First establish the repair objective
Distinguish three tasks: temporarily stopping a leak, permanently sealing a crack and restoring force transfer. Each requires different material selection and result assessment. With intense water inflow, stopping the leak may be the first stage before the main sealing.
Try to establish the cause of cracking and check whether it remains active. Filling the crack alone does not eliminate its cause. If the fissure moves, the seal must remain watertight under the expected movement. Where rigid bonding is the objective, the solution should be selected according to structural repair requirements.
What to check before selecting a material
Record the crack path and width at several points, the element thickness and surface access. Define water conditions: dry, continuously damp, intermittently damp or active water inflow. Where leakage occurs, assess its intensity and whether it changes over time.
Check whether the crack width changes. Assess concrete condition at the edges, contamination and loose fragments. Account for reinforcement locations when planning boreholes. A few trial points allow verification of fissure intersection and material communication before work starts along the entire section.
Water and crack movement in resin selection
CrackFlex cures chemically and does not need water to react, making it suitable for sealing dry cracks and cracks that dry intermittently. WaterStopper and EasyInject react with water. HydroGum also needs water contact; for dry cracks it can be injected in a two-component arrangement with water at a ratio of 1:1, according to the product method.
For a moving crack, the seal's ability to deform and retain adhesion matters. The material's elongation at break alone does not define the allowable movement of the entire repair. EpoxPower forms a rigid bond and serves a different purpose from flexible sealing with CrackFlex.
What must the material do in the crack?
Select the objective and check the function expected of the material.
Permanent sealing
The objective is lasting watertightness. For a moving crack, the material must retain adhesion and deform with the fissure within the range specified for the repair.
Temporarily stopping a leak, permanent sealing and restoring force transfer are three different repair objectives.
Material selection for the repair objective and conditions
Select a material suitable for the repair objective, water presence and crack movement. Then check application conditions in the technical data sheet and confirm the procedure on a trial section.
| Identified situation | Selection approach | What must be confirmed |
|---|---|---|
| Dry, stable crack; rigid bonding required | EpoxPower epoxy resin | Adhesion, surface condition, moisture permitted for the system and structural requirements. |
| Dry, damp or wet crack; flexible sealing | CrackFlex two-component PU resin | Movement range and adhesion; with water under pressure, the need to stop leakage first. |
| Intense water inflow; temporary leak stopping | WaterStopper — hydroactive foam for the preliminary stage | Water availability, reaction in the trial and feasibility of subsequent main injection. |
| Damp zone; filling with sealing foam | EasyInject one-component PU resin | Reaction conditions and the need for a second, permanent sealing stage. |
| Wet crack, or dry crack with controlled water injection | HydroGum one-component PU resin | Water contact required for reaction; in dry cracks, a 2K arrangement with water at 1:1 and suitable equipment. |
| Fine water paths; adjustable gel time required | AcrylGel + Polymer acrylic gel | Service moisture conditions, volume changes, variant with polymer or water and a system-compatible pump. |
Preparing material and equipment
Before mixing, check component ratios, allowable temperature and material working time. Distinguish mixture pot life from reaction time and full curing time. Prepare only as much material as you can inject before its pot life ends.
Match the pump and injection method to the product. For HydroGum with water and AcrylGel with water or polymer, follow the selected method variant. Do not transfer ratios or parameters between different sets.
Before starting work, also prepare a cleaning agent and plan equipment flushing during breaks. Personal protection and component handling requirements are given in the safety data sheets (SDS).
Active leakage and moving cracks
If intense water inflow makes sealing difficult, first stop the leak with WaterStopper. Then carry out the main injection with CrackFlex, which forms a flexible seal. Stopping water after the first stage does not mean the whole repair is complete.
Before the second stage, check that further material injection and communication between packers remain possible. Match subsequent injection timing to the system used and working conditions. The solution's durability also depends on identifying the cause of cracking and the range of crack movement.
What to observe during injection
Observe resin reaching subsequent packers, discharges at the crack face and material consumption. A sudden pressure rise without communication may indicate a blockage or a borehole that misses the crack. High uptake without visible progress may indicate material escaping beyond the repair section.
If behaviour is unusual, stop injection and check the cause. Do not assess filling solely from the pressure gauge. Record points between which communication was observed and locations requiring re-injection or further assessment.
How to check the repair result
After the material cures, inspect the repaired crack and its surroundings. For sealing, check that water does not reappear under the pressure encountered in service. If leakage was intermittent, repeat the inspection when those conditions recur.
For structural repair, confirm the required filling and bonding according to the design. Keep records of the material used, borehole layout, consumption and observed communication. Mark locations where filling could not be confirmed.
Documentation and tools
Check material properties and limitations in its technical data sheet. Safe working procedures follow the relevant safety data sheet and equipment instructions.
Need a safety data sheet? Contact us. Request an SDS →