دانلود رایگان مقاله تاثیر هیسترزیس جذب در ضرایب انتشار نمایش با پتانسیل های مختلف رطوبت

Abstract

This paper continues the discussion in a previous paper [Saeidpour and Wadsö doi:10.1016/j.cemconres.2016.02.003] where a clear effect of sorption hysteresis was seen in moisture diffusion coefficients for cement-based materials. Coefficients with vapor content as potential (Dv) had different values depending on whether the sample was in absorption or in desorption. In this paper we recalculate these Dv coefficients into coefficients with other potentials and draw them as a function of different potentials. The aim is to see if the effect of hysteresis disappears with an optimal choice of representation. The best choice was to draw Dv is as a function of the degree of saturation (concentration, moisture content).

4.4. General discussion

Looking at the results in Figs. 1-3, it is seen that Fig. 2b shows the smallest difference between absorption and desorption, closely followed by 2a. This indicates that when the diffusion coefficient with vapor content as potential (Dv) is used as a function of the degree of saturation (or moisture content or concentration) the effect of absorption/ desorption does not need to be taken in to account. However, this study was rather limited and this tentative conclusion should be further tested. It may seem odd that a transport coefficient using one potential (vapor content) should be used together with another potential (degree of saturation, concentration) describing the state of the water. However, it may be natural that two potentials are used together to reduce the effect of hysteresis, one to describe the conductivity and one to describe how the conductivity changes with a change in moisture content/ state. Below we give some arguments for that the best choice of potentials that we have indicated above is the best representation also in terms of the physics of the processes. However, these arguments are rather weak and should only be seen as the start of a discussion about this.