PROBLEM: Deterioration of reinforced concrete
Good quality reinforced concrete (or cement) usually begins deteriorating after 10/15 years. The following essential parameters effect durability: minimum value of characteristic resistance Rck; minimum water/cement ratio; minimum cement content; minimum thickness of concrete cover. Deterioration of reinforced concrete can be seen in various different ways: cracks in the concrete; spalling of cover; disintegration of the concrete; corrosion of the reinforcement rods.
The causes of the deterioration can be summarised into two categories:
- Bad design or poor quality materials
- Incorrect laying (forming of gravel clumps)
- Inappropriate curing processes
- Mechanical causes (lesions caused by stresses; micro cracks caused by dilation/shrinking; forming of ice in the matrix and aggregates)
- Chemical-physical causes due to environmental factors (deteriorating mechanisms of a chemical nature caused by water, air and land: permeability, diffusivity, capillarity, wash-out)