For 50 years power floats and trowels have been used for finishing large areas of concrete flatwork. In order to achieve the highest production rates and greatest profits, the machine must be used efficiently. Efficiency comes only with knowing the machine and its proper uses.
The size of a machine is expressed by the diameter, in inches, of a circular area outlined by the moving blades. Machines vary from a 20-inch hand held model to an 96-inch riding model. The blades of the machine finish the concrete as they are swirled around the surface. Blades are classified as float (10 inches wide), trowel (6 inches wide) or combination according to their basic use. Engines for troweling and floating machines are usually gasoline-powered and range in size from 3- to 11-horsepower.
GENERAL PRINCIPLES OF FLOATING AND TROWELING
Floating embeds coarse aggregate, removes humps and valleys and compacts the concrete surface. The concrete surface must be sufficiently hard and free of bleed water before power floating begins. Troweling is done after floating to produce a dense, smooth, hard surface. For both floating and troweling operations the angle of the blade is important. For floating, the blade must be absolutely flat to prevent tearing or gouging of the surface. On each successive troweling pass the angle of the trowel blade is slightly increased to exert greater pressure on the concrete surface.
Before floating and troweling begin, it is generally desirable to plan the operations to ensure complete and efficient finishing. Power floating is started in the direction perpendicular to the direction of bullfloating. If a second floating pass is made it should be at a right angle to the first pass. Also, successive troweling operations are perpendicular to initial troweling. Each successive finishing pass should overlap the previous pass by half the width of the machine. This type of finishing pattern will ensure complete slab coverage and minimize surface imperfections.