In this section of the book Ching is talking about Concrete, Masonry, Steel, Stoon and Wood. Concere is a mixed of water,aggregate and cement. There is 5 different types of cements are listed in Ching’s book. Adding Aggregate to Concrete is important to the strength, weight, and fire resistance of the hardened concrete. Masonry refers to a building with different natural products such as Bricks, Stone and Concrete blocks. Steel is basically any type of iron that have a carbon content less then cast iron and more than wrought iron. It has differen types of shaping such as first Structural tubing which can be either square, rectangular or circular. Second WT shape or L shape. Third is Basrd that can be either square, round and or even flat. Stone is an aggregate or combination of minerals which is composed of inorganic chemical substances to qualify as a construction material. to be qualified stone should have: strenght, hardness, Durability, workability, density and appearance. Reffering to ching’s book Wood is strong, durable, light in weight and easy to work with as a construction material. Two of the major classes of wood are softwood and hardwood.