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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.

Specialist expertise for the repair of moated castles

Maintenance and repair measures are essential from time to time to ensure that century-old moated castles are kept structurally sound and appealing in appearance for posterity. The right expertise and suitable product systems are essential for such work. And both are available from the Oxal division of MC.

The regulations governing the protection of listed buildings mean that repairing historic structures is a very demanding undertaking, not least because the restoration work also invariably has to ensure that the original appearance is fully retained.

Due to the proximity of water, moated castles naturally encounter frequent problems involving very damp masonry and thus also exposure to salts. This adversely affects not only the render but al so the entire structure. In order to restore the functional and visual characteristics of both, product systems are required that are specifically tailored to ensuring durable results under such conditions.

Grosskmehlen moated castle - lasting protection despite water exposure

The company Schlosser GmbH of Potsdam, Germany, is responsible for the upkeep and maintenance of a particularly heavily soaked historic monument, the Grosskmehlen moated castle in the south of Brandenburg, Germany. Huge problems were identified in the course of repair work being carried out on the buildings there. The new render applied to the base of a carriage house had already begun to show signs of damage after just a short time. As the previous measures implemented had not brought the desired success, Schlosser GmbH began looking around for new solutions to the problem - and came upon MC-Bauchemie. Klaus Schindler, a sales engineer working for Oxal in Brandenburg, inspected the situation on site and recommended Oxal's moisture-regulating render Exzellent. The decision was taken to initially apply Exzellent to a sample section of the carriage house in question. After a trial period amounting to two whole years, the treated surface still exhibited no signs of deterioration. This led Schlosser GmbH, in consultation with the architect responsible, to choose Exzellent as the render for all the damp areas. The special pore geometry of this moisture-regulating render causes it to extract the moisture together with the dissolved salts from the masonry to its air-side surface. It is up to 15 times more efficient in this than hydrophobic repair renders, and this process will not damage either the underlying masonry or the render itself.

The repair project began in May 2013 and was completed in September of that year. The entire ring wall containing the moat was covered inside and out with the white machine applied render Exzellent 600, with the areas of the castle close to the water being rendered with coloured Exzellent 700. In addition, all the foundations of the ancillary buildings were provided with white trowel-applied Exzellent 610.

"We encountered particular challenges in having to apply thicknesses of up to 10 cm around the ring wall. Although Exzellent with its low as-applied weight and high basic stability allows thick coat application, we had to find a special solution in this case;' says Klaus Schindler. After consulting Dr Andreas Zahn, Head of Oxal Sales, it was therefore decided to level the unevenness with an undercoat of Oxal SM TK. This joint refilling mortar is open to water vapour diffusion and exhibits outstanding edge bonding with natural stone masonry. This coating was followed by 3 to 3.5cm of Exzellent, which was then roughened with a grated scraper. The result is a particularly even surface, leaving the project promoters delighted with the results achieved.

Authentic appearance for Banska Bystrica moated castle

The challenges encountered with the Banska Bysrica moated castle near the Slovakian town of Zvolen were rather different. This castle, built as a fortress in 1576, had already largely fallen into ruin, with the last owner having abandoned it in 1978. Originally it had a rampart wall with four turrets and a moat with a drawbridge, and was built as a means of protection against Ottoman attacks. For the new owner, the company Vodny hrad s.r.o., there was no choice but to opt for a complete reconstruction in order to return this renaissance castle back to its former glory. The main priority for the owner was to restore the ramparts, walls and other structural components to their original appearance. For this purpose, Oxal RM, a special splatter coat with a natural stone appearance, was selected. Thanks to its good application properties, this is ideally suited both to the rock imitation and also the delicate re-sculpting work. The outstanding quality of the mortar impressed the contractor, lng. Rajnoha. All the areas that originally consisted of natural stone were replicated in this project in accordance with their original appearance using Oxal RM, with various colour shades being prepared on site as required. The contractor was so delighted with the material properties and the versatility of Oxal RM that the same render was also ordered for construction of the imitation stone bases, paving slabs, steps and stairways, balustrades, facings, fireplaces, etc. The reconstruction of the moated castle is proceeding very well, with completion scheduled for 2015.

Authors: klaus.sch &

Oxal division

The Oxal division offers a comprehensive portfolio of systems for structure waterproofing and historic building repair and restoration- from bituminous thick-coat systems, horizontal barriers and sealing slurries to a range of renders. These include not only Exzellent but also other product systems for the creation and sculpting of facade elements- including and specifically those of historic and listed structures:

Restoration renders such as Oxal WPw which, in combination with waterproofing measures, provides a reliable and visually attractive solution for the restoration of a building's fabric.

