engleski

Fire performance of concrete composite segments used as secondary tunnel linings

Considering the fact that one of the main problem with occurrence of fire in tunnels is damage to the conventional secondary tunnel lining, research work within Eureka project E!2823 was mainly concentrated on the development of new system for prefabricated secondary tunnel lining, as fire resistant one. This system is based on a construction of precast segments consisting of four layers: first double layer, that is to be fire-resistant, second layer as structural concrete and last layer that is to be water resistant. Different combinations of composite materials used in these precast segments were tested on fire loads in accordance with TNO test (Rijkswaterstaat curve), which results are presented in this paper. The best performance had shown micro-concrete (lightweight micro-concrete), whose mechanical and physical properties were researched after being exposed to high temperatures, such as are developed during tunnel fire. Testing of mechanical and physical properties was carried out before and after fire testing, as well as the analysis of compressive strength dependence on temperature load. Special attention is dedicated to results of pore-size distribution in the fresh and in the hardened structural concrete, used in the control sample, and in the micro-concrete, used in optimal combination of composite segment.

concrete porosity; fire testing; precast secondary tunnel lining; residual concrete strength

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