Special trade contractors primarily engaged in concrete work, including portland cement and asphalt. This industry includes the construction of private driveways and walks of all materials. Concrete work incidental to the construction of foundations and concrete work included in an excavation contract are classified in SIC 1794: Excavation Work; and those engaged in construction or paving of streets, highways, and public sidewalks are classified in SIC 1611: Highway and Street Construction, Except Elevated Highways.
Drywall, Plastering, Acoustical and Insulation Contractors
Concrete—a mixture of portland cement, sand, gravel, and water—is used for the construction of everything from patios and floors to dams and highways. Special trade contractors involved in concrete work provide the following products and services: private asphalt parking areas; blacktop work; concrete work for private driveways, sidewalks, and parking lots; culvert construction; curb construction; pouring concrete to build foundations; grouting work; parking lot construction; patio construction; sidewalk construction, except public; and stucco construction.
The most recent U.S. Census Bureau reports indicated that more than 30,000 establishments are involved in concrete contracting. These companies employed 190,000 cement masons, concrete finishers, and terrazzo workers in 2002, according the U.S. Bureau of Labor Statistics. Portland cement consumption declined in the Northeastern and Mountain states in 2001, due in large part to the economic recession—exacerbated by the September 11 terrorist attacks— which prompted a slowdown in commercial and industrial construction and transportation expenditures. Compared to a 5 percent growth rate in 1999, portland cement consumption grew by only 0.2 percent in 2001. However, consumption was expected to grow 1.4 percent in 2002 as every region of the United States saw gains.
The construction industry can be divided into three segments: general building contractors, heavy construction contractors, and special trade contractors, which includes those engaged in concrete work. General building contractors build residential, industrial, commercial, and other buildings, while heavy construction contractors build structures such as roads, highways, and bridges. Special trade contractors usually focus on one trade and work under the direction of general contractors, architects, or property owners. Beyond completing their work to specification, special trade contractors have no responsibility for building the structure in its entirety.
Concrete can be classified by the type of aggregate or cement used, by specific characteristics, or by production methods. Ordinary structural concrete is characterized by its water-to-cement ratio. The lower the water content, all else being equal, the stronger the concrete...