The following articles are taken from the MC aktiv publication and curated by Buidling Chemical Supplies Ltd. Content contained is therefore the property of MC-Bauchemie Müller GmbH & Co. KG.
The sea ling and repair of the Mrawan railway tunnel in Jemba, in the east of the island of Java, had already been attempted several times without success, before MC submitted its proposal in response to a project tender issued by the state railway authority.
The tunnel was completed in 1902 during the Dutch colonial period, and exhibits a masonry stone arch with a thickness of 90cm. In all the earlier attempts to repair the structure, water seepage through the soil above constantly gave rise to leakages through the tunnel roof. The-Tuong Do, Business Development Manager for South East Asia at MC. realised that an efficient and permanent repair of the tunnel could on ly be achieved with complete gel ling of the crown, that is to say the upper third of the tunnel arch. He therefore recommended that a curtain be injected behind the tunnel arch with the soft elastic sealing injection resin MC-lnjekt GL-95 to provide a permanent water barrier. "Drilling through the natural stone bricks with their various thicknesses was difficult. The packers had to be extended through to the soil to ensure that the injected hydro structural resin would create a leak-tight curtain around the tunnel arch;' reports civil engineer The-Tuong Do. There was no road access to the tunnel, which made the logistics of the job significantly more difficult. In addition, work could only be carried out between 2 a.m. and 6 a.m. Thanks to the outstanding properties of MC-Injekt GL-95, the injection work brought the desired success, despite difficult climatic conditions. And because of the controllable reaction time and reversible swell ability, the applicators were able to adapt the injection system to the varying soil conditions. The bore holes were sealed with MC's fibre-reinforced PCC concrete replacement Nafufill KM 250.
The repair of cracks in the inspection tunnel serving the Jatibarang rockfill dam in Central Java represented a further challenge, with high-pressure bodies of water additionally hampering the work. The structure serves both as a storm barrier and as a source of local water supply. MC and the Indonesian application firm PACA, which has been working with MC product systems for many years now, were called upon by the general contractor PT. Wijaya Karya, a company well acquainted with the expertise that MC can offer in the field of tunnel injection. Following a site inspection, the MC team recommended a two-stage injection system to solve the problems prevailing, and this was then implemented. The water ingress was temporarily stopped by the rapidly foaming injection resin MC-lnjekt 2033, with the cracks then being injected and permanently sealed with the elastic resin MC-Injekt 2300. With a high degree of professionalism, problem-solving expertise and outstanding product systems, MC was therefore able to produce impressive results in relation to both projects, thus attracting further attention to its capabilities from within the marketplace. Further enquiries from dam operators have already been received.
The Blanka road tunnel complex is currently the Czech Republic's largest subterranean building project. It comprises two one-way road tunnels with a combined length of around 12 kilometres running under the surface infrastructure of Prague's downtown district. This ambitious construction project, underway since 2007 and now nearing completion, will be Europe's longest metropolitan tunnel.
The Blanka tunnel not only features two carriageways for road traffic but also a sophisticated ventilation system and various water drainage ducts. It is being built using both the cut-and-cover and tunnel boring methods. Needless to say, it is essential that the tunnel be reliably sealed for long-term integrity as the build progresses. Consequently, MC injection systems are being used for repairing leaks in construction and expansion joints, and also water-carrying cracks, in line with the stringent requirements of this mega project. With the quality of MC products already widely known, these injection systems were specifically selected by the general contractor and the application companies responsible. The soft elastic sealing injection resin MC-lnjekt GL-95 TX, for example, is swell able and thus ideally suited to sealing cracks, voids and cavities, even under conditions of permanent water contact. It also adheres well to plastic waterproofing membranes and is suitable for wide-area curtain injection. While MC-lnjekt 2300 plus was used for the repair of water-carrying cracks, it is also suitable for sea ling applications in dry conditions. This elastic sealing elastomer injection resin offers an impressively rapid rate of volume increase which nevertheless comes to a halt after an appropriately short time. Both resins are suitable as repair barriers for waterproofing against penetrating moisture. In the case of water under pressure, the low-viscous elastomer foam MC-Injekt 2033 was injected prior to the permanent waterproofing seal. This injection resin reacts quickly, causing it to foam and expand with a high rate of volume increase. Aside from the road tunnels, the Blanka project also encompasses other structures such as the new Trojsky road bridge, in which the specialty resin MC-Ballastbond 70 is being used for solid ballast bonding and soil strengthening.
These elastic sealing elastomer injection systems are also being used for sealing and repairing the underground station Narodni and the extended Route A underground railway line. While, in the Metro station, water-carrying cracks, voids and cavities, and also (cold) construction and expansion joints of the tubing elements have required sealing, in the Route A extension, cracks were encountered in the tubing, as were leakages in the other stations. Wider areas of water ingress are also being injected in the Motol underground station with MC-Injekt GL-95. Special MC services are likewise in demand for this project, with the applicators being trained and supervised as they carry out their work on site.
In the ground under Kuala Lumpur one of the world's most extraordinary tunnel project is being carried out – a combination tunnel that is intended to take surface water run-off and traffic simultaneously. In the Malaysian capital, during the monsoon season between November and March each year, dramatic floods cause damage that affect the population and cost millions of dollars. Moreover, the expanding metropolis has to deal with increasing traffic. The government required a solution to solve both problems. That's how the innovative SMART project emerged (Stormwater-Management-And-Road-Tunnel).
The tunnel with a total length of 9, 700m and double ducts integrates a floodwater canal for a length of around 3,000m. The rest of the year, the large tunnel with a 13m diameter serves as a tunnel on two levels for cars and trucks crossing the city. During the strong monsoon rains the tunnel can be closed to traffic and serves to channel sudden downpours underground in order to prevent floods or at least to reduce them.
The project was assigned to Malaysia's largest construction company MMC-Gamuda as main contractor. While Gamuda itself constructs one of the tunnels with a length of 4,100m Wayss & Freytag lngenieurbau AG was given the subcontract for the construction of the second tunnel of 5,300m.
For such large projects, a lot of safety issues have to be considered and planned for beforehand. One of these functional constructive measures is injection in order to ensure the sealing of water leaks as stipulated in the contract. For such applications MC injection systems have proven to be suitable as effective measures on similar projects such as the 4th tunnel under the Elbe and the Westerschelde tunnel.