Lime renders such as Oxal mineral-based lime render are used as base and finishing coatings open to water vapour diffusion. They are ideally suited to the restoration of listed buildings with low salt and moisture exposure.

Historic renders are cement-free and can be used selectively for the repair and refurbishment of historic buildings.

Pulling mortars such as Oxal coarse and fine pulling mortars are used for the creation of internal and external profile cornices, and with the aid of templates for the profiling of walls.

Ornament grouting compounds such as Oxal Ornamentguss rapid, our rapidly curing grouting compound for the creation of ornaments, replicas and figurines, particularly on facades.


County Courts Lublin

'Oxal Project' Wins Award

In the last edition of MC aktiv we reported briefly on the Oxal range, the new addition to the MC family of products. An exciting and successful example of its application is the project to renovate the county courts in Lublin, Poland.

What does one do when a building has passed its sell-by date, the cellar walls are damp and the facade cracks? A few 'cosmetic repairs' won't give lasting results and extensive refurbishment measures are usually needed to preserve such a structure.

The Oxal range offers the redeveloper a broad spectrum of building preservation measures as well as customer services tailored to the individual project. The basis of the comprehensive package is an initial site inspection, resulting in a detailed analysis. More-over, Oxal offers support with the drafting of the individual specifications, supports the redevelopment at every stage and trains the workforces of contractors involved in the project.

The County Courts in Lublin are an excellent example of an extraordinary redevelopment project.

Lublin is a university city with 340,000 citizens, of which 50,000 are students, and is one of the larger cities in Poland. The County Courts are situated in one of the more affluent parts of Lublin. They were built in the 19th century and had deteriorated to such an extent that redevelopment became unavoidable. At the end of 2003 the Ministry of Justice contracted ARCUS, a Lublin specialist redevelopment company for historic buildings with the overall redevelopment of the court buildings.

Due to well-established relationships and connections, and the many excellent references detailing prior successful cases, MC Oxal department was given the opportunity to visit the site and take samples of the brickwork, which they tested for dampness and salt content. These tests were undertaken in collaboration with the Department for Old Building Preservation of the Technical College in Lublin. Based on the results a comprehensive redevelopment concept was worked out, which formed the basis for all subsequent works.

Danube Bridge

Almost the entire range of Oxal products was applied during this project. The order included: wall sealing, horizontal waterproofing in the cellars, as well as the complete re-plastering of the cellars and facades, plus coloured finishing coats. The work was rounded off with a final treatment of the front of the building with 'Emcephob', the latest surface protection system.

Wojciech Wereski of the MC subsidiary in Poland was the consultant responsible for the building execution; he took part in technical acceptance dates, attended meetings regarding the overall co-ordination and trained the work-force of companies performing the works.

Finally, at the end of last year, the historic building was rein-stated to its former glory. It duly received official recognition for excellence, being awarded 'The Golden Laurel' by the Heritage Department for a restoration project done to perfection!

Natural stonework repairs with volcanic materials

Oxal, one of MC's specialist departments, has expanded its product range with the integration of Sicotan.

When structures, such as castle walls, dams and bridges built with natural stone need to be repaired, mortars based on trass have a proven record of success. This natural volcanic material is economically and ecologically significant as it possesses a wealth of technical advantages. Used as an admixture in mortar it improves workability, prevents lime efflorescence and discolouration. Trass mortars have a low E-modulus and are open to water vapour diffusion. The Oxal range for natural stone repair comprises joint mortars for hand application and wet and dry spray application. They are suitable for natural stone, clinker & clay brickwork.

Different colours allow for a perfect match with the substrate. A specially coordinated brick and paving mortar is available for external and internal areas, which is also suitable for gypsum-based brickwork. The pressure and injection mortar is used when filling in cavities and to reinforce natural stone brickwork. The trass-based mortars with high sulphate resistance are thix-otropic and flow easily. They are applicable over a range of substrate strength classes such as those found in natural materials.

With mortars on a trass basis, the Oxal department has a product range for natural stone repairs at its disposal.

Studying in the Stable

On the premises of the former Vom-Stein Barracks in Osnabriick the former stables there have been converted and restored by the local Technical College to house the study course Technical Information Technology.

