Development of Transient Permeability Theory and Apparatus for Measurements of Cementitious Materials

摘要

A permeability apparatus was designed and constructed that would allow a rapid and accurate measurement of water transport in concrete. The principle of the apparatus was to subject a test specimen to a small pressure differential and to monitor both the pressure decay and the pressure rise resulting in response to the pressure pulse. The apparatus consists of a design which can isolate two pressurized, large volume reservoirs on both sides of the test specimen where the test specimen was acting as a permeable membrane between the two. Very rapid measurements are possible with this apparatus for specimens possessing permeabilities on the order of microdarcy to nanodarcy. However, in order to measure permeabilities below a nanodarcy the problems of establishing pressure equilibration throughout the test specimen becomes increasingly more difficult. To explain the behavior of cementitious materials subjected to pressure, mathematical relationships were developed building upon the work in existing literature on fluid flow in porous media subjected to a transient pressure pulse. (Copyright (c) 1993 National Academy of Sciences.)