This document provides an overview of prestressed concrete design. It defines concrete as a mixture of aggregate and cement held together by a hardened paste. Concrete is classified based on unit weight and strength, and includes types such as lightweight, normal-weight, and high-strength concrete. The document describes the three states of concrete as plastic, setting, and hardening. It outlines several material properties of concrete including workability, uniformity, strength, durability, and watertightness. It also discusses admixtures that can be added to concrete to modify its properties.