Cracking

Short- and medium-term consequences

Not to mention the noise and sensory nuisance of a wheel in contact with a crack, there are notable consequences resulting from the presence of cracking on pavements:

• Decrease in pavement service life
  Premature wear and tear, structural failures
  
  
• Awareness of climate phenomena
  Freeze/thaw, precipitation...
  
  
• Increased danger to motorists
  Variable adhesion
  
  
• Traffic disruption
  Areas of cracking and deterioration that can cause users to brake due to a lack of comfort or perceived safety.

In this context, Texum has developed innovative solutions, specific to each type of road structure, aimed at eliminating cracking phenomena while reinforcing the pavement structure.

Following the appearance of cracks, associated (or not) with wear and tear on the road surface, a repair operation of the wearing course is often the most appropriate solution to rehabilitate a pavement in a simple and economical way. However, the implementation of this solution can be degraded very quickly by reflection cracking phenomena.

This reflection cracking, more commonly referred to as cracks, is caused by the propagation of an existing crack in a structural layer below the wearing course (base and/or binder course). Without careful consideration of this parameter, the new tread will deteriorate as soon as possible.

The loads applied to road structures are defined in accordance with the rules of cyclical application, resulting in mechanical wear phenomena to be taken into account over considerable periods of time.

When dimensioning a pavement, a traffic load is defined (associated with other parameters) in order to establish the road structure according to current standards.
During the pavement life cycle, vehicle density may increase. In the event that this event occurs, the structure absorbs more load cycles than initially expected, and is therefore the result of a phenomenon known as fatigue, prematurely.

To this is added the phenomenon of ageing of the asphalt mix forming the wearing course. The oxidation of the binder reduces the cohesion of the material, making it more rigid and especially more fragile: the pavement is then very sensitive to cracking.

Fatigue cracks have an evolutionary process similar to shrinkage cracks, but they differ in that they generally occur in the longitudinal direction. These cracks can affect all layers of the structure or be confined to the wearing course.

For the same applied load, an asphalt mix will vary in resistance to deformation depending on the temperature. Despite the choice of asphalt mixes according to their thermal properties (curing and softening temperatures), they are sometimes exposed to unpredictable weather and thermal stresses..

Consequently, when subjected to mechanical stress at too high a temperature, an asphalt mix - known as soft asphalt - may deform irreversibly under load.
As a result of these deformations, cracking problems can occur because the asphalt thickness is locally modified.

Conversely, the bituminous asphalt mix is stiffened, directly linked to the drop in temperature. When subjected to mechanical stress at too low a temperature, asphalt mixes tend to work under stiff conditions. This more rigid mix will accentuate the phenomenon of thermal cracking by its increased fragility.


Concrete, on the other hand, remains sensitive to temperature variations. Under the action of the cold, these materials contract, resulting directly in the initiation of thermal shrinkage micro cracks. Even if the type of concrete used and the thickness of the layer considered directly influences the shrinkage rate, any layer (of road structure) composed of concrete is subject to thermal cracking