Procedures for finishing slabs-on-ground. Chapter 7. Chapter Topics. Striking off (screeding) the concrete Bull floating or darbying Highway-type straightedge Waiting period Edging and jointing Brooming Floating Troweling. Chapter Topics.
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Use power float and trowels in controlled patterns.
Start the first float pass perpendicular to the direction of last finishing procedure. Typically that last procedure is bull floating, so the first float pass is perpendicular to that.
Subsequent float passes are perpendicular to previous float passes. Each pass in the alternating direction refines the flatness of the floor until the concrete stiffens to a point where it can no longer be moved.
Floating or troweling in only one direction creates a wave, and repeated floating or troweling in only one direction accentuates the wave.
These waves lower the floor flatness and levelness and are difficult to remove during restraightening if that procedure is used.
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.
When a trowel blade is tilted or pitched at too great an angle, an objectionable “washboard” or “chatter” surface will result. If this occurs, reduce the tilt and continue troweling until the surface is smooth and level, after which the tilt may again be slightly increased.
The tilt is excessive if the leading edge of the blade is more than 1 in. above the concrete surface.