Necessitation of the maintenance
The causes which necessitate the maintenance effects the service and durability of the structure as follows:
ü Atmospheric Agencis
ü Normal wear and tear
ü Failure of structure
1 Atmospheric Agencis
Rain: It is the important source of water which affects the structure in the following ways:
Expansion And contraction
ü The material is subjected to repetitive expansion and contraction while they become wet and dry and develops the stresses
ü Dissolving and carrying away minerals as it is universal solvent
Chemical: The water available in nature contains acids and alkali and other compound in dissolved form acts over the material to give rise, which is known as chemical weathering.
i. Wind:It is the agent, which transports the abrasive material and assists the physical weathering.
ii. Temperature: The diurnal, seasonal and annual variation of the temperature, difference in temperature it causes expansion and contraction.
2.Normal wear and tear
During the use of structure it is subjected to abrasion and thereby it looses appearance and serviceability
3 Failure of structure
ü Improper design- Due to incorrect, insufficient data regarding use, loading and environmental conditions, selection of material and poor detailing.
ü Defective construction-poor materials, poor workmanship, lack of quality control and supervision.
ü Improper use of structure- overloading, selecting the structure for the use they not designed impurities from industrial fuel burning, sea water minerals etc.