Treatment of fissures in concrete walls

Fissures in concrete walls could be caused by water infiltration and possible structural degradation, due to which treatment thereof is necessary.

These fissures or cracks are classified according to dimensional stability: if stabilized they are called passive fissures, whereas if they are still forming they are called active fissures.

Preliminary analysis

Firstly, we must evaluate the type of fissure we are going to treat:

  • Passive or inactive fissures:

Those which are not subjected to any type of movement.

  • Active fissures:

Those still affected by some type of movement.

To see the type and development, it will be determined based on a gypsum plaster probe on the fissure.

When this probe becomes fractured, it is an active fissure.

Technical considerations

Passive or inactive fissures:

In turn, there are two types:

  • If the fissures are located on the concrete surface (the maximum depth of which is that of the framework coating itself):
    • We will firstly proceed to open the fissure in a V-shape using a radial arm saw.
    • Next it is cleaned, moistened and filled with a repair mortar of the GECOL Reparatec range, depending on whether they are aesthetic or structural repairs.
    • Finish floating or smoothing.
    • After 24 hours have elapsed a coating mortar can be applied.

If the framework is exposed: see “Structural concrete repairs.”

  • If the fissures are propagated throughout the thickness of the concrete structure and affects it, from the physical-mechanical viewpoint, they must be treated as a structural degradation.

This procedure will be limited to passive fissures that do not have variations in size (longitudinal and/or crosswise).

The procedure will consist of the injection of reactive epoxy or polyurethane resins: bicomponent epoxy resin (if the substrate is dry) or bicomponent polyurethane resin (in the presence of humidity).

This system allows the subsequent application of a hydraulic waterproofing mortar of the GECOL Imper range, according to the required technical characteristics.


Active fissures:

They will be repaired, depending on the type, as follows:

  • Fissures with movement of up to 1/3 with respect to their initial width will be repaired by applying a flexible or elastic coat.
  • If the fissures have movement superior to the previous, will be considered movement joints and, as such, will be treated with elastic sealants such as GECOL Elastic-MS, and shall not be sealed with rigid coatings.

Recommended products

Concrete repairers



Structural-fast setting


Fast setting

Thin layer 3 mm Elastic

Thin layer from 2 to 5 mm

Thick layer 10 mm


Flexible mastic

Elastomeric mastic

Warnings: The data provided by this Constructive Solution were prepared based on standard onsite installation processes. However, we recommend that you consult our Technical Department in the event of any specific circumstance