NUMERICAL SIMULATION OF MOISTURE DIFFUSION IN A CONCRETE PATCH REPAIR

摘要

Durability of a patch repair has become a major concern in the recent times because of cracking and failures of repair layers over a short span of time. A phenomenological model which is capable of modeling a chain of critical processes that is set off in a patch repair system and which results in the generation and dissipation of stresses in the system has been developed. Moisture diffusion, a primary critical process in a repair system is addressed in this paper. A non-linear 2-D finite element program DIANA-2D (Diffusion ANAlysis) has been developed for repair systems. A phenomenological approach in which various transport mechanisms at microlevel are lumped together by defining "diffusivity" of the material at macroscopic level is adopted. A miniature patch repair system consisting of a thin layer of repair material placed over a hardened concrete substrate is analyzed. The spatial and temporal moisture content is obtained and the moisture loss history over the specified time intervals is computed.