Exp-Ref: a simple, realistic and robust method to assess service life of reinforced concrete structures

The hereby proposed 'Exp-Ref' method of Service Life Assessment presents two characteristic features. First, it is 'Experimental', because the prediction is based on the 'in situ' ND determination of the cover depth d and of the coefficient of air-permeability kT. Second, the assessment is not based on a prediction starting from t=0 as most other methods, but from a 'Reference' condition corresponding to 50 years. This is the service life expected if the prescriptions of concrete quality (EN206-1 and EN 13670) and cover depth (Eurocode 2) are observed. By comparing the actual values of d and kT measured on site with those corresponding to the reference condition, it is possible to estimate the service life (SL) with a simple formula. The proposed method is simple and realistic (is based on real data obtained on the end-product, referred to values for 50 years of SL) and is robust (neither ambiguities nor subjectivity by selective choice of model parameters as for other methods). It provides also a probabilistic representation of SL as a single value is assigned to each measurement point. A couple of application cases are presented.