Chloride ingress is a common cause of deterioration of reinforced
concrete structures. Concrete may be exposed to chloride by sea
water or deicing salts. The chloride initiates corrosion of the
reinforcement which through expansion disrupts the concrete.
Modelling the chloride ingress is an important basis for designing
the durability of concrete structures. As an example the Danish
Great Belt link is designed to have 100 years durability based on
calculation of chloride ingress.During the last 15 years the types
of concrete used in practice have changed substantially. Due to
plasticizers and mineral additives concretes with higher strengths
and reduced permeability are produced. Recently it has become
clear that traditional chloride ingress models do not apply to
modern concretes. Actually, the life time model used for the
Danish Great Belt link has shown up to be based on wrong
assumptions.Chloride ingress in modern concretes cannot be
followed with conventional measuring techniques. This makes it
difficult to develop and test new models. However, prefatory
experiments have shown that electron probe micro analysis, EPMA,
is applicable for this purpose. The geometric resolution for the
EPMA method is 100-1000 times better than for conventional
techniques.The present project is aimed to give a better
understanding of the physical-chemical nature of chloride ingress.
A number of different cement pastes and mortars are examined
ranging from traditional to modern high-performance types. The
pastes and mortars are exposed to synthetic seawater from 1 day to
half a year. Thereafter, the samples are examined by EPMA.
Modelling of the measured profiles focuses on a physico-chemical
understanding of the mechanisms.
|Number of pages||63|
|Publication status||Published - 1998|