Define the following terms: a. Saturated surface-dry condition of aggregates b. Absorption of aggregates c. Free water on aggregates d. Referring to Figure 5.9, which portion of the water in the aggregate reacts with the cement in the PCC mix?

Aggregates are inert materials such as sand, gravel, crushed stone, and recycled concrete that are combined with cement paste to form concrete. They make up approximately 60-80% of the volume of concrete and play a critical role in its strength and durability. Aggregates provide bulk, stability, and resistance to wear, impact, and volume changes caused by moisture and temperature variations. They can be classified based on their size, shape, texture, and density and should be carefully selected, tested, and proportioned to achieve the desired properties and performance of the concrete.