Expansive spalling mechanism of concrete due to high temperature based on developed hygro-thermal-mechanical model by 3D-RBSM-TNM

• Published in: Engineering fracture mechanics 2023-05, Vol.284, p.109216, Article 109216
• Main Authors: Miura, Taito, Nakamura, Hikaru, Yamamoto, Yoshihito
• Format: Article
• Language: English
• Subjects: Explosive spalling; Hygro-thermal-mechanical model; RBSM-TNM; Thermal stress; Vapor pressure
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2023.109216

•The coupled analysis based on Hygro-Thermal-Mechanical Model was developed.•Thermal stress, vapor pressure transfer through crack and mechanical properties change due to high temperature were applied to proposed model.•The influence of thermal stress, vapor pressure transfer through crack and mechanical properties change due to high temperature were validated.•Thermal stress influences the cracks generation at inner area of concrete and vapor pressure behaves a trigger of explosive spalling. Explosive spalling of concrete has been explained based on thermal stress and vapor pressure, and the mechanism of explosive spalling has been still discussed. In this study, the influence of several factors on the mechanism of explosive spalling due to high temperature was validated using the coupled analytical system: Rigid Body Spring Model-Truss Network Model (RBSM-TNM) based on hygro-thermal mechanical model. Truss Network Model can evaluate the heat transfer and vapor pressure transfer. The thermal stress and vapor pressure are applied to 3D-RBSM as an initial strain and initial stress, respectively. This proposed analysis can describe the complicated explosive spalling phenomena. Moreover, the accumulation of vapor pressure in the cracks and the change in mechanical property due to high temperature can be taken into account. In this paper, the influences of thermal stress, vapor pressure, vapor pressure transfer through cracks, and the change in mechanical property due to high temperature on the explosive spalling are precisely elucidated. As a result, it was confirmed that thermal stress causes the distributed cracks at the internal area while it does not involve the explosive spalling and a trigger of explosive spalling is the vapor pressure.