What is deterioration/decay

Deterioration 

After a particular age and due to lack of maintenance, defects in a structure develops. If these defects goes on increasing due to lack of maintenance, the compounds of mortar and concrete decomposes making the concrete weaker .
In maintenance engineering, the Deterioration is defined as "The continuous degeneration of structure and its components which render it unusable,"

Factors causing deterioration

Deterioration or decay of structure seems to be a simple process but actually, this is a very complex phenomenon. Many different types of reactions take place while decaying of structure. This (deterioration/decay) of structure can be due to a single or combination of different types of factors.
Factors causing deterioration are -

• Human activities
• Chemicals attack
• Environmental agencies
• Lack of maintenance
• Other miscellaneous activities

Human activities - 

Mostly deterioration of structures is due to human activities. These activities include lapses at construction stages, inadequate use of the building, etc.
Actually, most people do not care about public buildings, they make impressions on the surface of building by scratching, do improper activities just to harm the building and many more disgusting activities. Only because of this health of building disturbs.

Chemical attack

This type of attack (Chemical attack) is mostly seen in structures that are surrounded by a polluted environment. Polluted environment contains various poisonous chemicals that react with water and forms acid, which then falls in the form of acid rain. Due to acid rain,, the compounds of structure (cement, steel reinforcement etc) lead to disintegrating, losing color, softening, corrosion, etc. 

These chemicals also directly attack the structure by other medium air.  

Environmental agencies

Various environmental agencies like sun, water, air, rain, groundwater, ground salts etc attack on components of structure leading to the deterioration of the building. 

Other miscellaneous activities

Following are some main miscellaneous activities that are responsible for the deterioration of building -

• Poor construction materials
• Bad workmanship
• Poor design
• Misuse of building
• Poor budget