Hygric Permeance - New Calculation Methodology

Abstract:

After intensifying the knowledge of hygric permeance (HP) in multi-layered test samples, which were subjected to the imbibition process, a significant set of HP values (with different interface types) was experimentally achieved. This was done in order to develop a new model which allows estimating more correctly the hygric permeance. The idea is predicts the HP with several scenarios, i.e., different interfaces (perfect contact, hydraulic contact and air space interface), interfaces heights and materials studied, in the attempt to estimate the HP without the need to resort to the measurement by the experimental route in the attempt to estimate the HP without the need to resort to the measurement by the experimental route and even with possible measurement, generator automatic calculation (without human opinion/criteria). In this paper, the Hygric Permeance will be calculated by two different methods, gravimetric and gamma ray methods, and a new methodology proposes. The maximum flows transmitted were determined by the slope of the mass variation per contact area in function of the time involved. When having interface, the calculations admit that the first layer is saturated and that all the increased weight stems becomes from the relative humidity that penetrates the interface. The new methodology proposed is analysis of the prevision mathematical model that describes the mass variation per contact area in function of the time, after the “knee point”. This work it is the first attempt to provide a set of values that refer from hygric permeance in masonry of building walls, these being random values experimentally determined.

• Periodical: Diffusion Foundations (Volume 24)
• Pages: 145-162
• DOI: https://doi.org/10.4028/www.scientific.net/DF.24.145
• Online since: September 2019
• Authors: A.C. Azevedo*, João M.P.Q. Delgado, A.S. Guimarães, I.M. Ribeiro
• Keywords: Hygric Permeance, Interface, Knee Point, Moisture Transfer, Numerical Simulation, Water Absorption

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