Chemical grouting is not about smearing mortar over a wet crack (which inevitably fails). It is a process of injection.

The primary material used is Polyurethane (PU) Resin.

When this liquid resin meets water, a chemical reaction occurs instantly. It expands (foams) up to 20-30 times its original volume, hunting down voids and solidifying into a watertight seal.

The Two Main Types:

• Hydrophobic Grout (The Shield): Repels water. It reacts with the water present to form a rigid or semi-rigid foam. It does not shrink over time and is ideal for filling voids behind the manhole wall.
• Hydrophilic Grout (The Sponge): Absorbs water. It turns into a flexible gel. While excellent for cracks that move, it requires a moist environment to stay swollen and sealed.

Method 1: Crack Injection (Drill&Pump)

Target: Visible cracks, pipe penetrations, and joints.

This is surgical precision.

Drill: A hole is drilled at a 45-degree angle to intersect the crack deep inside the concrete wall.

Port: A mechanical packer (injection port) is hammered into the drill hole.

Pump: High-pressure resin is injected. It travels through the crack, reacting with the leaking water, and expands to fill the fissure from the inside out.

Best For: Sealing specific, identifiable leaks in precast joints or wall fractures.

Strategic Use: The "Pre-Hab" Step

Smart engineers rarely use grouting as the only solution. It is the critical "Step 0" of a rehabilitation plan.

• Grout First: Stop the active infiltration and stabilize the soil behind the wall.
• Prep Second: Now that the substrate is dry, you can sandblast and clean it.
• Line Third: Apply your Epoxy, Cement, or CIPM liner to a dry surface for a permanent bond.

Note: If you try to spray epoxy over an active leak, you will get bubbles, pinholes, and immediate failure. Grout is the insurance policy for your liner.

Method 2: Curtain Grouting (Encapsulation)

Target: Brick manholes with water coming from everywhere.

When a brick manhole is "weeping" from every mortar joint, drilling 500 holes isn't feasible. Instead, you grout the soil outside the manhole.

• Drill Through: Holes are drilled swiftly all the way through the manhole wall into the surrounding earth.
• Saturate: Large volumes of grout are pumped into the soil surrounding the structure.
• The Curtain: The grout mixes with the soil and groundwater, forming an impermeable "gel curtain" or shell around the entire manhole exterior.

Best For: Old brick assets with disintegrated mortar or high hydrostatic pressure.

Stop the Flow Today

Don't let clean groundwater steal your treatment capacity. Chemical grouting is the fastest ROI maintenance activity you can perform.

Need a Grouting Specialist?

This requires high-pressure pumps and specific safety training. Find certified applicators in our directory.