concrete degradation

"To build environmentally sustainable concrete structures, it is clear that instead of strength, the 21st century concrete practice must be driven by considerations of durability."

from P.K. Mehta and R.W. Burrows: "Building Durable Structures in the 21st Century",
Concrete International, March 2001, pp.57-63.

Of all engineering materials concrete is the most widely used one, on a tonnage basis.
The main mechanism of degradation of steel-reinforced concrete is corrosion damage to the reinforcing steel (rebar).

rebar2.jpg (114316 bytes) rebar6.jpg (115377 bytes)

Contrary to common belief, concrete is a complex composite material, whose structure and properties can change over time.
It is generally recognized that the environmental degradation of the concrete infrastructure is a serious, large scale and costly problem in many parts of the world .