Willie Kay of MC Singapore and Gareth Lewis of MC Malaysia presented to, and were successful in convincing, the project management of Wayss & Freytag that MC's approach to the problems of tunnel leaks is the most effective. Leaks can occur in the surrounding rock, between the segments and through the segments themselves. The concept is one of providing not only the right materials but experience, skills, onsite training and service from one source, namely MC.
The company Harvest was recommended by MC for the application of MC products on site. Their employees had successfully completed the IRP (Injection Repair and Protection) training course. A significant construction to the success was Rafael Sass' presentations and guidance on all practical matters. Rafael is the senior application technologist at MC Bottrop.
In September 2004, the north side of the tunnel offered the possibility to demonstrate by a trial injection on leaking ring joints using a hydro structural resin through a variable ratio, two-component high-pressure pump. The sealing of cracks in the lining segments could be carried out successfully with elastomer resins using a one component high-pressure pump. Thus the Wayss & Freytag project management decided to use MC injection products on all subsequent injection work.
The successful completion of the work resulted in MMC Gamuda's decision to also use MC products for the construction of the other tunnels. It is anticipated that the project will be completed according to the Malaysian government's requirements by December 2006. This project is clear proof of the acceptance of MC products on international projects worldwide.
The Orinoco, with a staggering length of 2,140 kilometres, is the third largest river in the world and a famous Venezuelan icon. In the south-east of Venezuela, approximately 500 km from the capital Caracas and near Puerto Ordaz, the Venezuelan Government is building a bridge over the Orinoco river for road and rail traffic. Construction started at the beginning of 2003, with the contract for the 3.5 km bridge having gone to Odebrecht lngenieria y Construccion de Venzuela.
Problems arose in 2003 during the preparation of foundations for some of the concrete piers. The sub strata, in some areas, was composed of sand and silt in and made excavation very difficult. A solution had to be found to solidify the ground at a depth of 90 metres using injection techniques.
At that point it was impossible to tell whether the ground would pose further problems during on-going construction procedures.
Odebrecht Venezuela asked the Brazilian laboratory, Furnas Centrais Eletricas, to find a solution to this particular problem. Various products were evaluated, including those manufactured by MC. After extensive testing only Centricrete UF delivered convincing results and MC was awarded the contract to supply material for the necessary injection works. Coordination and project assistance were given by Waldomiro Almeida Jr and Jaques Pinto of MC Brazil, in consultation with Manuel de Sa of MC Germany.
The injection operations took place in 2004 under the supervision and guidance of the Venezuelan authority, the Corporacion Venezolana de Guayana, who recorded all test results and compiled the final documentation.
The stabilisation of the ground was achieved by the use of 'jet grouting'. This method feeds injection rods into the ground, then a rotating jet stream mixes the loosened particles with a cement suspension and thus stabilises the ground.
In one location 4.5 m3 of Centricrete UF was injected via a jet-grouting-system in only an hour and 24 minutes. Subsequently the loss of water under pressure and the penetration of Centricrete UF into the surrounding ground were measured.
In total the project required 50 tons Centricrete UF, which were imported from Germany. Due to time pressure 10 tons had to be sent by air-freight, the remaining 40 tons were shipped by sea.
The opening of the 3.5 km long Orinoco Bridge is planned for 2006. It is bound to become one of the most beautiful postcard images, but more importantly, the Orinoco Bridge is at long last going to connect the many regions on either side of this state.
The Portuguese Island of Madeira has a breathtaking mountain landscape that attracts many ramblers and mountaineers. About one and a half hours flying time from mainland Lisbon, the Atlantic Island of Madeira measures 794 square miles and lies just off the west coast of Africa. The island's population totals 250,000, with 100,000 living in the island capital Funchal.
A total of 45 road tunnels through mountainous regions connect Ribeira Brava and Machico. The motorways and tunnels on Madeira are managed by Vialitoral - Concess6es Rodoviarias da Madeira S.A. This is a consortium of operators that was partly privatised in 2000 and consists of Madeira's autonomous regional government and Portuguese construction companies and banks.
Inspection of seven tunnels showed cracks in the concrete forming the vaults. In 2003 the consortium therefore decided to put out to tender a total of 4,940 metres of tunnel repair works.
Professional advice from MC allowed the project management, Betar from Lisbon, to present expertly drafted specifications in August 2004. Injection technology was the preferred choice to restore the integrity of the concrete of tunnel soffits. Trial injections by different manufacturers were undertaken. MC successfully provided comprehensive individual and effective solutions in every area that posed problems, thus impressing the contractor and winning the contract. Especially in the field of injection technology MC remains unbeaten and number one in the world.
A total volume of 30 tonnes of injection resins and cleaning agents were used. The project commenced in January 2005 and is estimated to be finished in September of this year. Works are conducted through Tecnasol FGE Fundacoes e Geotecnia S.A. from Lisbon.
Water-bearing cracks are sealed with elastomer resin MC-Injekt 2700 L and dry cracks with duromer resin MCDUR 1200 VK. Joint sealing is done using the highly flexible MC-Injekt GL-95 TX via two-component high-pressure injection pump technology, MC-1200.
Director Fernando Godinho, sales manager Carlos Cardoso and application technician Luis Antunes are the MC team, at hand at all times for advice on the project.
The company Tecnasol FGE, who have been applying Mematerials in Portugal for many years, have been able to further their technical expertise during this project. Gaining the "IRP Certificate" at the international vocational training centre in Krefeld, they invested in the future of their company through personnel development, thus ensuring that even the most difficult projects can be professionally and successfully completed.
Thanks to the sophisticated injection technology from MC Madeiras tunnels can again be used safely and can be protected from future damage for years to come.
The Oester Valley Dam in Germany's Sauerland is situated roughly seven kilometres from Plettenberg. It was built between 1904 and 1907 by the then "Dam Pope", Professor Dr. Otto lntze during the era of the so-called 'heavy load construction type'. A curved dam wall built from quarried stone masonry with a high percentage of mortar forms the base area. The use of the water's power to produce electricity was of central importance for the economic development of the region in those days.
In the years between 1889 and 1914 a total of 40 dams were built based on the lntze-Principle. However, nowadays new findings question the safety of this type of dam structure.
In 1948/49 the first repairs had to be carried out on the Oester Valley Dam, to repair the joints on both the up stream and down stream sides.
