PERMEABILITY AND SORPTION PROPERTIES OF MATURE NEAR-SURFACE CONCRETE

Measurements of the permeation or sorption characteristics of concrete are increasingly being used as indexes of durability or resistance to chemical attack of new concrete. This investigation was intended to f ind if these relatively simple, inexpensive tests can be used to asses s the condition of the concrete in mature structures that may have det eriorated during their service life. Such structures may be nearing th e end of their design life, but it may be necessary to extend their se rvice life. In such cases the state of the concrete needs to be assess ed. The paper explores the profiles of oxygen permeability and water s orption, with distance from the surface, of concrete taken from in-ser vice structures typically in the 20 to 30 year age range and hence pro poses generalized permeability and sorption profiles. However, as the two types of measurement, permeability and sorption, do not, for concr ete from in-service structures, correlate one with the other or with c arbonation depth or strength, it is unlikely that either parameter is a valid index of the overall state of concrete from a mature structure .