Introduction

Pore structure is a very important microstructural characteristic in a porous solid because it influences the physical and mechanical properties, and controls the durability of the material. The physical and mechanical behaviors of a porous material are strongly affected by the way in which the pores of various sizes are distributed within the solid. Materials with the same total pore volume can exhibit entirely different characteristics, depending on whether the material contains a small number of large pores or a great number of small pores. A lot of research has been carried out in the past in order to understand the principles and reactions involved in the formation of the pore structure of a composite material, and to provide models that describe it. The accuracy of a model developed to predict the pore structure in a porous solid can be determined from how well the experimental data fit the outcome predicted by the model. Characterization of the pore structure is complicated by the existence of pores having different shapes and sizes and by the connectivity between pores.