Achieving Durability of Concrete Structures:
The durable concrete structures are to be conceptualised, specified, designed, contracted, constructed and maintained. To achieve the design life of the structure at reasonable maintenance cost, the following aspects are required to be taken care of:
i) The structure should also be designed for environment loads and detailing done.
ii) Selection of proper construction materials.
iii) The concrete should be impermeable, with designed crack width due to shrinkage, thermal forces or loads.
iv) The good construction practices should be followed.
v) Selection and application of correct coatings to reinforce bars and concrete surface.
vi) Planned maintenance.
vii) Proper specifications.
1. Environment loads such as wind loads, snow loads, earthquake loads, tsunami loads etc. to be considered while designing the structure. The effect of type of environment should be considered in design as per respective design codes and suitable cover to reinforcement shall be considered and proper concrete mix should be designed.
2. Proper selection of construction materials should be done for construction of durable concrete structures. Proper selection of cement, sand, aggregates, admixtures and water etc. should be done to make concrete structure durable.
3. Proper consolidation of concrete, proper alignment of shuttering, proper concrete mix and water cement ratio shall be done to ensure that the concrete is impermeable. Impermeable concrete have more life because it reduces the corrosion of reinforcement steel embedded in it.
Where there is difference is temperature on top and bottom surfaces of concrete or concrete subjected to higher temperature during use, thermal stresses shall be considered in design.
4. Standard procedure for construction of concrete structures shall be followed to reduce the construction errors at site.
5. Use of epoxy coated reinforcement are suggested by design codes for critical environmental conditions such as structures near coastal areas. These must be followed and reinforcement must be properly coated with suitable material as specified in relevant codes.
6. It is required to follow the standard specification for the concrete construction and maintenance, so that materials selected, procedure for execution, pre-concrete, during concreting and post-concrete checks are followed. Standard repair and maintenance specifications shall be used to reduce the damage risk due to any site error.
7. After the structure is put into use, proper and timely maintenance of structure is necessary to maintain the strength and durability of concrete. So, the maintenance schedule shall be planned and prepared and shall be executed to prevent damage risk to the structures.