In 1960 the spillway-crown was hardened with a new specialist grouting material and re-painted to about ten metres down. After that further repairs were unavoidable in 1968, 1987 and 1995, but the repairs were not durable. During the 1990's noticeable damage from leaking water and deformation on the downstream side of the brickwork demanded rapid action from the Oester Water Board, which operates the dam.
The first measure taken in 2000, was blasting an observation gallery into the brickwork in order to carry out vertical sealing injections of masonry and subsoil from this gallery. Here sicotangrouting mortar VP-1 Trass HS was used with great success. The pre-wall casing made from heavy basalt cuboid masonry was greatly deformed especially from the downstream face and the joints were extremely worn and weathered. So that loadbearing and fitness-for-purpose could be preserved for the future, the masonry had to be repaired as well. The old mortar joints were removed to a depth of 15 cm using high pressure hydraulic jet technology and were refilled with sicotan spray mortar SM-TK HS.
At the joint on-site acceptance, also attended by Manfred Scheidt as sicotan consultant, the engineering company "Projektwerk" based in Netphen stressed the good cooperation between the companies involved in the project. Thanks to modern injection technology it had been possible to successfully restore the Oester Dam.
Based on these experiences it is highly likely that many dams built in the "lntze-way", will need to be repaired in the years ahead and will need to be brought up to date in terms of technology - an area of great potential for MC.
The economic development in south east Europe offers interesting market potential, particularly in the specialist area of "injection technology".
The core activities in Serbia revolve around "water supply and tunnel construction", as this is an area in which there is a great need for repair. A decisive factor for MC's collaboration with the tendering authorities was the high quality standard of MC products and the expertise of MC staff. Dragan Jovanovic as Site Advisor and Walter Jacke, Injection Project Manager, assisted in finding suitable solutions for projects.
Based on positive experiences with the hydroelectric power station Djerdap other such power plants now also use MC technology.
MC sales representatives locate the key contacts and exchange ideas on concepts with neutral experts on site. One of their primary points of contact is the Hydraulic Engineering Institute in Belgrade. A close cooperation has been established with the head of the institute there, which accommodates MC's technological objectives. An injection seminar following the Bottrop model has been held there this year, which saw the participation of the construction departments from the larger hydroelectric power stations. The event was highly successful resulting in a number of interesting projects.
The cooperation with the Belgrade Hydraulic Engineering Institute has prospered in the meantime to such an extent that MC is now advising on every injection project and has also acted jointly as an expert team in negotiations with potential clients. Today the institute principally recommends MC product systems for any kind of problem in the area of injection technology.
The second key area “tunnel construction” is also gaining importance. Negotiations are currently being conducted with the south Bosnian Railway Company in Sarajevo, regarding the repair of brickwork and concrete tunnels. The aim here, too, is to establish MC as a regular partner from design through to tender and execution.
Optimal customer benefit requires a high degree of commitment and competence from every single employee and this is what ultimately determines MC's success. For this reason qualifications and further professional development of its employees is given the highest priority at MC and are well enshrined components of the personnel strategy of the company.
When new sales representatives take up their posts, they bring with them sound professional qualifications and numerous individual experiences, however, every new position poses a new challenge to individuals which they have to adjust to and for which they need to be prepared.
It is standard practice at MC to give new members of staff thorough and detailed training before they take on their new responsibilities, irrespective of where they are being employed. Thanks to our own internal training centre, the good infrastructure and the proximity to many instructors, such training takes place in Bottrop. The possibilitie shere are ideal to teach theory, give practical demonstrations and show application in practice. Furthermore it gives staff, whose new place of work is not at the headquarters in Bottrap the chance to get a picture of their company and its product range and to get to know the relevant departments involved.
Responsible for all English speaking training is Elmar Lohe. The graduate engineer coordinates all training events and implements these assisted by the various specialist departments. He explains MC's training concept in this interview with MC aktiv.
The concept, which has been successfully used for quite a few years now, ensures that every new sales employee/ specialist advisor receives basic training at the start of his employment that will provide him with the necessary knowledge about specialist topics and product groups. As MC's sales operations are divided in two separate specialist areas, Protection Technologies and Construction Chemicals, separate training sessions are organised for either field. Events in 2006 include the four large subject areas of concrete restoration, injections, industrial flooring and concrete admixtures as well as training seminars about Oxal and Nafuflex all of which were conducted in German and English.
Participants come to Bottrap from all MC sites located across the world, resulting in a varied cultural mix during these training sessions.
Due to the steady international expansion of MC, now including Bulgaria, Romania, Ukraine, Southeast-Asia, or Brazil, the number of new employees has grown so large that the basic training cannot always coincide in time with the commencement of the new position. To counter this drawback, the "Train the Trainer" programme was conceived at the end of 2005.
For this programme long-serving and experienced members of staff- predominantly sales personnel or technicians - from all MC sites are selected, who then perform the basic training locally. These employees receive thorough preparation for their task from Elmar Lohe in Bottrop within the scope of the "Train the Trainer" programme.
These seminars don't just cover technical content, but rather tackle induction procedures for new employees that will give them the best possible preparation for their new positions. This includes, amongst other topics, information about MC's sales and distribution strategy, its company philosophy, how contact ought to be made with potential industry partners and who the decision makers are - internally and externally. Also addressed are country-specific requirements and conditions.
To convey technical content pre-prepared, standardised expert lectures about selected MC product areas are at hand, such as injections, sewage/ wastewater systems, bridges and tunnels, which assist in instructing the new employee on technical details relevant to his/her sphere of activity. However, the focus here is not on technical knowledge, but on customer's benefits. These documents, compiled in Bottrop, ensure that the training is conducted anywhere in the world following a unified corporate concept.
The participants of the "Train the Trainer" training thus perform the function of multiplicators, who conduct the initial training locally until the new employee can take part in the scheduled basic training in Bottrop.
To allow for the extensive expansion of MC in Russia, a separate local training centre has been established there. With the help of government funding a centre for concrete technology (ZBT), in the mould of the Bottrop archetype, has been opened this year. As this facility offers also the possibility to conduct technical demonstrations and trials, it not only serves as a training centre for employees but also doubles up as an event venue for customers and visitors. The centre has the advantage that competent local instructors can train MC employees in their native language.
