Title: Quantifying Microscopical Examination of Concrete for AAR and other Durability Aspects

Author(s): Ian Sims, Barry Hunt, and Bruno Miglio

Publication: Symposium Paper

Volume: 131

Issue:

Appears on pages(s): 267-288

Keywords: alkali-aggregate reactions; concretes; deterioration; durability; microscopy; sampling; tests; Materials Research

DOI: 10.14359/1213

Date: 3/1/1992

Abstract:
Microscopical examination of hardened concrete is the only method for definitively identifying the presence of AAR and also providing valuable information regarding many additional criteria that are relevant to the durability of concrete. It is common, however, for the extent of such evidence to be indicated by the use of subjective terms only, which inhibits the comparison of different examples and does not allow correlations to be made between microscopical observations and any other data that indicate the quantity or severity of any damage to the concrete. A procedure is described for recording and quantifying the various microscopic features identifiable in thin section under a petrological microscope. It is shown by reference to example data that the procedure facilitates the objective comparison of different concretes and can also help to establish the relative extent and degree of deterioration that has occurred. The technique has been developed to improve the sensitivity of microscopy in the diagnosis of AAR but could be applied similarly to a range of threats to concrete durability.