & Composition

   ① Concrete: A mixture of water, aggregates (sand, gravel), and cement, poured into molds to harden into structural elements. It relies on formwork for shaping.

   ② Shotcrete: Concrete pneumatically projected at high velocity onto surfaces. It often includes accelerators for rapid setting and requires no traditional formwork.

   2. Construction Methods

   ① Concrete: Mixed on-site, poured into formwork, and cured over days. Suitable for standardized structures like beams and slabs.

   ② Shotcrete:

   ①  Dry-mix: Dry ingredients are mixed with water at the nozzle, allowing longer spraying distances but generating dust.

   ②  Wet-mix: Pre-mixed concrete is sprayed directly, reducing dust but requiring specialized equipment.

   ③  Advantages: Adapts to irregular surfaces (e.g., tunnels, slopes) with minimal rebound when reinforced with mesh.

   3. Material Properties

   ① Concrete: Offers broad strength grades (e.g., C20–C60) and high durability for static loads.

   ② Shotcrete:

   - Smaller aggregate size (typically ≤20mm) and accelerators ensure quick hardening.

   - Higher density improves impermeability and crack resistance but increases costs.

   4. Applications

   ① Concrete: Foundations, columns, pavements, and other standardized structures.

   ② Shotcrete: Complex geometries (tunnel linings, slopes) and urgent repairs (structural rehabilitation).

   Shotcrete is a "dynamic" variant of concrete, ideal for complex or urgent projects due to its spray-applied technique and rapid setting. Traditional concrete remains optimal for standardized, high-volume construction. Choose based on project complexity, timeline, and budget.