Introduction of a full-range model for liquid and vapor transport properties of autoclaved aerated concrete

The hygric performance of autoclaved aerated concrete is a key determinant for many other material properties as e.g. thermal conduction, carbonation or shrinkage behavior. Laboratory determination of hygric material properties, i.e. moisture storage and moisture transport, is hence a prerequisite and a standard in production and process supervision. In this context, prediction and simulation of the hygric material performance based on numerical calculation models has become a widely used research and design tool. However, for assessment of the material behavior under variable climatic conditions, the hygric material properties have to be determined in a first step. In a second step, these properties have to be transformed into the non-linear coefficients required by these numerical calculation models. This paper is the second of two focusing on the second step. It introduces a full-range hygric material model bridging the gap between measured material properties and the non-linear storage and transport coefficients in the transfer equation. The model is based on the conductivity approach and relies on a bundle of tubes approach to derive the transport function from the pore structure of the material. By extending this approach with a mechanistic treatment of serial and parallel structured transport, a semi-empirical material model is developed providing a high flexibility and adjustability. The model is applied for an aerated autoclaved concrete. Input data are basic material properties obtained by the methods introduced in the first paper [26]. The approximation procedure is described and the achieved accuracy is discussed. In conclusion, the model is very suitable for sophisticated research as well as for a broad application to autoclaved aerated concrete in particular, and to porous materials in general.