The former artillery barracks had originally been the stables for army horses, built between 1901 to 1903, with an adjacent office and storage area, which was partially extended in 1910. The parts converted now form the northern border of this historic barracks compound which is a listed building - a fact that to be taken into consideration during the execution of the works and which influenced the selection of product systems.

Army Barracks Stable to Technical College

The specialist department Oxal in particular offers a range of complete solutions for the restoration and preservation of buildings that have been matched to perfection. They enable developers much simpler planning and the builder owner a scientific, lasting alternative of highest quality standard. The advisory service includes the damage analysis on site, advice in the design of an individual restoration concept and continuous assistance during the execution of the measures.

The historic stable building was made of natural stones and bricks. The penetration of crystallised salts led to joints and brickwork breaking away, damaging the building fabric dramatically. A fundamental restoration had become unavoidable in order to restore the building for use. Based on the tender specifications by the architects Scholz-Hunepohi-Ferner and the on-site advice by MC advisor Rolf Cremer the WTAapproved Oxai-Wertputzsystem was selected as the ideal solution.

Following the substrate preparation of those parts in direct contact with the ground, the walls were sealed with the sealant slurry Oxal DS-HS. Unevenness of up to 4cm was levelled using Oxal SPM. Finally, the air-pore rich Oxai-Wertputz was applied, which serves as a salt container layer. This complete solution package ensured the flawless drying of over 2,700 m2 of brickwork. More than 80 tonnes of Oxal products were used in this restoration.

Now there’s lively hustle and bustle of young students where horses were once looked after.

Castle Restoration with Oxal

Brick wall injection saves Hungarian monument from dereliction

Modern Hungary has still plenty of historic buildings and landmarks dating back to the glorious reign of its former monarchy. The capital city of Budapest is characterised by magnificent buildings and historic sights.

The surrounding area has a lot to offer in this respect, too. Approximately 50km from Budapest is the small town of Bajna, home to the “Sandor Metternich Kastely”. This castle, built in the classicistic style, once belonged to count Moric Sandor. He was known as the “Devil’s Rider”, his famous riding stunts being the talk of Europe.

His daughter, known as Countess Pauline Metternich following her marriages to her mother’s brother, played a significant role at the social and cultural events in Dresden, Paris and Vienna during the second half of the 19th century.

After the Second World War the castle was declared government property. As it was never assigned any lasting purpose, the building increasingly fell into a state of disrepair over the years. Due to its historic importance it eventually became a listed building with Hungarian Heritage status. In 2004 the Department for Hungarian Heritage decided to restore the façade of this magnificent castle, so that it could be rented out or sold.

Architekton Ag, specialising in such restorations, was awarded the contract. Over the years dampness had weakened the brickwork to such an extent, that only brickwork injections with Oxal HSP-ME could repair the extensive damage. Architekton called on MC’s support, as MC is well-known for its specialist expertise in the repair of brickworks and its highly effective products and technology.

Castle Renovation

MC Hungary was involved in this project right from the start. Csaba Petho was present on-site and assisted the operators in the analysis of the brickwork, during the execution of works and finally during quality control.

The walls were enormously thick – almost one metre – which posed a bit of a problem. Injection channels had to be drilled from both sides of the wall to enable injection from either side. The thorough training of the Hungarian operators, specially trained by MC technicians in horizontal barrier injections using the low pressure method, ensured the professional execution of works.

Following the successful completion of these repairs the façade was ready to be given a new finish. In compliance with the criteria for listed buildings this was done using the original, historic formulation for the plaster, which was specially mixed on-site.

The facade of the castle now shines resplendent in its full glory. All it needs now is an investor, who is willing to restore the inside of the building, including many beautiful mural paintings.

Preserve the Past and Give it a New Gloss

800 years of history have had an extreme impact on some of the buildings of the Frankfurt Historical Museum. After a thorough restoration, the gleaming buildings were reopened in May 2012.

The Historical Museum heritage and memory of Frankfurt

Anyone looking at the Historical Museum now will be truly enthralled by the restoration works. The persons responsible have succeeded in renovating the buildings with materials and colours from the time that each was built. The restorer Hans-Michael Hangleiter has performed tremendous work on behalf of the Historical Buildings and Monuments Department of the City of Frankfurt. In doing so, he was able to rely on the support of MC's Oxal specialists, who contributed to the success of the project by delivering the right product systems.

