7.4 : 混凝土中的总空隙率

Consider a mass of concrete in which the total volume of voids includes the volume occupied by gel water, capillary pores, and entrapped air, each contributing to the overall porosity of the concrete structure.

The gel, which is the product of cement hydration, is made up of solid substances and water that is either physically retained or adsorbed onto the extensive surface area of the hydrates. The volume of this particular water is the volume of gel water.

It is estimated that one cubic inch of unhydrated cement would need approximately two cubic inches of space for its hydration products upon complete hydration.

Capillary pores are the spaces within the hydrated cement paste that are not occupied by the hydration products, and these pores can either be empty or filled with water.

During the process of mixing concrete, some air often gets trapped within the cement paste.

These entrapped air voids can reach up to 120 mils, which are substantially larger than the capillary voids and can negatively impact the concrete's strength.