Increased demands to achieve
durable concrete structures with increasingly longer service life requires more
detailed investigations and knowledge of e.g. potential chloride ingress or
risk of cracking in the concrete due to heat generation during hardening and/or
shrinkage. In the last 10-20 years concrete mixes have moved towards more dense
concrete to obtain high resistance to chloride ingress. As the concrete becomes
more dense the concrete mechanical properties change and often the risk of
cracking increases, which consequently can reduce the durability of the
structure. In other words durable concrete can under improper use cause
non-durable structures. By means of computer simulations of the hydration
temperature and the temperature induced stresses it is possible to predict the
risk of cracking and to determine appropriate measures to reduce the risk of
cracking. It is possible during planning of massive concrete castings to
minimise the preventive measures required to reduce the risk of early age
cracking such as cooling. This paper will be based on three case stories from
the Great Belt and the Oresund Link projects in Denmark, which demonstrates
that the potential crack risk can be simulated quite accurately. Based on three
dimensional simulations the importance of the static boundary conditions are
discussed and it will be demonstrated that under certain circumstances it is
impossible to avoid early age cracking due to the effect of autogeneous
shrinkage.