Predictive Testing for Heat Induced Spalling of Concrete Tunnels—The Influence of Mechanical Loading

Abstract

This paper describes Phase II of a project being undertaken to develop a predictive test method to investigate heat-induced explosive spalling of concrete, with a specific focus on concrete used in tunneling applications (but obviously applicable to other applications). The test method seeks to allow careful control of the thermal and mechanical transient conditions influencing the occurrence of heat-induced concrete spalling, thus enabling convenient, representative, repeatable, and comparable testing to be carried out on various concrete mixes under various potentially relevant conditions. Phase I of the project focused on establishing suitable thermal exposures to use for testing based on the thermal exposures which a sample would be exposed to during a standard furnace test (cellulosic or modified hydrocarbon) in the Promethee testing facility at CERIB in France. The work described in this paper deals with establishing suitable mechanical loading conditions for a spalling test, the focus in the current work is to enable provision of a representative test for precast segmental concrete tunnel linings (as opposed to sprayed or cut-and-cover tunnel linings). With small adaptations the spalling test method could be adjusted to suit other applications. This paper focuses on the motivation for developing the testing method and outlines the testing to be carried out. Tests are currently underway, and the full suite of results will be presented at the conference.