A thermo-hygro-chemo-mechanical numerical approach to prevent problems of repair of concrete structures

In the field of civil engineering strengthening and repair of concrete structures are becoming more studied. Experience has shown that concrete structures repairs are often subject to premature cracking because the substrate prevents the free contraction of the new material of restoration. Indeed, as it is known, cement paste at early ages is subject to various physical and chemical phenomena which determine thermal, hygrometric, chemical and viscous strains. In order to quantify with a mechanistic approach these deformations, a THCM multi-phase model of hygrothermal and hydration phenomena in concrete at early ages has been developed by B.A.Schrefler, F.Pesavento and D.Gawin. The introduction of this numerical model in the French finite elements code Cast3M allows its opening to a wide range of applications including the study of repair problems, realized either with ordinary concrete, or with shrinkage-compensated or fiber-reinforced concretes. The paper will explain the multi-physics formulation of the numerical model and will introduce some application examples.