The aim of the programme is to equip competent members of staff in our world-wide locations with the right tools to give new staff the best possible induction for their future jobs- in line with MC's corporate philosophy. This takes the pressure of the training centre in Bottrop and optimises vocational adjustment. Since the training programme is still in its infancy, Elmar Lohe also has the task to check the viability of the concept at local levels and to support his colleagues
The fact that even a good product can get better is proven by the latest development of MC-Bauchemie: The renowned low viscosity of elastomer injection resins has been considerably improved with the new version of MC-Injekt 2300. Now sealing injection is possible even more quickly and safely in extremely fine cracks, movement joints and cavities.
The protection of concrete structures against the penetration of aggressive substances and the creation of an impermeable barrier require low-viscosity, permanently flexible injection materials, which can accommodate crack movement. The experience of four decades of successful development work is bundled in the new MC-Injekt 2300 top system.
The MC-Injekt 2300 marks a high technical standard since the beginning of the 1970s. This elastomer- based development fulfilled the requirements of a flexible, very ductile crack sealer. With the innovative combination of elasticity and controlled pore formation, MC had already set a technical standard back then, which still exists today. The controlled pore formation provides a basic ductility to elastic materials with a low modulus of elasticity.
Further developments followed, which improved the application properties (viscosity, water hygiene safety, REACh, etc.) and the permanent functionality (glass transition temperature, permanent flexibility). In this way, MC has continually raised the technical level when it comes to injection with elastomer resins.
To make all these properties become effective in a structure, the inject ability of the resin is a prerequisite. This is largely governed by the resin's viscosity. Now, the latest development by MC, is superior to all previous products.
The injection properties of the new MC-Injekt 2300 top resin are highlighted by its extremely low viscosity. With a viscosity of only 55m Pas, it is significantly lower than any other comparable elastomer- based injection resin. The flow ability and therefore penetration of the resin were developed by formulating to modify both surface tension and viscosity. A high level of penetration of fine cracks and capillary cavities is possible with low injection pressure. Using MC-Injekt 2300 top to seal against water ingress is done with a maximum of safety for the structure.
For resins, which are used specifically against water, the moisture compatibility is of particular importance. Elastomers are essentially compatible with moisture, however, they can embrittle if there is only a partial reaction with water. MC-Injekt 2300 top does not behave in this manner and exceeds the requirements of the relevant standards regarding change in properties over time when in contact with water and in an alkaline environment by 50%.
It goes without saying that critical issues relating to contact with ground or potable water also apply to injection systems. MC-Injekt 2300 top has been tested and complies with the Federal Environment Agency's guidelines for assessment of organic coatings in contact with potable water. MC-Injekt 2300 top meets health requirements for plastics in contact with potable water. According to the current REACh regulations MC-Injekt 2300 top can be applied without endangering human health or the environment in given exposition scenario.
In summary, MC-Injekt 2300 top opens up a new dimension in flexible injection resin performance. Never before a solvent-free, flexible and pore-forming elastomer based injection product was available with such low viscosity. In addition, it copes with all relevant environment-specific requirements. Cracked and damaged concrete elements can be permanently sealed against water while simultaneously steel corrosion is prevented in reinforced concrete. Cracks and cavities will be safely sealed independent of the present level of moistness.
Next to the actual sealing properties, the low viscosity has a positive effect on the injection process as inject ion can be carried out at lower pressure without putting the result at risk. For the applicator, time savings as a result of the easier and quicker flow of the resin offer economic advantages. These advantages are made fully usable with a two component injection pump. As MC-Injekt 2300 top has a 1 - 1 mixing ratio of A: 8, wastage as a result of mixing complete packs and not being able to use it during the pot life is eliminated.
Tunnel construction is one of the most fascinating - and at the same time one of the most difficult - tasks in civil engineering. The construction methods and safety measures must take into consideration the geological conditions of the area. The materials used in tunnel construction are also subject to special requirements with regard to stability and water impermeability. Cracks are undesirable here, and yet due to movement within the structure caused by internal or external influences, aging material and unforeseeable circumstances, cracks cannot altogether be prevented. The joint design, a necessary requirement in terms of construction, is of lasting importance. Joints are an essential part of a tunnel structure and are always subjected to permanently high stress.
Cracks and leaking joints pose a permanent potential hazard. As early as during the construction phase of the tunnel shaft, water leaks and an unstable foundation can jeopardize the structure. Cracks and joints allow water ingress which may damage and deteriorate it. The penetrating moisture limits serviceability and under the added influence of frost leads to further defects and spalling.
MC, as competence leader in the area of injection technology, offers innovative solutions that enable permanent repairs of such structures. The objectives of injections are the stabilisation of the foundations, the creation of a water tight environment, the protection against ingress of corrosive pollutants and the reliable waterproofing of the joints. The areas where MC injection systems can be used are very diverse. Tunnels are nowadays constructed with concrete. In the old days they were generally lined with brick. In order to address the different construction- specific conditions MC offers products based on different resin combinations that are customized to suit the given individual requirements.
With decades of experience in all areas of application and continuous research and development MC sets trend-setting benchmarks. A reference list with a record of global clients and projects attests to the performance success of these system solutions.
On Madeira, a Portuguese island in the Atlantic, traffic is directed via a total of 45 tunnels through the extremely mountainous region. An inspection discovered cracks in the vaulting masonry of seven tunnels. The operating company decided to tender the restoration of the tunnels. The remit was to restore the degraded concrete in the vaulted area of the tunnels, using injection technology. During trial injections MC solutions were the most convincing. Repair work was carried out in 2005, consisting of an order volume of approximately 30 tonnes of injection resin. Water-bearing cracks were injected with the duromer resin MC-Injekt 2700 L. Joints were sealed using the hydro structure resin MC-Injekt GL-95 TX. The two-component pump technology was used in this case.
A particular challenge for MC was its involvement in one of the most exceptional tunnel projects in the world. At the end of 2006 a unique combination tunnel was completed in Kuala Lumpur, the capital of Malaysia. Known as the SMART tunnel it is designed to channel both vehicle traffic, and storm water. Projects of this scale demand the implementation of numerous safety concepts. One of the functional- construction measures were injections to ensure the tunnel's leak-tightness, particularly in the area of the segments and their associated ring joints. To this end MC Malaysia submitted a detailed concept for an ali-in-one solution. The leaking ring joints were injected with hydro-structure resin using a variable ratio two-component high pressure pump. The sealing of the cracks in the segment joints and segments was successfully carried out using a single- component high pressure pump and elastomer resin.
