The mechanical behaviour of different plain concrete specimens was evaluated a month after casting and several years later (20 and 26), under same testing conditions. Four concrete mixes were considered, with the same type and content of cement and aggregate,…
The mechanical behaviour of different plain concrete specimens was evaluated a month after casting and several years later (20 and 26), under same testing conditions. Four concrete mixes were considered, with the same type and content of cement and aggregate, but different aggregate gradings and water to cement ratios. All the specimens had the same curing since their casting. Compression tests employed cycles of axial deformation of increasing amplitude. The ratio between the energy required to reach collapse and the peak resistance was used as toughness index. Monotonic direct tensile tests were carried out on notched cylindrical specimens and the "characteristic length" was used as toughness parameter. The results show that the aged specimens have a considerably lower toughness, both in compression and in tension tests. Therefore when post-peak "ductility" and concrete toughness become important, e.g. for redistribution of local peak stresses, propagation of cracks massive concrete or resistance under extreme conditions, a design criteria referring to the expected long tenn concrete toughness should be used.