A new method of applying long-term multiaxial stresses in concrete specimens undergoing ASR, and their triaxial expansions

Abstract

An understanding of the response of multiaxially loaded concrete to the expansive reactions, such as alkali-silica reaction (ASR), remains a prerequisite to predict the long-term behavior of ASR-affected concrete structures, such as dams and containment structures. However, no suitable techniques exist to apply biaxial and triaxial stresses in concrete specimens, and to sustain the stresses for monitoring the long-term behavior of concrete. Consequently, state-of-the-art numerical modeling of concrete structures undergoing ASR relies on the experimental findings obtained from specimens with insufficient restraints. This paper presents the development of a new method to apply multiaxial (uniaxial, biaxial and triaxial) stresses. The stresses were applied to multiple concrete cube specimens, and were sustained for 1 year as ASR evolved in the specimens subjected to an accelerated condition of 50 °C temperature and close to 100 % relative humidity. The specimens were measured for longitudinal expansion in the three directions. The merit of the proposed method in the study of ASR is illustrated by presenting the results on the triaxial expansions of several unloaded and multiaxially loaded cube specimens until the exhaustion of the reaction. The results demonstrate a strong influence of multiaxial stress states on the ASR expansion of concrete.