The common design approach is faulty because we consider only the loading aspect, whereas the environmental aspect is equally important. This is because we have seen structures failing only due to environmental impacts on the structure, and not because of overloading.
There are number of models available online free of charge which gives an idea of various factors.
Life 365
Life 365 software helps predict how the structure fails. It divides the corrosion aspect into two time periods: the initiation period (ti) and the propagation period (tp). The following inputs are required to predict the initiation period:
- geographical location
- type of structure
- nature of exposure
- depth of clear cover
- protection strategy scenarios
- water-cement ratio
- type and quantity of supplementary cementitious materials
- corrosion inhibitors
- type of steel
- coatings
- type and properties of membranes and sealers.
The DuraCrete approach overcomes the shortcomings of Life 365 and provides a greater calculation accuracy towards prediction of structures which can get affected by chlorides. In this method, the following durability limit states have been identified regarding service life:
- depassivation of reinforcement
- cracking of concrete cover
- spalling of concrete cover
- collapse of the structure.
