Structure and Physical Properties of Hardened Portland Cement Paste

Methods of studying the submicroscopic structure of Portland cement paste are described, and deductions about structure are presented. The main component, cement gel, is deposited in water‐filled space within the visible boundaries of a body of paste. Space filled with gel contains gel pores; space not filled by gel or other solid material is capillary space. Hygroscopicity of cement gel, and capillary pores, accounts for various aspects of the properties and behavior of concrete. Data on gel and paste structure are used in discussing strength, permeability, volume stability, and action of frost.