The current injection project "Katzenbergtunnel", EfringenKirchen, also needed emergency waterproofing. Leaks occurred during the construction phase in the area of the segment joints. They had to be sealed in order to ensure the agreed water impermeability. Based on test results, real life applications and the longstanding performance values the MC injection system MC-Injekt GL-95 TX-TR has been accepted as the system for segment joint injection. The works are expected to last until the end of 2008.
Besides their application in modern tunnel projects injection methods have also been used in the restoration of historic structures. Heidelberg's cable car, which started operations in 1907, needed to be waterproofed in the area of the drip-wet natural stone vault in 2004. In the three tunnel sections between the base station and "Am Schloss" station the historic mortar in the horizontal joints had been extensively damaged-by frost. In addition the entire internal walls showed surface damage from moisture penetration. The contract comprised waterproofing, insertion of drainage and protection measures against frost. Again, based on prior tests the hydro-structure resin MC-Injekt GL-95 proved to be the ideal solution. In total 80 tonnes of the soft elastic injection material were applied using the injection pump MC-1200 vario.
The success of injections rests on the optimal interaction between people, machinery and material. For this reason an intensive collaboration between system and product suppliers and experienced application companies is of particular importance. To increase communication and also the position of partner companies the "Fordergemeinschaft lnjektionen", an association for the promotion of injections, has recently been formed in Switzerland. Since injection measures vary in terms of material, cause of damage, condition of structure and injection objective, the association can recommend competent partners who have the required technical knowledge and experience to take all factors into consideration.
Bond Street in London, the Rue du Faubourg Saint-Honore in Paris and the Via Montenapoleone in Milan are considered top addresses when it comes to exclusive fashion houses. With "Fashion Street," Budapest is also entering the ranks of European fashion capitols. In the city centre, valuable properties were painstakingly renovated to provide the luxury brand fashions with the requisite ambiance. Hungarian MC-Bauchemie engineers and applicators advised the client on material selection and application.
Property developer, Immobilia Plc developed the concept of Fashion Street at the turn of the millennium. The company wanted to create high-quality retail trade and office space in historic buildings. The first project was the reconstruction of the Deak Palota (Deak Palace), which began in 2003. This was built in 1903. It was extensively renovated and equipped with state-of-the-art fixtures, fittings and plant.
The Deak Palota has a usable area of 4,800m2, which is divided into five office levels and two commercial floors. Tenants include the European Parliament and the European Commission, who set up their Hungarian office. The commercial sector includes international fashion corporation Hugo Boss, which is among the largest in Central Europe.
Since its reopening in June 2004, the Deak Palota has served as a flagship project when it came to the further development of Fashion Street. The concept of setting up high-quality branded articles in Budapest's pedestrian zone also convinced additional investors, who wanted to revive the city centre. For example, in 2003 a Louis Vuitton shop opened its doors. Countless other exclusive brands followed. As a result, "Fashion Street" is no longer just a row of houses but an entire city district, which is dominated by exclusive brand businesses.
Most of the available houses were historical properties from the 19th and early 20th century. They were completely gutted and then extensively reconstructed based on historical examples. MC-Bauchemie's products and their specialized expertise were in demand for this purpose. Most of the buildings had damp cellars and foundation walls, as there was no known technology for effective and permanent sealing of the cellar area when they were built. Because the new usage planned to create some stockrooms in the cellar areas and, at the same time, the original building materials needed to be protected from penetrating moisture, a high value was placed on finding a reliable sealant concept during the repair works.
Against this background, Csabo Petho, Sales Manager for Construction Chemicals at Hungarian MC-Bauchemie Kft., was able to convince planners and decision-makers of the advantages of the Oxal system. Together with his employees, he developed an exactly co-ordinated solution for each project based on thorough damage analysis. During the building work, employees of MC were regularly on-site to provide applicators with advice and support their quality management.
For example, when repairing the Palazzo Dorottya, which was converted into a fashion boutique and apartment block, Oxal SPM waterproof mortar was used for the sealing works. It can be used on wet and salty foundations and is characterised by a high resistance to sulphate and reduced water vapour permeability. In addition, Oxal DS-HS sealant slurry was used, which also offers strongly reduced water vapour permeability. To create sustainable horizontal damp proof barriers, the two-component Oxal L70/H30 injection system was used.
The Oxal system could also satisfy demands in the old stock exchanges, the Gucci and Armani saloons. When repairing the Casino Hotel and the Parisi Nagagyaruhaz, products from the Nafuflex range were used, such as the two component, polymer-modified bituminous thick coating Nafuflex 2K-SP and Nafuflex 245, which were both designed for the building work sealing using a spray method.
With these renowned projects on Fashion Street in the heart of the capital, MC Hungary has been able to reconfirm that it is the national market leader in the field of sealing systems.
Since 2004 the German motorway BAB 17 has been Europe's longest trunk road, connecting Dresden with Prague. Two tunnels, Coschutz and Dolzschen, form part of this motorway and are located in Dresden's congested urban area. They run beneath Dresden's city districts by the same names. After five years in operation injection solutions from MC-Bauchemie were used as part of the repair measures to remove damp defects.
The most complex and expensive structure of the BAB 17 sits on the 8.8km long stretch between the Dresden-Gorbitz exit and Dresden-Sudvorstadt, consisting of two tunnels and a bridge across the WeiBeritztal. The two three lane tunnels Coschutz (2,332m) and Dolzschen (1,070m) are equipped with ultra-modern safety technology and even today count as some of the safest tunnel structures in the world. Up to 75,000 vehicles drive through this section every day. After five years in operation water-bearing segment joints had to be sealed. Based on its long-standing experience in tunnel repairs, MC-Bauchemie was ordered by Saxony's motorway authority to supply a suitable injection material that was able to detect and seal the finest of water flow paths.
Based on inspections a couple of years previously with regards to the particularities of temporary water loading a product form MC was chosen which had been developed for such application scenarios: the soft-elastic polymer-enforced hydro-structural resin MC-Injekt GL-95 TX.
While standard injection gels can only be used in permanently damp surroundings, this specialist resin forms a skin-like layer that protects it from drying out even in normal ambient air conditions, thus ensuring permanent waterproofing function. In total 100 tons of MC-Injekt GL-95 TX were used in the repair of both tunnels.
The injection measures had to be performed in both traffic directions without interruption to traffic as the surrounding roads were not meant to be burdened any further. From September to December 2009 work continued every day from 6pm to 6am. During this time one lane was open for traffic in each direction, with two lanes closed for repair. The only problem was logistics, as the closure of lanes resulted in less than optimal conditions for the delivery of the material into the tunnels. Andreas RoBner and Dieter Biehl from the MC-Service-Center Leipzig advised motorway authority and engineers and assisted the executing company DMI lnjektionstechnik GmbH based in Berlin in the injection works onsite.
