The paper presents results from three large scale experiments on seven reinforced concrete panels obtained during an extensive experiemental program. This was aimed at possible application of cement reduced (fly ash replaced)) concretee in the production of precast segmental linings for tunnels created by a tunnel boring machine (TBM). In particular, this paper is focused on the comparison of fire resistance of enhanced mixtures loaded by the Rijkswaterstaat (RWS) fire curve, which assumes 50 m3 fuel tanker fire lasting for 120 minutes. The presented results include spalling, overall damage of the surface and temperature distribution of the tested panels The paper also presents description of the proposed method for the evaluation of the extent of spalling during the experiments since, due to the extreme temperatures, the direct observation of the exposed surface is not possible. and Obsahuje seznam literatury
The paper reports on the determination of basic mechanical material parameters of several concrete and alkali activated concrete and fly ash mixtures intended for the construction of segmental lining used in TBM tunneling. The results of an extensive experimental program are discussed first. The principal attention is accorded to the experimental determination of specific fracture energy from a load-deflection curve, which, when compared to numerical simulations, shows certain inconsistency with the measurements of other material data. This is supported by teh derivation of the data from inverse analysis employing the elements of soft-computing. Dynamic simulation of crack propagation experiments is suggested to reconcile the essential differences and to identify the most important impacts affecting the results of experimental measurements. and Obsahuje seznam literatury