With a new accelerated concrete curing system and 21 further steps to concrete pavers with triple protection

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1 Gerwing Steinwerke GmbH, Holdorf, Germany With a new accelerated concrete curing system and 21 further steps to concrete pavers with triple protection In the Wunderstein, Gerwing Steinwerke GmbH offers an innovative concrete paver from which even stubborn dirt can simply be wiped off. In addition, Gerwing guarantees a very high colour fastness that makes the stone look like new even years later. According to the company's managing director, Michael Gerwing, this is made possible by a completely newly developed triple protection in the core concrete, in the facing concrete and on the surface. Gerwing revised and optimised numerous processes in their concrete block paving production in order to achieve the desired result, which is now marketed under the name Wunderstein. There were 22 individual steps in total. One of them was the installation of a Quadrix system from Kraft Curing for accelerated concrete curing, which now ensures constantly consistent conditions for the curing of the concrete pavers the whole year around. Mark Küppers, CPI worldwide, Germany The Gerwing Group manufactures a finely balanced, full range of products for garden construction and landscaping with 60 employees at five locations in Germany. The production locations have a total plant and storage area of around 30 hectares. The high-quality garden block products are manufactured on modern machines using a self-developed system for constant quality assurance. Gerwing uses exclusively natural raw materials that are all fully recyclable. The main delivery territory for Gerwing is Germany; however, the Group's products also attract interest from beyond the country's borders. For instance, Gerwing has supplied coated concrete slabs for the outdoor areas of numerous McDonald's branches in Sweden. Production is focusing more and more on such concrete products with coated surfaces. Products that are no longer up to date are being deleted from the range. The company is thus reacting to developments on the market. Like other concrete plants, Gerwing perceives a change in the purchasing behaviour of private customers. Quality is becoming more important again. And in order to obtain it, people are also willing to pay correspondingly higher prices than they were years ago. Wunderstein "Oil stains on the drive or ketchup and red wine stains after a garden party can be removed from the Wunderstein very easily with a bit of hot water", says Michael Gerwing, describing the benefits of the new product. "And destructive algae and moss, which badly afflict conventional concrete pavers after only a short time, have no chance with the Wunderstein. Since it is also absolutely colourfast, the Wunderstein still looks like it has just been laid, even after years." Not only that, the robust Wunderstein has anti-slip properties and can also be driven over by heavy trucks without the coating being damaged. The company has tested that extensively. The coating is solvent-free. Quality is monitored constantly during production. The Gerwing concrete plant at the Holdorf location Before the installation of the Quadrix system the fresh concrete products at Gerwing had been stored in a rack system that wasn't enclosed, but stood open in the hall like the block making machine. 78

2 The new facing concrete mixer from Haarup, which was delivered together with new aggregate and cement silos. 22 steps to success "The development of paver production is comparable to other industries. There is no standstill, improvement is the goal. Just as vehicles are continuously being developed with new safety and comfort components in the automotive industry, the paver has developed from the rather practically oriented grey product that it once was into a valuable product that can only be manufactured using modern production equipment and the corresponding know-how", says Michael Gerwing, describing the evolution of the paver over the course of time. In retrospect, the road to the Wunderstein was anything but easy. Numerous processes, 22 in total, now run differently to the way they ran before. Each change had to be precisely coordinated with the other 21 so that every single one of the steps makes a contribution towards improvement. The 22 adjustments that Gerwing has made can be found in all areas of the production, for example in the mixing technology, the machine settings, the choice of raw materials, the temperature control, the selected coating media, the application technology, the packaging and much more.

3 facing concrete mixer, which is equipped with a dust extraction system. Gerwing produces its concrete products on a block making machine from Omag, which has already given many years of service. The block making machine has kept in step with the development of Gerwing's product range through regular maintenance and technical modifications. Checking of the fresh concrete properties Gerwing uses a control tool, the Qaver, to check the fresh concrete properties immediately following the compaction process. The compaction of the facing and core concretes can be measured independently of each other on the wet side. The Qaver also measures the product height and weight, from which it determines the gross density of the complete product. Gerwing uses a control tool, the Qaver, to check the fresh concrete properties immediately following the compaction process. The entire measurement process can be carried out quickly and simply by trained personnel. Precise control of air circulation, temperature and humidity "The processes have to work - irrespective of the plant technology", says Michael Gerwing, emphasising that the latest technology alone doesn't necessarily lead to good results. New facing concrete mixer for better and constant concrete quality The externally visible changes in the production include the new facing concrete mixer from Haarup, which was delivered together with new aggregate and cement silos. The aggregate silos in the outdoor area are completely roofed over in order to protect the raw materials from direct rainfall. The raw materials are dosed directly onto a conveyor belt located underneath the silos. The conveyor belt takes the raw materials to the mixer hall and transfers them to the bucket elevator. This elevator then transports them to the new The fresh concrete products at Gerwing had previously been stored in a rack system that wasn't enclosed, but stood open in the hall like the block making machine. Since the temperature and the relative humidity fluctuate considerably over the course of the year, the concrete products had cured under changing conditions until now. This process had to be optimised in order to be able to achieve increased quality in general and to be able to produce the Wunder - stein. The rack system had to be enclosed and the temperature and relative humidity kept at a constant, optimum level the whole year around. The company commissioned to implement this task was Kraft Curing Systems, which completely enclosed the rack system with 80 mm insulated sandwich panels and installed a Quadrix system for accelerated concrete curing. Kraft Curing Systems has completely enclosed the rack system with insulating elements. 80

