A service life model for internal frost damage in concrete

The idea behind the service life model presented in this report was published in 1979. It has thereafter been described and developed in a number of reports and papers. The basis of the model is the observation that a well-defined critical, or maximum allowable, moisture content exists, above which the material is severely damaged by frost, and below which it is unharmed also when freezing is repeated at numerous occasions. This means that there is an analogy between design with regard to frost resistance and design with regard to structural safety. The critical moisture condition corresponds to the fracture load at structural design, whilst the real moisture condition corresponds to the actual load in structural design - the load effect. This also means that design with regard to frost resistance is to a high extent a moisture mechanics problem - one must be able to predict the future moisture variation in all parts of the structure. The analogy with structural design means that the same theory can be used for calculation of the probability of frost damage as for the risk of structural failure. The report focuses on the moisture mechanics part of the problem - i.e. the load part. The possibility to predict moisture by theoretical calculation is evaluated, and found to be small.