CALCIUM LEACHING OF ROCK CONCRETE INTERFACE USING DEM

Rock Engineering 2009 - Rock Engineering in Difficult Conditions
Cedric Lambert, Olivier Buzzi, Anna Giacomini,
Abstract Leaching of concrete is a well known phenomenon which takes place as soon as concrete is exposed to water for a significant time. Wide knowledge has been acquired on the influence of leaching on the mechanical properties and porosity of bulk concrete and mortar. However, little data is available on the influence of leaching on the hydro mechanical behaviour of interfaces. The mechanical behaviour of leached concrete interface has been investigated using the particle flow code PFC3D. The distinct element method has been chosen because it allows one to simulate the evolution of the macro porosity during the leaching process by randomly deleting a fraction of the particles. Moreover, the progressive degradation of the interface asperities during shearing can also be captured. These two features are of major significance to reproduce the mechanical behaviour of leached interface. The results of the shear tests show a progressive loss of mechanical strength for the interface when the thickness of the leached zone increases. Logically, the failure criterion of the interface is also reduced. A qualitative change in behaviour is also observed: the interface initially displays a contractant/dilatant behaviour, which turns into a fully contractant response with leaching
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