Expansion joint repair and sealing

We seal and repair expansion joints in poorly maintained concrete floors and offer a better solution with BECOSAN® polished concrete.


We perform repairs and sealing of expansion joints on concrete floors. This is a precursor to a treatment with our patented BECOSAN® system, where we harden and seal the concrete floor to minimise future damage.


Expansion joints in a concrete floor are a principal cause of deterioration of a concrete floor. It is important to repair these joints as soon as damage is detected to prevent further deterioration and disruption.

We recommend sealing these expansion joints immediately after a concrete floor has been laid, although we recognise this is not always the case. Through intensive use the edges of the joint begin to wear and can become a safety hazard for workers.

Timely repair of expansion joints will extend the life of your concrete floor.

Contact us for more information.
Sellado de juntas con resina
arreglo de fisura hormigon


Expansion joints allow for expansion and shrinkage of blocks of concrete. They also prevent friction between adjacent blocks.

In industrial flooring, they are known as expansion joints because they regulate compression deformations in the concrete. These are caused by internal expansion, caused by thermal variations, load fluctuations, or movements of the concrete mass.

Junta de Dilatación en pavimento

These joints are designed to avoid the structural alteration of the reinforced concrete elements.

In addition, expansion joints provide mutual insulation between the concrete elements.

Concrete and reinforcing steel have similar coefficients of thermal expansion. They are exposed to thermal variations and both steel and concrete react collectively. The impacts of these variations are absorbed by the expansion joints.

Concrete expansion joints can be either Open or Sealed:

Open joints

These are unsealed joints, which makes them especially susceptible to the accumulation of particles and dirt, deteriorating rapidly if they are not maintained periodically.

These joints result from the calculation of the amount of the expansion possible in the construction material.

The exposed edges of the joint can crumble through heavy use creating dust.

Sealed joints

Sealed joints are the opposite of open joints. The open joint is filled with an elastic and waterproof  material. They are, therefore, resistant to humidity, temperature variations and erosion. They also reduce the amount of dust created by eliminating exposed edges.

Juntas de dilatación selladas


The main function of expansion joints is to prevent random, unsightly, unpanned cracks appearing throughout the concrete structure.

Expansion joints are either planned before the concrete is laid, Construction Joints, or are built into the concrete after it is laid, Contraction Joints.

Construction Joints are planned before the concrete is laid. It is made by placing a bulk head, usually made of wood or plastic, in the precast concrete. These bulk heads are often used as a guide to the finishing scree of the concrete. Once the concrete is set the bulk heads are removed.

Contraction Joints are made in the concrete after it is laid and has set (but before the concrete is cured). They are cut into the concrete using a Concrete Saw.  Knowing the concrete will crack due to temperature variation and load placed upon the concrete, the Contraction Joint is basically a groove cut into the concrete to direct where the crack will occur.


Like any other structural element, isolation joints of a concrete floor are subject to progressive degradation over time. This leads to the expected wear, which in turn requires measures to repair expansion joints.

Desgaste Juntas de dilatación en hormigón

Most damage is caused by abrasion.

The following types of abrasion are present in concrete joints:

Abrasion by traffic

This is caused by the friction of different transport vehicles on a floor. The joint resistance of a rigid floor depends on the characteristics of the used sealant. If the sealant is weak, wear by abrasion will lead to the formation of cracks and fissures, compromising impermeability.

Abrasion by erosion

Wind-blown sand particles impact the surface of the joints. In most situations wear from wind is very low, however, it depends on the environmental conditions.

Abrasion by chemicals

Finally, we have the abrasion given by the interaction with chemical agents, such as some aggressive cleaning products. These can weaken the molecular structure of the sealant, causing it to disintegrate, exposing the structural elements to further wear.

Abrasion by footfall

In Expansion Joints that have not been sealed abrasion by footfall can be significant. Where the boot comes in contact with the edge of an expansion joint that edge can crumble and create dust.

At BECOSAN® we believe that all expansion joints should be filled.



If left unfilled expansion joints will fill with dust and debris so clearly we must fill the joint, but with what?

Obviously, because the joint moves it must be filled with a flexible, elastomeric, material. There are many different options but here at BECOSAN® we use a Polyurea based filler like the ASTC 3246 Polyurea Flexible Joint Filler.

Grietas en junta de dilatación

The filler comes as two liquids which are mixed together under pressure as it is being injected into the joint. The filler is highly liquid and is self leveling. As it dries it expands and needs to be trimmed to the level of the concrete once it has dried.

At BECOSAN® we believe that concrete can be beautiful so colour matching of the filler to the concrete is important. A dye can be added to the filler so that it matches perfectly.


Solar radiation influences joint wear. Ultraviolet rays in particular alter the elasticity and plasticity of sealant substances. Due to the long exposure period they become stiff and unable to absorb friction and reduce deformations.

Expansion joints should be inspected regularly. Every 3 to 6 months. In tough industrial and commercial environments the filler can become dislodged and overtime the filler will lose its flexibility and will come away from the wall of the crack. When signs of damage and wear are revealed it is time to replace the filler.

The old filler is removed using a concrete saw. Once removed the joint can be vacuumed and a new filler can be applied.

Through use the concrete itself will begin to disaggregate creating dust and making the floor unattractive. This is the time to apply the BECOSAN® System to grind, harden, polish and seal the concrete floor making it cleaner, more beautiful and longer lasting.