Cement paste ordinarily constitutes about 25% to 40% of the total volume of concrete.

In properly made concrete, each particle of aggregate is completely coated with paste and all of the spaces between aggregate particles are completely filled with paste, as illustrated in Fig. 1-2.

Following are some advantages of reducing water content;

Increased compressive and flexural strength

Lower permeability, thus increased water tightness and lower absorption

Increased resistant to weathering

Better bond between successive layers and between concrete and reinforcement

Admixtures are commonly used to 1) adjust setting time or hardening, (2) reduce water demand, (3) increase workability, (4) intentionally entrain air, and (5) adjust other concrete properties.

Slump is used as a measure of the consistency of concrete. A low-slump concrete has a stiff consistency.