Cementing process

The cementing process is a technique used in mining that serves to seal water-bearing cavities with the aid of cement . The cementing is the sinking of shafts used in aquifers. The method was used for the first time in 1900 by the mine director A. Wiede when he was digging the Pöhlauer Schacht.

Basics

When sinking shafts, water-bearing layers are often penetrated. In these mountain layers there is always strong water inflows. The water emerges from the mountains and flows into the shaft. As a result, the sinking work is severely impaired and, depending on the amount of water, comes to a standstill. Well drilling methods such as the Kind Chaudron method were often used for such mountains . The cementing process can also be used to create manholes at locations with fragile rock and rolling masses . Since the process also solidifies the rock, the process is also known as the petrification process . In the case of water-bearing layers, the water-bearing rock is also used for sealing by pressing in the cement suspension. The cement suspension reduces the flow speed of the water. As a result, the cement is deposited on the rock layers and gradually hardens. The water-conducting cavities are closed by the solidified cement, so that no more water can penetrate into the shaft.

Application and required equipment and tools

The method can be used either above ground or from the bottom of the shaft . Where the method is used depends on whether the upper overburden or the lower mountain is highly water-bearing. If the upper mountain layers are heavily water-bearing, the mountains are compressed over days. If the deeper mountain is heavily water-bearing, the cement suspension is pressed in at the appropriate points. One or more cement mixers, cement pumps and the manhole cement pipe are used as devices for the cementing device. The cement pump is used to inject the cement suspension. The cement mixers and cementing pumps are usually above ground and are only stationed on the shaft floor in exceptional cases. If the shaft depth is sufficient , the pump can be dispensed with and the cement can be injected by gravity. First, several holes are drilled at intervals in the rock. The number of holes varies depending on the mountain range. When used in the upper overburden, up to six holes are drilled. When used in the lower mountain strata, the number of holes depends on the local conditions. Standpipes are inserted into the holes. The cement manhole pipe is connected to the standpipes. A cement suspension is then pressed into the holes. Very finely ground cement is used for this. The cement suspension mixed from cement and water is also known as cement paste. The composition and the mixing ratio of water and cement must be calculated precisely.

Advantages and Limits

The cementing process has advantages over other processes such as, for example, in solid, water-bearing mountains. B. the freezing process . This is particularly due to the fact that the freezing process is only suitable for depths of up to 200 meters. In addition, fewer drill holes need to be drilled in the cementing process. The cementing process has further advantages in fissured rock . Here the cement paste penetrates well into the cavities and, after hardening, forms a dense and solid matter together with the rock. After hardening, a permanent water seal is created. In contrast to the freezing process, no expensive watertight shaft extension is required. However, the method cannot be used with gap widths of 0.1 millimeters and less. There are also problems when using the method in loose rubble, such as gravel with grain sizes of up to 63 millimeters and in sand . When used in the upper overburden layers from above ground , there is a high cement consumption, which can amount to several thousand tons , due to undetected cavities such as karstification .

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962.
^ ^A ^b ^c Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Ernst-Ulrich Reuther: Textbook of mining science. First volume, 12th edition, VGE Verlag GmbH, Essen 2010, ISBN 978-3-86797-076-1 .
↑ ^a ^b Friedrich Behme: The divining rod. Hahn'sche Buchhandlung Hannover, Hannover 1919, p. 106.
↑ ^a ^b ^c ^d ^e City Council Rosenheim: About the cementing process when expanding manholes. In: Deutscher Beton-Verein: Deutsche Bauzeitung, message about cement, concrete and reinforced concrete construction . 5th year, No. 9, pp. 58–60

[Quelle_1-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962.

[Quelle_5-2] A ^b ^c Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .

[Quelle_2-3] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Ernst-Ulrich Reuther: Textbook of mining science. First volume, 12th edition, VGE Verlag GmbH, Essen 2010, ISBN 978-3-86797-076-1 .

[Quelle_3-4] Friedrich Behme: The divining rod. Hahn'sche Buchhandlung Hannover, Hannover 1919, p. 106.

[Quelle_4-5] City Council Rosenheim: About the cementing process when expanding manholes. In: Deutscher Beton-Verein: Deutsche Bauzeitung, message about cement, concrete and reinforced concrete construction . 5th year, No. 9, pp. 58–60