Concrete is an extremely stable and durable material, but it is not an unbreakable one. For several reasons such as natural forces like thermal expansion (freeze-thaw phenomenon) or poor construction design, failure of concrete making or overloading, active or dormant cracks are created. These kinds of active cracks need to be first appointed and then repaired in order to address any stability and to protect the waterproofing membrane that will follow.

Although hairline cracks can be accommodated by the flexibility of the HYPERDESMO® System’s polyurethane waterproofing membranes, bigger cracks that are formed by continuous movement are crucial to be repaired in order to prevent their transmission to the waterproofing membrane which will cause raptures.

The first step is to observe and analyze the crack movement in order to decide the appropriate repair method. The test can be taken by using a rigid but non-shrink material to bridge the surface of the crack.

In case there are not any expansion joints installed to accommodate the tensile strength of the structure’s movement, it is strongly recommended to carve them prior to any installation.  A correct design of joints is required for the long-term performance and longevity of the system.

The benefits of flexible polyurethane sealants in active cracks for controlled movement.

Regardless of crack width, polyurethane sealants are suitable for the treatment of small or larger cracks ad they form a permanent, tough and elastic seal.  Moreover, they satisfy the major requirements for crack filling by being fast curing and having strong adhesion, strength, high elongation properties, good workability, stability and long-term performance. ALCHIMICA’s advanced polyurethane technology sealants offer excellent bonding to clean concrete.

How to apply

Opening the crack
Cracks smaller than 5mm need to be opened manually at a minimum width of 5mm

Substrate preparation
The edges should be sound and clean from any grease or oil contaminants and a vacuum cleaner should be used to removing any dust.

Application of HYPERSEAL sealants
Using a caulking gun and with nominal pressure the sealant, fill the crack.
Slightly excess amount should be applied for tooling and finishing purposes.

Finishing and cleaning
The sealant should be tooled immediately with a spatula by pressing against the joint to remove air pockets and to ensure 100% contact and adhesion with the surface.