The process of installation of a new concrete skin is divided into several stages like reinforcing, filling, vibrating, smoothing with rod and, at last, the finish stage of skin installation is its trowelling with appropriate trowelling machine. Such machines are also named as helicopters.

Trowelling of concrete with helicopter is destined for smoothing the upper layer of concrete because after pouring the new skin the traces of rod as well as small holes (sinks) and filler (crushed stones) appear on its surface.

There are two main types of trowelling machines: single-rotor and double-rotor machines. The main difference of this equipment is the operator’s position at the working process.

The single-rotor trowelling machines are driven by the operator standing on legs and driving the helicopter using the long handle (hacker) existing in the content of a trowelling machine.  

The operator of a double-rotor trowelling machine is sitting on the seat in the cabin and driving it.  Thus, human contact with the smoothening surface is excluded and only the blades or disks of the trowelling machine touch the concrete. Such machines are self-propelled ones.

Topping is one of the types of finishing or strengthening the surface layer of concrete floors.  Topping floors are widely used in industrial and warehouse premises because they are free of charge and easy for operation. Besides, the topping floors are cheaper in comparison with the alternative type of concrete surfaces like polymers or strengtheners on water basis.

The technology of erection of topping floors is that topping is inserted into newly-laid concrete and, immediately after its smoothening with rod and initial smoothening with helicopter using special carriages for topping insertion, the dry solution shall be smoothly poured out onto the skin surface and, the topping shall be rubbed into the foundation with the trowelling machines. Thus, creation of topping floors is directly connected to trowelling. The topping itself is a dry solution basing upon quartz (cheaper option) or corrode toppings having higher price but longer durability. Besides, topping may be in various colors.

In the process of laying the semidry skin, after putting the sand-concrete solution, the trowelling machines start smoothening and simultaneously compacting the newly-laid solution.