Evaluation of residual elasticity of an internal expansion-induced concrete

This paper addresses the degradation due to neutron radiation exposures of concrete consisting in various rock-forming silicate-based aggregates and cement paste. We are interested in the evaluation of the residual elastic properties of concretes subjected to a high fluence of fast neutron irradiation by means of an extended composite sphere model. We first introduce briefly the main features of the model, and then show how the damage resulting from the aggregate expansion generated by their physical and structural changes upon irradiation can be captured and accounted for. To validate the established analytical solutions of the model and illustrate its predicting performance, we apply it on two specific concretes: (1) a concrete consisting of an ordinary cement paste and silicate-based aggregates of various sizes; and (2) a concrete consisting of massive serpentine aggregates and a pure aluminous cement paste. In both cases, the model predictions are compared with the available experimental measurements, and a good accordance between them is found. The composite sphere model gives a full description of the damage development in the mortar and identifies the primary role of the aggregate expansion on the material degradation mechanisms. In this first attempt, only damage in the mortar is accounted for in the modelling while the aggregates are assumed to behave elastically.