Evaluation of a direct shear test setup to quantify AAR-induced expansion and damage in concrete

Abstract

Alkali-Aggregate Reaction (AAR) is one of the most harmful distress mechanisms affecting the durability and serviceability of concrete infrastructure worldwide. Over the years, a number of comprehensive testing protocols have been developed to appraise the amount of damage, expansion attained to date and mechanical properties reductions of concrete affected by AAR. Promising results were found through the use of advanced mechanical and microscopic techniques such as the Stiffness Damage Test (SDT) and Damage Rating Index (DRI). However, there is still a need to develop new “simple” yet “reliable” test procedures able to quantify AAR expansion and damage. This paper presents the use of a modified shear strength setup to appraise AAR development. Concrete samples incorporating a wide range of reactive aggregates were fabricated, monitored and tested under the proposed shear setup at distinct damage degrees. Results show that AAR influences significantly the shear strength of affected concrete and thus the proposed test setup seems promising in assessing AAR expansion and damage. Yet, further data is still needed to confirm the reliability of the results gathered in this research.