The problem: dampness and salt

The Museum is located right in the centre of the city, not far from the Rbmers district and close to the River Main. There is permanent dampness in the masonry, and unfortunately this cannot be avoided. "Due to the location a full drainage operation could not be considered", explains Gerd Bott from the MC Frankfurt Service Centre. The damage caused by the moisture through the years was all too apparent during the on-site inspection: the saline pressure had drastically attacked the plaster and in part already destroyed some of it. The rising damp meant that the internal walls were also affected. Following an extensive documentation of the current status, it was clear to all that it would be impossible to halt the penetration of moisture and salt into the structure.

The solution: allow it to pass through

This was the challenge presented to the Oxal Department, possessing as it did a rich wealth of experience in structural waterproofing and the restoration of old structures and historical buildings. Developers, planners and contractors were able to make use of an extensive product system. In the particular case of the Frankfurt Historical Museum MC's specialists looked to a plaster system that, unlike conventional restorative plaster systems, does not block structurally damaging salt constituents, but with its unique pore geometry transports these to the surface of the plaster. "The continuous transport of salt helps prevent damage to plaster and masonry caused by Frankfurt Historical Museum: Faithful restoration, permanently protected crystallisation", explains Gerhard Bott, before moving on to explain the additional benefits: "With the high calcium content both in the aggregate as well as the binder and the specific porosity, this plaster system has a moisture regulating and climatising effect." Furthermore, there is no build-up of moisture and the plaster counteracts the spread of mould and is resistant to salts, such as chloride, sulphate and nitrate.

Excellent products

The best product for the vault and the outer base proved to be Exzellent 600 while the trass chalk grouting mortar, Oxal SMTK, was selected for the stone-faced masonry. Due to the acceptable pigmentation of Excellent 600, no subsequent paint system was applied which further aided the transport of salt and water. Over 1,000m was coated during this phase. The material was spray applied in several layers. The thickness of the coats sometimes exceeded 5 centimetres. A classic example of MC's modern technology being used to develop an extremely robust and durable mortar.

Baroque palace restored and permanently protected

The baroque Oranienburg palace in the centre of the town of the same name in the state of Brandenburg was regarded as one of the most beautiful palaces in Prussia when it was built some time around 1700. Today it is home to a museum, the registry office and the municipal council chambers. The ravages of time and the permanent penetration of moisture have left their marks.

Baroque Palace

The facade of Oranienburg Palace has been afflicted with constant dampness for years now, without the problem ever having been tackled effectively. Numerous attempts to seal the masonry, including with trass mortar, all failed. It was therefore understandable that the supreme heritage protection authority of the State of Brandenburg and the building control executive of the Town of Oranienburg were sceptical about undertaking a new attempt. The problem was readily evident during an on-site inspection. "Because nothing at all had been done to date to waterproof the structure, on the one hand the masonry was exposed to precipitation, while, on the other, the surface water from the higher-lying terrain could seep in unimpeded," reports Klaus Schindler, Oxal expert at MC's Berlin Service Centre, who headed up the project together with his colleague Jens Biermordt. The dampness that rose from the floor led to the masonry being exposed to extremely high moisture and saline loads. "We therefore recommended that we first treat a sample area with our moisture regulation render, Exzellent, and observe the results over the autumn and winter period," explains Jens Biermordt.

Exzellent stands up to the test

Building Restoration Before

"In this case it made sense to work with Exzellent, because it exhibits a unique pore geometry and is able to absorb the moisture With the aid of a specially made template, the sample piece was reprofiled using Exzellent- with a result so convincing that it was subsequently used to restore the entire wall already present in the masonry and transport it, and the harmful salts it contained, unimpeded to the surface of the render. It is also highly suited to plasterwork tasks;'explains Biermordt, who, as a stucco plasterer and restoration expert, has a wealth of experience in the restoration of historical structures. The specialist prepared customised templates for the profile grooves of the walls, applied Exzellent and observed the sample area over a period of six months. The result was convincing -in the spring of 2012the test area looked impeccable. The decision was therefore taken to restore the lower section of the wall at the front of the Palace.

Building Restoration Before Coating

Comprehensive support

The objective now was to define the restoration concept and the technical plan, as well as to match the original colouring of the wall as much as possible. Jens Biermordt is particularly proud of the fact that the light-grey coating -specially mixed for this job exhibits a colour accuracy rate of 98%. At the client's express wish, the two Oxal experts provided extremely close support during the restoration works. "We were on site several times a week to instruct the application workers, to check the building sections and to take part in the formal acceptance of the works;' says Klaus Schindler looking back at two months of work centring on the 130 metre long and 70 centimetre high wall. During this time, in which several coats were added, some 104 kg of Exzellent was applied per running meter.