Linear propagation models of deterioration processes of concrete

SUMMARYThe most known model is that published by Tuutti with two phases in time: corrosion initiation and propagation. In this model the corrosion initiation phase has been frequently considered, but the corrosion propagation phase has been seldom addressed. In the present work the propagation phase is generalised to not being only with a constant corrosion rate, but also with the alternatives of presenting non-constant corrosion rates through a sequence of consecutive periods of constant corrosion rate (bi-linear behaviour). The other most frequent attacks are alkali-silica reaction or sulphate attack, acid or leaching by pure waters and frost attack. In the present paper it is proposed as an inference from the corrosion model that they can be modelled through the same linear pattern of an initiation and a propagation period. Their rates of deterioration can be constant or the rates can be changing as a sequence of shorter linear periods.