After successful completion of the repair works this part section of the BAB 17 can now be used without restrictions. The injections thus ensure the high safety standards in the Coschutz and Dolzschen tunnels, rated by the German break down association ADAC as "very good", are maintained.
The inadequate disposal and treatment capacities for waste and wastewater are among the biggest environmental problems for Mumbai and its 12.5 million inhabitants. Technologies are required that repair existing systems with minimum effort.
Especially during the four month monsoon period floods put a big strain on the few systems. Refuse carried by the rainwater blocks rivers, which leads to a partial breakdown of the system. As a result of this drinking water and wastewater often mix causing the spread of infectious diseases.
Moreover, many of the existing systems are badly in need of repair. In order to at least prevent further deterioration, MC injection technology has been used lately. In the district of Mahalaxmi the wastewater department commissioned the repair of a drain running underneath a railway track, whose stability was in great danger and exposed to infiltration and ex-filtration due to numerous cracks in the masonry. The oval brick wall of the duct, dating from the colonial era, was reinforced by injecting MC-Injekt TS-07 into and behind the wall into the foundation.
The injection system is a structure reinforcing resin that can be injected into fine-pore media due to its excellent water-like low viscosity properties. Thanks to the controllable reaction time, the injection material can be adjusted precisely to the local conditions and the previously calculated penetration depth can be reached. The quick hardening of the material, undisturbed by moisture and dynamic vibrations was necessary because of the immediate vicinity to the railway track. This was a decisive factor for the success of the project.
The brick-built storm water channel walls in Mahalaxmi were therefore strengthened and water proofed. In addition, MC-Injekt TS-07 formed a pressure-resistant conglomerate where the drain interfaced with the surrounding rock. The structure thus strengthened by injection technology was then lined with shotcrete from the inside and coated with the sulphate resistant repair mortar MC-RIM. The section in question was able to be rapidly put back into service.
The A2 motorway is one of the most important north-south transport axes in Europe and one of the most heavily used motorways in Switzerland. Every day thousands of cars and HGVs pass along the route, which runs from Basel via Luzern, Altdorf and the Gotthard to Lugano and Chiasso. Drivers also pass through the Grancia Melide Tunnel in Ticino, which is currently undergoing repairs with MC-Injekt GL-95 hydro-structure injection resin produced by MC.
New safety regulations have meant that restoration work is now needed on the Grancia-Melide Tunnel (built in 1968) and its two 1680-metre long, two-lane tunnels. Constructed using mining techniques prevalent at the time, the tunnel does not have any waterproof layer. Until now, the water coming down off the mountain has accumulated behind the in-situ concrete cladding, from where it is then drained off. At the top there is a false ceiling, in which three ducts allow air to flow in and out. During the course of the restoration works, the false ceilings and cladding will be removed to enlarge the usable space.
These actions make it necessary to waterproof the tunnel at the points where water penetrates through cracks, joints or other defects. The technique is the hydro-structure resin curtain injection" process. This process fills and seals the cavity of the permeable contact zone between the concrete and rock face. This is being carried out by the Cadenazzo-based Sika Lavori firm using 2 component injection pumps. The benefit of MC-Injekt GL-95 is that its reaction speed can be precisely adjusted to the particular task, depending on the degree to which water is penetrating", explains Daniel Stirnimann.
The demand for energy is growing throughout the world. Sources of energy have to be cost-efficient but increasingly sustainable too, so renewable energies are on the rise. In this context, the majority of countries are witnessing less and less construction of hydroelectric power stations. However, in regions with plenty of water there is a focus on using dams as a method of producing energy. Examples in this respect can be found in Brazil and Portugal, where MC-Bauchemie too is involved in mega projects- both in construction and restoration. For within the energy sector, MC is acknowledged all over the world as an expert partner, rated highly for its excellent products, practical know-how and unique level of on-site service.
A gigantic wall that stretches endlessly- viewed from below it appears to ascend to the very heavens- holding back vast quantities of water, as far as the eye can see. Dams have a tendency to strike awe into the observer, and they are without doubt some of the most impressive structures built by human hand. Even merely looking at them conveys an idea of how much planning, know-how and work goes into building them. The vast preparatory works, such as the establishment of the infrastructure long before the walls of the dam or any of the ancillary structures are actually built, can themselves require many years to complete. The quantities of concrete needed are simply immense, while the demands made of the concrete can vary greatly from one region and project to the next. This presents a tremendous challenge to the client, the architects and the applicators, as well as to the manufacturers of concrete admixtures and the technical chemists.
Brazil is growing- and with it the hunger for energy, particularly in the nation's economic centres. Brazil is also looking to export energy, which is yet another reason why the energy sector is flourishing. Fully 97 percent of all energy generated here is produced from hydro power, explaining why over ten dams are currently being built in the north and north-east of the country, in order to ensure that the continuously growing demand can be satisfied into the future. One of the largest major dam projects is located on the Rio Madeira, a tributary of the Amazon. The Jirau dam hydroelectric power plant is designed to generate 3,750 MW of power. The energy will be produced by horizontal bulb turbines, installed into the bed of the Madeira. These will be driven solely by the flowing power of this huge river. The construction is currently reaching its completion. Representing an investment of over 8 billion US dollars, the dimensions of the project are huge; over 20,000 workers were on site during the height of the construction phase. Right in the middle of the Amazonian wilderness, a fully functioning town was established around the construction site. MC too made its contribution to this highly prestigious project.
With two newly established plants -one in Sao Paulo and one not far from Recife in Vit6ria de Santo Antao with production facilities and a dedicated sales team, in this burgeoning country MC -Bauchemie Brazil is acknowledged not least as a specialist in the construction, restoration and maintenance of hydraulic structures. Its clientele include prominent energy companies specialising in hydro power.
The strategy of MC Brazil is to be close to its customers, focusing on the potential-rich energy sector. Construction Chemicals and Protection Technologies each have one staff member dedicated to the issue of dams and hydro power. And the heads of sales, Shingiro Tokudome (CC) and Jose Roberto Saleme (PT), also look to delivering customer-dedicated services, a feature that typifies MC's approach worldwide.
