Why cracks appear on the building and can they be eradicated forever?

Cracks on the building are nightmare for few and source of discomfort for many. What is the reason for their occurrences? Why do they re-occur even after repairing the building so well? Can they be removed completely? Are they dangerous?

The modern concrete structure is blessed with alarm before any mishap takes place. The concrete structure always gives signals before it comes down. It is for the human to take notice of these signals and act in time. In case of collapse of a building most of the time human factor is responsible for the calamity. In the modern structure RCC frame work is the main element for holding the building in a place. Principles of arch are applied at every stage and this chain of arches is the key factor in the whole edifice. The traditional arches may not be seen here but they are there with the help of supporting members like columns, beams, slab etc. Together they form a RCC grid. All know that in an arch if any one support is removed, then the whole arch collapses. In the modern building disturb one column, slab or beam and the whole building will go in a state of dilapidation.

Then cracks must be dangerous!
The cracks appear for various reasons. There are different types of cracks and all cracks are not dangerous. However these cracks cannot be neglected, because they can turn the situation in to an alarming condition. Any crack on the building is like a ruptured skin of our body. The water enters into the structure through this crack and initiates deterioration of the building. When water reaches the core section it creates serious damages to the RCC frame work and these damages are not reversible. One can never bring a repaired building to its original status.

Crack on the building surface is one of the indicators stating that there is some problem. But does it mean that all the cracks indicate that the structure is damaged? Yes, they do indicate that all is not well. Therefore the regular timely maintenance of a building is imperative for the durability and stability of the structure. Most of the cracks can be repaired or it is possible to check their progress.


Can they be avoided?

The R.C.C. structures are in-separable from the problem of occurrence of the cracks. Every thing has defined period of life, structure is not an exception to this rule of nature. It has an extinction program which starts with small hair line crack, then visible crack, then a wide crack, then fissure and so on. In spite of using best of material and skills and taking all the possible care during the time of construction or during the repairs of a building, cracks do appear on the surface, in the course of time. They appear during the construction process and thereafter during the service rendering period of the structure.


Types of cracks

Generally the cracks are classified as structural and non-structural cracks. When the negligence persists, a non-structural crack invites structural cracks. The structural crack has to be attended on priority, in the interest of the stability of a structure. It is a job of an expert to decide upon the categorization of the crack. It requires experience and thorough consideration of the factors affecting the structure and initiating the destruction phenomenon in the building. Detail knowledge of the structure, the pattern, location, depth, inclination of the cracks is essential to asses the damages correctly.


Is it possible to check their progress?

It is possible to reduce formation of the cracks and to arrest their growth by timely corrective actions. The cracks (other than structural) in the initial stages are not dangerous. They become a matter of concern when they are widened and allow corrosive substances to enter the inner core of the structure, the reinforcement. Ingress of water molecules and the other chemicals in the form of fumes or gasses react with surrounding and change the chemical composition of the concrete and steel, thereby make it weak and feeble. Rusting of the steel reinforcement is termed as cancer of the structure. The treatment is expensive and time consuming. The damages caused to the structure cannot be attributed to a single cause initiating the cracking process. It is a resultant of the complexity of the cracks formation fundaments.

Negligence to-wards an insignificant minor surface crack can lead to a major repair job project, over the period. Such repairs involve lakhs and crores of rupees depending upon the extent of damage and the size of a building. “A stitch in time saves nine” is very true as far as cracks on the buildings are concerned. Delay in taking proper remedial measures lead to the increase in the damage to the structure and escalation in the repair cost.

Sealed the crack, filled the gap Still, why the wall is damp?

While answering a telephonic call, I heard a man saying “Sir, my building has grown mustaches all over, will you please advise us on how to get rid of them?” I never had an occasion to treat such a problem. After taking a discussion little further I was enlighten on the agony of the man. It was appreciable of him that even at the movement of tremendous irritation and discomfort the man had not lost his humor.

The cause of his excitement was that, that he being one of the office bearers of a housing society, had got all the visible cracks on the exterior surface of the building, filled in, to prevent the leakages in the flats of the members. But the leakages had not stopped; the entire building was covered with crack filled strips and was looking awful and ugly. The poor man had to listen to the comments of the suffering members whenever they met in the building premises, regardless of time and occasion. On meeting this gentle man the people had no other subject to talk but the leakages, ugly face of the building and waste of money and the efforts.

This incidence is mentioned because the approach amused me, but the experience of this type is not uncommon. While moving in the street we see several such buildings and certainly the site is not pleasant to feel good of it. If we understand the leakage problem then perhaps we may not attempt to experiment of its kind on our own building. Getting such a treatment done on a building is nothing but fooling oneself, wasting our hard earned money and whiling away the time.

The exterior wall surface of a structure is subjected to harsh treatment from the elements during every passing time, 24X7. It experiences cold during night and winter season, faces burning heat during day time and in the summer season and gets non-stop beating from the ruthless rain showers in the rainy season. Though the cold is moderate in our part of the world, the heat and the rain are intense. The attack is more on the facing side than on the shadow side that is mainly in the south west direction. In case the building design provides a plane wall in this region then the leakage is much more sever to bear.

The constant variations in the temperature initiate cracking of the surface. It starts with the pin holes or hairline cracks and ends up with fissures if neglected for long. We should understand that this is a natural process of deterioration of a building. Nothing is permanent in the world, so is our building. These tiny little cavities hold water which was provided by rain and throw it out in the form of vapour in the October heat. With every passing season the cavities grow deeper and the intensity of the formation of crack increases. Constant repetition of the phenomenon makes the surface absorbent and carries water in the core section of a structure. When the water appears on the inner wall surface we say that leakage has started, however in the reality the process had commenced much earlier and over the period the water has travelled through the wall thickness and has appeared on the inner wall surface. The gravity of the problem depends upon the extent of the damages caused to the exterior surface.

One should not wait for leakages to appear, to prevent the damages to the structure. The damages to the structure are irreversible and a damaged structure cannot be brought back to its original status. So it is better that the preventive action is taken before any losses occur.

When we study the construction process of a building we find that it was not constructed in one go. There were number of stages in the process and the activities were on hold on many occasions. This had formed construction joints which perpetually remain open. We also note that the outer surface of a building is not monolithic but it is formed in layers. So the construction joints, sharp corners, layers of plaster etc. provide lot of room for water to enter. It is very difficult to locate such spots and to treat them accordingly. Such vulnerable places could be anywhere in the structure. Water when enters the structure body it travels vertically, laterally and sometimes even rises to unimaginable heights. This water again appears on the inner surface in the form of damp patches by breaking weak barriers. By now it is quite clear that the entry point and surfacing point of water may not be the same, and that is the reason why local treatments are not successful, even after using best of waterproofing materials. To make the structure waterproof it is essential that the entire exterior surface is properly treated after considering the movements in the structure and critical areas.

In case of our gentleman in trouble, the building is treated at the visible cracks, but no work is done on very small tiny holes and hairline cracks. Also nothing was done at the junctions and the corners. So much of the area remained as untreated and therefore the surface had still lot of entry points for water to get in and the problem continued. It is therefore imperative to treat the entire surface of a building. In the treatment any one type of material may not suffice and so the various formulations may be used as per the requirement of the critical areas to get the satisfied results.