Although concrete block is made in many sizes and shapes (figure 8-4) and in both modular and nonmodular dimensions, its most common unit size is 7 5/8 by 7 5/8 by 15 5/8 inches. This size is known as 8-by-8-by-16-inch block nominal size. All concrete block must meet certain specifications covering size, type, weight, moisture content, compressive strength, and other characteristics. Properly designed and constructed, concrete masonry walls satisfy many building requirements, including fire prevention, safety, durability, economy, appearance, utility, comfort, and acoustics.

Concrete blocks are used in all types of masonry construction. The following are just a few of many examples:

Exterior load-bearing walls (both below and above grade);

Interior load-bearing walls;

Figure 8-4.-Typical unit sizes and shapes of concrete masonry units.