Assessment of alkali–silica reaction damage through quantification of concrete nonlinearity

Abstract

A newly developed nondestructive evaluation technique, Nonlinear Impact Resonance Acoustic Spectroscopy (NIRAS), is applied to concrete specimens in an ongoing assessment of aggregate alkali reactivity during standard concrete prism testing. NIRAS measures the nonlinearity in a specimen caused by the inception and growth of microcracks throughout the sample and debonding at the aggregate/cement interface. NIRAS is used to exploit the nonlinear effect of excitation amplitude dependent resonance frequency changes, which are related to nonlinearity measurements of concrete samples cast with aggregates of varying reactivity. To relate microstructural changes to changes in nonlinearity and expansion, sample characterization is performed with uranyl-acetate staining. The results demonstrate the utility of NIRAS for not only assessing the potential for ASR under standardized test conditions, but for more general damage characterization in concrete and assessment of “job mixtures.” NIRAS can distinguish reactive from nonreactive aggregates without ambiguity, as supported by sample characterization results.