Effective ageing linear viscoelastic properties of composites with phase precipitations: comparison between numerical and analytical homogenization approaches

T. Honorio (1) , B. Bary (1) , J. Sanahuja (2)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 EDF R&D - EDF R&D

Dissolution and precipitation processes are present in key phenomena affecting the behaviour of cement-based materials. At early-age, due to hydration process, new phases are formed within capillary pores; at late ages, the material can be submitted to degradation processes in which hydrated phases dissolve. These processes reflect in an ageing behaviour of the material. Cementbased materials exhibit viscoelastic behaviour. Recently, analytical homogenization tools have been developed to upscale the effective properties of composites in an ageing linear viscoelastic framework [1,2]. Taking advantage of these tools, an extension of Bazant's original solidification theory [3] was proposed in a 3D tensorial context [4].In this paper, we propose to benchmark these analytical approaches by comparing with numerical homogenization to estimate the behaviour of ageing composites in different scenarios. To this end, 3D numerical samples are generated by randomly distributing inclusions of various sizes and shapes in a box [5,6]. The standard finite element method is then applied to solve the problem involving different phase behaviours and external loadings. Here, classical creep and relaxation loadings are considered. The effects of the phases contrast on the response obtained by both numerical and analytical approaches are discussed. Also, whilst analytical homogenization is often limited to spheroidal forms, numerical homogenization can deal with more complex geometries. We compare the response of solidification in two main morphologies spherical and convex polyhedral inclusions. In the latter case, samples with flattened and elongated polyhedral aggregates of different aspect ratios are generated so as to investigate the influence of their shape.The results provided here go towards a better description of the dissolution precipitation processes, which is an important feature in the description of cement-based materials ageing behaviour.

Keywords: Linear Viscoelasticity; Ageing; 3D Simulations; Heterogeneous materials; Homogenization

Domains: Nuclear Experiment [nucl-ex]; Nuclear Theory [nucl-th]

T. Honorio, B. Bary, J. Sanahuja. Effective ageing linear viscoelastic properties of composites with phase precipitations: comparison between numerical and analytical homogenization approaches. Framcos9 - 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures, May 2016, Berkeley, United States. ⟨cea-02509793⟩