Process for reconstruction of buildings with the wet-mix shotcrete in a thin-stream system

The wet-mix shotcrete process has been developed in the years 1966 to 1969 and this time the system was completely new. This time as well as today from the Experts and the tunnel- and mining industry requested quality standard would be fulfilled by this technique. With this process, the concrete will be constructed by injection to the underground of the object (Building) in all positions, that means vertically, horizontal and overhead.

In accordance to the attribute of the process, buildings and other objects can be constructed by an essential lower cost as the conventional technique. By this technique, reconstruction and! or intensification of objects is possible. Buildings can be reconstructed where the conventional method is not any more possible. Also the objects can be reconstructed under normal working condition of the correspond to the building.

According to the reached results of the reconstruction-system in praxis, we are very confirmed that in conformance with the reconstruction measure the cost will by essentially reduced. For example, through problem solution which are partly possible with these reconstruction systems only.

A number of Objects which have been reconstructed by this procedure has proved and confirmed by scientific investigation. By this investigation the main concentration of the tests are the bar- and surface structure to single direction and single axis load, to the load resulting from bending and pure tensile load against grip resistance and cracking.

Reference and scientific evaluation belonging to the system are in our hands. Up today a area of approximately 46000 m² has been reconstructed by this procedure.

This procedure is a wet-mixed shotcrete system in thin-stream way with regular compressed-energy by keeping all the condition and facts to fulfil the requirements of DIN 1045, as well as DIN 18551.

This system allows a dimensioning of the concrete to the higher concrete-class. A grip-combined between the old existing-construction and the new concrete-reinforcement will be reached, which will be an important function to take and guarantee the load-caring and load-distribution.

A concrete or mortar are installed which will be processed in a high-active compulsion mixer.

The following will be achieved.

• The homogenising of the mixture with the various components, such as aggregate, cement, water and, if necessary, concrete additives.
• The solubilising of the cement grain through the exactly proportioned addition of the quantity of water required so that the cement grain can form the cement paste, thus ensuring the cohesion and adhesion which is the prerequisite for the placing and adhesion of the shotcrete and sprayed mortar. In addition, the pore volume is considerably reduced during hydration.
• Exact compliance with the water-cement ratio (e.g. 0.40) which is the prerequisite for achieving high concrete qualities.
• An optimal encasing of the aggregates with cement and water and simultaneous integration of any concrete additives possibly used. (Concrete additives if such are used).
• No formation of dust during placing or spraying on the sprayed material, as the causes of the formation of dust, such as fine parts in the aggregate, cement or dry concrete additives are bound by the water. In this manner, the MAK threshold values (MAK = Maximum Workplace Concentration) laid down by the liability insurance agency complied with.

To sum up, it may be stated that here we have a reconstruction system available which demands to the requirements of concrete-repairs according to the following facts in the highest degree:

• Through the maximum process of mixture.
• Through the high compression of concrete by the wet-mixed shotcrete technology in thin-stream. -Using a concrete technological high-grade reconstruction materials, normally without chemical additive (BE).
• Under consideration of all concrete technological factors.

Our technology are used in the following areas:

Mining:

Extension of underground sections, mine shaft, caverns and where concrete is used without casing.

Tunnels:

One-way construction, reconstruction of roads- and railway-tunnels as well as underground railways.

Civil engineering; underground and surface levet construction with three aims:

• protection of caring-load construction from existing buildings for the interest of prevention to outside damages.
• to reinforce existing construction which has lost the load-ability for any reason. Reestablishment of the load-ability respectively increasing the load-ability for demands of more load.
• to erect such new load caring construction which according to there specials forms or arrangement, which must be concrete without or with casing bat no other solution will be fund.

Up today, in different fields of application, a lot of structural- and reconstruction activities with this technology has been carried out. For example, the reconstruction of approximately 16.000 m² steps and balconies, 10.000 m² ceilings in private buildings and 20.000 m² ceilings, beams and bar-structures in industrial buildings.

For the restoration of four railway-tunnels with increasing of the profile as well as the extension and reconstruction of underground hollow space with cross section from 12 - 76 m² has been carried out by the system. The system used also to reconstruct cooling-tower, bridges, viaducts, pillars, beams, ceilings, balconies, steps, support-walls, rock- and hillside protection, reinforcement of foundations, water-tanks for drinking-water-distribution, sewage drainage, harbour installations, historical buildings under protection of monuments etc. This procedure and the technology is also usable for special constructions from steel-shotconcrete structure and for processing of insulating-material in a region of heat- and cooling-technology.

British Railways has adapted the procedure under licence for reconstruction of its bridges, tunnels and certain structure, as well as for construction of new tunnels.

A lot of this works has been co-operate and accompanying with the following institutes:

• Universität Bochum, Institut für Konstruktion, Ingenieurbau, Lehrstuhl für Bauverfahrenstechnik und Baubetrieb, Ordinarius Prof. Ing. B. Maidel.
• Technische Universität Budapest, dem Lehrstuhl für Stahlkonstruktion, Prof. Dr. Halasz
• der STUVA (Studiengesellschaft für unterirdische Verkehrsanlagen Köln, Dr. Schreier)
• der Erbrobungsstelle 52 der Bundeswehr, Oberjettenberg, Schneitzelreut
• dem Staatlichen Materialprüfungsamt Nordrhein - Westfalen, Dortmund
• der Tiefbaugenossenschaft, München
• der Bergbau - Forschung GmbH, Forschungsinstitut des Steinkohlebergbauvereins, Forschungsstelle für Grubenbau und Gebirgsmechanik, Essen - Kray
• KBFJ; Zentralinstitut für die Entwicklung des Bergbaus, Budapest
• EMJ, Institut für Qulitätssicherung

The sequence for the reconstruction is as follow:
After investigations of the existing safety of the object and the condition of architectural substance to the reconstruct~ building, the reconstruction activities will be draw up, according to the stress, single-axis, multi-axis, tensile load, compressive strength, on tensile load and compressive strength or on bending. The ascertaining and judgement to various facts like grip/shear resistance, shearing loadability, shearing strength, shearing stress, shear/elasticity modulus, compressive- and bending-strength, grip strength under thermal effect, E-module, shrinkage, water depth of penetration, Carbonation, Chlorisation depth of penetration, frost- dew- varation-persitent, Sulfat-resistance and Alcasation will be important. The documents with the scientific evaluation of this works are available and is part of the know how.

We hope that we have given you an overall view about our technology and we will be very grateful if we can expect an answer from your side. If you are interested on our technology we are ready for more information and conversation if necessary.
If you have no interest on our technology we would be very glad if you transfer this documentation to corresponding institution or contractors. Because we looking forward in your region for partners where we can benefit our technology.

We are convinced, that with this system the result of the rehabilitation to the earthquake damages will be very successful for all the participant.