Atypical brittle failure and compression characteristics of polymer based on acoustic emission

Abstract

Foamed polymer is frequently used for waterproofing repairs in underground engineering. Since the polymer acts as a plug in structure fractures, the mechanical characteristics of its foaming are essential. Its compressive damage constitutive equation is closely related to the engineering structure life. This study divides polymers into two types based on whether or not the molded skin is removed. Based on acoustic emission monitoring, quasi-static cyclic loading compression tests were conducted under a specific engineering background. Then, the failure modes were classified, and an energy-based constitutive analysis of two damage factors was conducted. The test results show that the presence of molded skin led to “atypical-brittle” failure characteristics, maintaining stepwise stress drop after yielding without densification. Acoustic emission energy-based damage factors can be incorporated into the constitutive model to reflect the damage process in advance. Furthermore, the conventional damage factor-based constitutive model was modified by a compaction factor to describe the characteristics from the elastic state to the atypical-brittle failure. From the perspective of the failure behavior of polymer materials, this work sheds light on grouting materials’ design.