Unique service and specialist expertise are qualities also demonstrated by MC in connection with the government-funded Jirau project, the construction of which also saw the use of MC admixtures, as well as PowerFiow plasticiser, for example.
Working closely together with the consortium, the regional government, the environmental department and the energy companies- including the international energy group GDF Suez-, MC developed admixtures and special solutions, appropriately adjusted to the climatic, geological and technological circumstances and base materials, and matched to the stipulated performance specifications.
MC-Bauchemie is supplying expertise and materials to another major dam project, this time in Portugal: the Baixo Sabor dam is designed as a mountain water reservoir located on a tributary of the Sabor River. The project was started in 2008 and is scheduled for completion in the summer of 2014. Energy will be produced with the turbines being driven by the large drop in height travelled by the water. An important project for the nation, it is also an exciting project for MC that comes with certain challenges.
The client, Energias de Portugal (EDP), specified that the rubble produced by the dynamiting be used for the concrete. The initial tests consequently performed for the development of the formula found that this basic material would result in a product that would lock in a great deal of water, meaning that the concrete would scarcely A ow To deal with this problem, the consortium consulted with the University of Porto, with which MC also regularly exchanged information. Ultimately it was MC that succeeded in taking the basic material to arrive at a specialised 8 I MC aktiv 1_2013 formula, which enabled it to deliver a solution in the form of a modified MC admixture. "Standard off-the-shelf materials are no longer adequate for the majority of projects", says Diana Boulhosa, Head of Sales for Construction Chemicals at MC in Portugal. Since that time, the water-reducing admixture, TechniFiow, has been used in the construction of the structures adjoining the dam wall.
Even given the long lead time of this large-scale project, the identification of solutions suitable for the project only commences once the basic materials have been specified. But even after the formulae have been developed and tested in the concrete la boratory, it is advisable to subsequently modify them to the situation on the construction site. For it is possible that the products may behave differently when exposed to different conditions - such as the effects of weather - or when scaled up on site. And here again the experts from MC come to the fore. "When we develop and market an admixture, we always seek to apply the formula we arrive at on site, in order to prove that the product can actually perform under real conditions," emphasises Dr. Thomas Sieber, Head of Technical Advice at MC
MC's experts engage in an active exchange of knowledge and empirical results - and this is reflected at an international level too. The findings identified here are applied to the benefit of the customers and the company itself. Commissioned in mid-2012, a further plus is the ultramodern production plant in Bottrop that enables MC to offer PCE-based admixtures from initial development to finished product- all from one single source. The patented product ion process permits a high degree of customisation and Aexibility in the manufacture and composition of the admixtures, from which partners in the construction industry can benefit MC is involved in the construction and restoration of hydraulic plants across the world: including in Scotland with the Lower Glen dam (top left), in Brazil on the Santo Antonio (top right) and in Russia on the Sayano-Shushenskaya dam (bottom left) or in India on the Jammu dam (bottom right) the best admixture for their particular construction project.
MC also delivers outstanding quality in the restoration of hydraulic structures, particularly dams.
Products developed by Protection Technologies can be found in the restoration of hydraulic structures throughout the world, such as in New Zealand, Germany and Russia- but also particularly in Brazil. From 2009 to 2010 some 50 smaller hydroelectric power plants went online there, after having leaks repaired with injections to allow them to be handed over "dry" to their operators. MC was awarded the contract in many of these projects, not just because the relevant project planners were convinced of the quality of its injection product systems, but also because of its high level of application know-how, first-class support and the tremendous expertise of its employees. And that is what distinguishes it from the competition. "A successful restoration project in the order of a dam or valley reservoir is critically dependent on atriumvirate: material - machinery- people", states Holger Graeve, Injection Group Leader at MC, looking back on his wealth of experience in this area. "It is our qualification courses and application training, conducted in the relevant national language that in particular demonstrate our expertise and deliver significant added value to our partners. Hence, we pay clo.se attention to maintaining our network of planners, principals and applicator greatly, because they receive precisely firms."
Whether Construction Chemicals or Injections, the same principle applies: every partner receives specifically tailored support For example, MC's employees assist planners in drafting invitations to tender, advise principals on their projects and provide support to applicators in the deployment of product systems. MC also has a team of technical advisers ready to provide practical assistance and advice anywhere in the world. A comprehensive service of this type does not come into being overnight Now, with MC's high-grade product systems and tremendous application know-how, better solutions for the construction and restoration of dams- and many other structures that demand qualitatively high-value and long lasting solutions are readily achievable.
Dams, valley reservoirs and other hydraulic structures are only able to withstand constant water pressure on their broadsides if leaks, cracks and cavities are promptly repaired. So sealing them is a top priority job. For this purpose MC has developed a whole series of solutions unlike any other in the world.
Whether it be in the generation of energy, the control of high waters, the production of drinking water or for shipping- hydraulic structures are constantly important for people, industry and the environment. Their durability and efficiency is closely linked to the strength and impermeability of the masonry and the concrete, which have to be able to withstand constant water pressure. And large-sized leaks not only reduce the stability of the structure, they also result in a significant loss of energy in hydroelectric power plants. Over time it is practically impossible to avoid smaller leakages in the masonry or concrete in structures of this size. However it is essential to conduct regular maintenance, i.e. measures for protecting, reinforcing and sealing.
The remit of injection systems is to provide the structure with reliable protection against the penetration of water and the damaging materials it contains, as well as to prevent corrosion. In some specific cases, they are also required to stabilise the supporting sub-surface and the construction components. Water impermeability is achieved by sealing construction elements, including all joints and surfaces.
MC is a leader in elastomer resins. These resins are primarily used for the elastic sealing of cracks and for cavity filling, and so contribute to keeping structures functionally reliable. They also have particularly good environmental and water tolerance qualities. With their specific properties, the various solutions developed by MC fulfil the most diverse requirements. Plus, not every crack is the same as the next. Its particular features, such as progression and width, the conditions of the sides of the crack, its cause and any previous measures undertaken, are all factors to be taken into account. Choosing the right product means having to visually inspect the problem and perhaps taking a sample of the core if necessary. A strong unit: test injection of a foundation subsurface strengthened with MC-Injekt 2700. Blocking holes effectively MC keeps things tight Cracks have to sealed elastically if found in structural elements that may still be mobile. This can be performed using rubber elasticised MC-Injekt 2300 top. MC-Injekt 2700, on the other hand, creates a rigid seal against larger ingresses of water, for larger cavities or for stabilisation of the structure. This friction-type, glass-hard duromer resin is stronger than concrete. Its rapid and superior effectiveness stops ingressing water immediately. MC-Injekt GL-95 TX, a hydro-structure resin, is used for the watertight filling of cavities and settlement joints exposed to water pressure, as well as for large surface area injection into structures or in the foundation subsurface. Its degree of deformation is almost rubber-like and it bonds extremely well to concrete. The functionality of this system actually requires constant contact with water. By using a specifically aligned injection packer, which is braced in the drill holes of the structural elements, the selected product can be injected with a suitable pump.
