We tear concrete, reinforced concrete and stone with hydraulic presses. A press is inserted into a pre-drilled hole.
Holes are drilled with diamond drills: 130 mm in diameter holes are drilled for a press the maximum tearing power of which is 110 t and 200 mm in diameter holes are drilled for a press the maximum tearing power of which is 250 t.
Two tearing presses can be inserted into one hole. Larger segments are torn by drilling 2 holes and inserting presses into holes in such a way that they both would tear in one direction. During the tearing process steel bars are torn loose or are stretched out and are cut with a gas cutting torch once the tearing press tears concrete pieces apart for 3–4 cm. If 4 tearing presses 200 mm in diameter each are inserted at once, we get the total tearing power of 1,000 t. In order to tear out a piece of concrete the cross-sectional area of which is 1 m2 tearing power of 15 t is required and 80 kg is required for tearing out steel the cross sectional area of which is 1 mm2. The power required for tearing out a segment depends on the amount of steel bars.
It is easy to calculate the necessary power, when a diameter and the number of steel bars are known.
Insufficiently vibrated concrete with poor strength characteristics is the biggest problem in tearing constructions of reinforced concrete. Although it sounds strange, it is much easier to tear high quality and properly vibrated concrete, as the biggest problem is that concrete crumbles as a result of pressure against it in the point where a press contacts with concrete, thus, the tearing power is not conveyed further on. The hydraulic concrete tearing station uses 380 V, 4.2 kW power.