Curtain injection and structural

Curtain injection and structural injections are trenchless, advanced technologies for restoring or repairing the waterproofing of buildings. It is used in situations where traditional excavation of foundations from the outside is impossible, uneconomical, or hindered by dense urban development. When performed correctly, this procedure effectively protects the underground parts of buildings, basements, tunnels, and shafts from moisture and groundwater from inside the structure.

What are curtain injections and structural injections?

These methods involve injecting sealing materials into the structure of the partition (structural injections) or directly behind it, into the surrounding soil (curtain injection), without the need for earthwork.

The main reasons for using these methods:

Absence of original vertical or horizontal waterproofing, natural deterioration of existing protective measures, inability to excavate externally, persistent moisture in the partitions, and capillary rise of water in the walls.

Classification of technologies based on their nature:

Depending on where the material is applied and how the structure is sealed, we distinguish between:

• Curtain injection —involves drilling a grid of through-holes in a wall or floor and injecting material into the ground, where it forms a continuous, external curtain (barrier) that keeps water away from the structure.

• Structural injections (volume injection) – involves densely saturating the interior of the building material itself (e.g., porous concrete or brick), which blocks the pores, completely displaces moisture, and fully seals the partition.

Important: Accurate assessment of the material’s technical condition and porosity is essential for selecting the appropriate technology, drilling geometry, and injection pressure parameters.

Selection of grouting materials

In curtain and structural technologies, low viscosity and high penetration are key, which is why specific binders are used:

• Acrylic gels: Most commonly used for curtain injection and structural sealing; due to their water-like viscosity, they bond exceptionally well with the soil and form a highly flexible, durable membrane resistant to groundwater.

• Silicates, creams, and silicone microemulsions: Commonly used for structural capillary injection in masonry to create a horizontal barrier that effectively blocks the upward movement of moisture in the building.