Cracks in the walls, because they are formed and when to worry

The presence or appearance of cracks in the walls of a building – both widespread that localized – It is a common situation, especially if the structure has been in operation for several years. In fact, this situation represents a real Pathology of instability for the building. The birth of one or more cracks is nothing more than the explicit manifestation, by the structure, of a possible resistance deficit: position and extension, as well as thickness of the same crackidentify the possible presence of structural problems more or less severe. However, in many cases we have to do with degraded elements only superficially, whose “damaged” condition does not affect the static of the entire building or, possibly, of a limited part of it. Study its genesis, in the most severe cases, is the first step for the determination of the most effective intervention methods, aimed at restoring or improving expected performance.

Cracks and cracking: the main causes

The phenomenon we are analyzing is that of crackwhich takes place when generating a discontinuity within a solid body. Discontinuity is formed because the body is unable to resist the agents’ stresses, which would therefore like to overcome the maximum resistance of the material in some point. To this discontinuity is given the name of cracks, or lesionwhich is the technical term that is replaced by that of crack, more commonly used in daily language. The set of all the injuries that belong to a building organism identifies what comes technically called crack: represents the starting point for it study of the causes of the instability of a building, or structure in general. The single crack, in fact, is the materialization of a crisis of resistance of the material whose element is made up. The behavior – mainly fragile – is characterized, in the most common cases, by limited resistance towards traction efforts. Therefore, an injury always manifests itself in the orthogonal direction to that in which qualitatively the material is “pulled”.

Wanting to summarize, a cracking picture can substantially be generated by the following causes:

• Natural events of various types, both important and modest entity. It is worth distinguishing Severi eventshow it could be an earthquake, from Less severe events But still important, as the seasonal variations of temperature could be, the progressive degradation of materials over time and the atmospheric agents who interact daily with the elements.
• Setting of the earthly foundation system. These can develop in a short time or even very long and can also be conditioned by seasonality, as a result of the natural changes of the subsoil level level.
• Design or constructive errors, or significant variations over time of conditions of use of the structure.

It is clear that the actual cracking picture could easily generate from a contributing factor of all the factors exposed here.

The cracking paintings in the structures in the ca: how to understand when it is dangerous

For buildings designed with a supporting structure in reinforced concretethe problem is usually limited to the cracking of plaster or to the injuries of the buffer walls. The cracking of the plasters, although not dangerous from the static point of view, is an indication of the Training of weaknesses in the protection layer from atmospheric agents. The cause of these lesions is to be found usually in the phenomena of withdrawalthat is, the contraction of the material during the hardening phase. In other cases, the phenomenon may have been triggered by one bad laying of the material or one incorrect choice of the type of plaster, In relation, for example, to the environmental conditions present.

The lesions to the buffer walls They already manifest themselves with a more accentuated fraud and tend to be an indication of more serious problems than those described above. In many cases, the problem is to be found in differential sagging of the foundation lands (when the cracking is sufficiently extended on a facade or concentrated in some edges), or in the lack of appropriate load -shaping systems In the presence of holes (in this case, the cracking framework develops near the opening in the wall).

The presence of a state of cracking on supporting structures such as beams and pillars instead he must arouse particular concern. The cause could be associated with an important evolution of soil sagging (it follows that the walls will also be severely damaged) or to exceptional natural events, such as an earthquake. However, the cracks produced by the CALCESTRUZZO RETROM or from the presence of corroded armor. Nonetheless, in these cases it is appropriate that a technician carry out a detailed evaluation of the state of the places, to evaluate any static problems of the building.

The cracking paintings in the load -bearing masonry structures and the earthquake injuries

In the structures made with bearing walls, that is, with brick walls or stones that perform a primary structural function, The analysis of the cracking picture is much more complicated. In these cases you can find yourself with widespread injuriesof nature and variable extension – in many cases even in different points of the building. The importance and severity of the cracking picture is very dictated by theamplitude of the injury and its extension. In fact, the structure could find a new balanced and safe configuration even in the absence of a solid continuity at every point of the wall. However, some injuries may instead be a symptom of important structural deficiencieseven until they lead to the birth of cinema unwanted (real reversals of a wall) that can significantly compromise the static of the building.

In addition to any sagging in the foundation, the causes of the birth of pronounced cracking paintings in wall structures are to be found in the changes and variations in use of the building, succeeded in time on the same during the years of use. Seismic events are a further cause of the birth of lesions in bearing walls: in damaged structures due to an earthquake, it is possible to notice in a pronounced way a crack with a typical X shapeindex of the cyclical behavior expressed by the building during the seismic event.

The control of the trend of the lesions

Among the techniques often used for the control of the trend over time of injuries, there is the so -called use of crackeven vulgarly called showcases. The test, in essence, is based on the insertion of a device at the turn of the crack, solidarity with the bodies affected by the injury and arranged with an almost direction almost orthogonal to that of formation of the injury itself.

The insertion of the showcase allows you to understand if the crack continues to open up or is found in a stationary situation. It is not only important to know whether this continues or not to increase by amplitude, but also with what speed it does so. The showcase is equipped with a graduated scale that allows a reading of the advancement of the movements relating between the two walls of the wall: if the movements are excessively large, The showcase can even be brokenand this therefore provides a counter -proof of the non -stationarity of the phenomenon.