ABSTRACT
Ulm and Coussy (1998) have proposed a thermodynamically based model for concrete in which the driving forces cementing the granular matrix are taken into account. This framework fulfils the model by
Tamagnini (2000;2004) and the entropy inequality reads:
in which the free energy is defined as:
and the terms in equation (1) are:
Am represents the driving force controlling the rate of Sr (water degree of saturation) and has the meaning of a Gibbs potential. It is the difference between the capillary stress (or energy) as defined by Hassanizadeh and Gray (1990) and Coussy (2004) and the suction (intended as the difference between the air and water pressure). χ and ζ are respectively: the hardening kinematic variable (volumetric plastic strains) and the hardening force controlling the frozen energy of the granular matrix; σ ′ is the Bishop’s stress and εis the strain tensor.