Thanks to their outstanding injection properties and rapid, controllable reactivity, these elastomer resin products from MC will continue to enjoy success.
The Maastunnel Rotterdam is one of the oldest road tunnels in the Netherlands. It has two tubes reserved for vehicle traffic and two for cyclists and pedestrians. It was constructed between 1937 and 1942 and it connects the banks of the Nieuwe Maas, a main distributary channel of the Rhine-Maas delta. Due to the geographical circumstances and the method of construction, it is prone to frequent penetration by water. A continuous challenge, and one mastered with MC know-how.
Around 75,000 cars, 4,500 cyclists and numerous pedestrians pass through the 1,070 metre long Maastunnel daily, making it one of Rotterdam's main transport arteries. So the city cannot afford to have a situation where the tunnel is out of use for any length of time. Leaks and other damage are consequently repaired quickly frequently by using product systems, advice and practical know-how supplied by MC. As was the case last year. In August leaks were detected at the tunnel entrances, which lie 7 metres below the water level: large quantities of water- 6,000 litres per hour - escaped through each of the 5 metre long joints of the tunnel entrances and these had to be swiftly sealed in order to secure the tunnel and make it safe for its users. The City once again decided in favour of an MC product system, MC-Injekt GL-95 TX, which had already been used successfully in the past in stopping leaks and sealing joints. Because the tunnel had to be closed for two days for the work, the time restriction was extremely pressing. By working closely with one another, all those involved in the project overcame the challenge with flying colours. One significant factor in this success was the high quality of the work delivered by the applicator firm, Tebccon of the Netherlands. The technical solution having been defined in advance, it was possible to bore the holes for the packers on the first day, with the material being injected during the next.
MC-Injekt GL-95 TX is a two-component, polymer-strengthened hydro structure resin, which, through its particularly low viscosity and high reactivity, can be injected into large cavity spaces as well as fine-pored subsurfaces. The product possesses an highly reversible degree of deformation and it bonds supremely well with concrete and many other construction materials. These qualities make it the ideal product for sealing joints and surfaces exposed to high water pressure meaning it was also the perfect product for dealing the joints at the entrance to the Maastunnel. Thomas Robbe and Hervy Bosman, from MC's service team based in the Netherlands, provided on-site support to the entire project and were on hand to deliver practical advice and assistance.
In order to carry out the injection works, after a detailed consultation the Tebccon company deployed relatively large packers with a 100 mm diameter along the joints. Injection pumps were then used to inject over 7 tonnes of MC-Injekt GL-95 TX. As soon as the hydro structure resin began to extrude from the joint, the flow of water abated before ultimately petering out completely. The problem of the leaks at the joints of the tunnel entrances was successfully remedied in this way, but the tunnel, which is somewhat long in the tooth, will face such problems again in the future. So repairs are an ever-present issue. Provided such problems can be overcome using products such as MC-Injekt GL 95-TX, there is nothing to prevent its continued use.
The Maastunnel in Rotterdam connects the two banks of the Nieuwe Maas and is a significant transport artery. Leaks at the tunnel entrances and exits were repaired by injecting MC-Injekt GL-95 TX.
Preventing leaks is of major importance when it comes to keeping tunnels in service. Consequently, ageing tunnels need to be regularly repaired and resealed. And also when it comes to the construction of new tunnels, injection operations are frequently required as part of the work.
You just have to look at the dimensions involved when constructing a tunnel using the tubbing method: 10 km of tunnel requires around 400km of joints between the segments and rings. Joint leakages and damage when installing the tubbings cannot always be avoided in work of such magnitude. Although the elastomer frame gaskets that embrace the tubbings are becoming increasingly sophisticated, there is still a danger of leakage resulting from the installation process. Lack of fitting precision due to placement error is indeed one of the most frequent causes of leakages. There is a particular danger of misalignment at the tubbing corners where heavy contact at the gasket profiles can cause the continuity of seal to be interrupted. Subsequent correction is virtually impossible. Once the tubbings have been installed, leakages can only be stemmed by injection using an appropriate sealing product. Both joints and cracks have to be rendered accessible through the introduction of injection channels. However, these are usually quite difficult to create in such highly reinforced concrete components.
The injection work needs to be carried out as closely as possible to the joint or crack. In classic applications, this is usually achieved with packers that pump the sealant through the injection channels into the unsealed area. A patented method has now been developed for the sealing of expansion joints with profile seals whereby the medium is injected directly through a monitored compaction channel across the compressed profiles. This can be performed without adversely affecting the compression of the frame gasket and therefore its leak-proofing effect. The injection materials that have proven most suitable for a tunnel repair are polyurethane-based elastomer resins and acrylate-based hydrostructure resins of low viscosity and short reaction times. Elastomer resins such as the two-component, flexibly sealing injection resin MC-Injekt 2300 top are particularly suitable for sea ling cracks of only minor width change, providing lasting leak-proofing irrespective of the moisture levels encountered.
Swellable hydrostructure resins on the other hand, are more suited to Joints where there are larger dimensional changes. These need permanent water contact as a prerequisite for their unique, fast-swelling capability. The polymer-modified, soft-elastic injection resin MC-Injekt GL-95 TX is readily formable and mechanically stable. It exhibits similar water impermeability to that of water-impermeable concrete and can be relied upon as a joint sealer. Injection products from MC are used for wide range of construction projects - not just tunnels. The injection resin MC-Injekt 2700, for example, both sea is and strengthens during production of the start and end manholes, reliably repelling pressurised water. It serves to consolidate crevices and voids in the rock while at the same stabilising the subsoil. An injected sealing ring comprising the soft-elastic injection resin MC-Injekt GL-95 TX provides a shield tail seal during tunnel heading work, protecting the transition zone of a tunnel boring machine between the manhole and the subsoil during maintenance, and minimising downtimes.