Experiment on ASR Expansion Under Both Active and Passive Restraints by Post-Tensioned Prestressing

Understanding the expansion of Alkali-Silica Reaction (ASR) under restraint and its impact on the mechanical properties of concrete is crucial for evaluating and predicting the performances of concrete structures damaged by ASR. Nowadays, ASR damage has even been observed in prestressed concrete structures, which are considered highly durable. Evaluating their performance, particularly in terms of structural safety, necessitates consideration of both active and passive restraint influences. This study aims to investigate the effects of prestress on the expansive behavior of concrete due to ASR and to discuss this behavior under both active and passive restraint conditions. The focus of this research is post-tensioned prestressed concrete at low-stress levels. Experimental results indicate that concrete expansion along the restraint direction is dependent on the restraint rate, expressed by both prestress and steel bar. Moreover, expansion perpendicular to the prestress direction is greater than stress-free expansion. These findings result in nearly identical volumetric expansion in different restraint conditions. Furthermore, the study delves into the degradation of the modulus of elasticity under restraint and considerations in the assessment of real structures.