The second period encompasses the time in which
the stress builds-up, Tstress, as corrosion products, having
filled the porous zone, exert an expansive pressure on the
surrounding concrete. The model assumes that this pressure increases linearly as the volume of corrosion products
increases until the internal tensile stresses exceed the tensile strength of concrete at which time cracking of concrete
cover occurs. It should be noted that this assumption is
valid up to the point of cracking, after which time pressure
distribution is not uniform. Cover cracking marks the end
of functional service life of a corroded structure where
structural rehabilitation is needed.