Identification of Logarithmic-Type Creep of Calcium-Silicate-Hydrates by Means of Nanoindentation

In order to relate the complex macroscopic behaviour of concrete with finer-scale properties of cement paste, aggregates, porous space, etc. multiscale models are developed. Here, in addition to homogenisation schemes establishing the relation between the properties of the constituents, e.g. matrix and inclusions, and the properties of the composite material, experimental methods for identification of finer-scale properties are required. Recently, the elastic properties of the main clinker phases in ordinary Portland cement (OPC) and calcium-silicate-hydrates (CSH) were identified by nanoindentation (NI). In this paper, the NI technique is extended towards identification of the viscous, time-dependent behaviour of CSH, i.e. the main finer-scale binding phase in OPC-based material systems. Hereby, a logarithmic-type creep behaviour is identified, corresponding perfectly to the creep behaviour encountered for mortars and concrete.