Interfacial strength study between a concrete substrate and an innovative sprayed coating

•Light mortar based on a silica aerogel solution for thermal rehabilitation.•Mechanical characterisation at the interface with its substrate.•Influence of stress concentration on experimental results.

This paper investigates the mechanical behaviour, at a local scale, of a solution of a thick thermal insulation pneumatically placed from the outside for refurbishment. In particular, this study shows the strength of the critical area: the interface with its concrete substrate. It is possible to define the failure criterion of this interface using the slant-shear test. However, due to a difference in rigidity between the concrete substrate and the insulating coating, a numerical study is necessary to better understand the experimental results and to assess the possible stress concentrations at this interface, which could distort the experimental results.