4 CONCRETE CURING RACKS BY KRAFT CURING SYSTEMS INNOVATIVE SOLUTIONS ENSURE TROUBLE-FREE PRODUCTION THE K-PROFILE TWO LOAD AND HINGING POINTS PREVENTS UNHINGING OF SHELVES PREVENTS COLLAPSING OF SHELVES HOT-DIP GALVANIZED CONCRETE CURING SOLUTIONS. MADE IN GERMANY

5 The Quadrix system can be controlled conveniently from the outside via a touch panel. Spraying unit for the coating, which cures under UV light in the next station. The Quadrix system is specially designed for the independent control of temperature and relative humidity. The appearance and quality of the final products is improved by the separate and precise control of air circulation, temperature and humidity. According to the manufacturer, the advantages are a constant temperature of +/- 1 C, a constant relative humidity of +/- 3% and an air velocity under 1 m/sec. The system operates with a very high efficiency of 93%. The completely redesigned concept is based on a high air volume and low air speed inside the rack passages and results in an improved, consistent concrete surface. Constant climate in the large chamber The Gerwing concrete plant was quickly convinced that it had taken a correct and important step by investing in the Quadrix system. The optimised room climate prevents condensation in the complete chamber and constantly consistent results can be achieved on each production day of the year, irrespective of the outside temperatures. Thus, early strength has been increased, the colours are uniform, the surface quality has been improved and the cement requirement has been reduced. Extractor hoods prevent condensation in the production area A very important element of the Quadrix system are the extraction hoods, which are located above the production openings on the wet and dry side. After all, problems could be caused in the production area by warm, humid air escaping from the openings through which the fresh concrete products enter the chamber and the cured products leave it. The Wundersteins are also put to the acid test in the adjacent concrete laboratory. 82

6 The concrete products, packed and protected by film, are stored in a roofed-over area at Gerwing. The Kraft Curing extractor hoods solve this problem by drawing in the air with aluminium hoods and blowing it back into the curing chamber. In order to prevent condensation forming on the extractor hoods, they are electrically heated to a temperature of 40 C. Reliable prospects for innovative activities of mid-size enterprises The development of the Wunderstein was sponsored by the Zentrale Innovationsprogramm Mittelstand (ZIM) [Central Innovation Programme for Mid-size Enterprises]. The ZIM is a German nationwide programme of market-oriented technology sponsorship for mid-size enterprises. Sponsorship is given to research and development activities (R&D) that take place in Germany and are aimed at Concrete Wundersteins and coated concrete slabs in visual harmony.

7 Hardness test of conventional concrete paver (left) and Wunderstein: even stubborn dirt can simply be wiped off the Wunderstein, while the other stone still shows clear traces. innovative products, procedures or technical services as well as supplementary performances for their market introduction. The technology-neutral and industry-neutral sponsorship programme, which started in July 2008, is intended to lastingly strengthen the innovative force and competitiveness of the companies and thus to contribute to the growth of the companies in association with the creation and securing of jobs. The Wunderstein a licensed product too The Gerwing company developed the Wunderstein. Despite that, other concrete plants can also produce the Wunderstein as licensees. No sooner had Gerwing entered the market with this licence offer than the first licensee was found in the USA, which will also be producing the Wunderstein from now on. Gerwing accompanies the start of production at its licensees and advises them. Transferring knowledge to the licensee is one thing, but the processes all have to work. And Michael Gerwing has the know-how for that. In general he sees great potential for his product on the North American market. However, it is also expected that the Wunderstein won't just be produced by Gerwing in Europe in future. For its own production, Gerwing sees the Wunderstein as the product of the future that will replace the classic concrete products. This development is already becoming apparent in the concrete slab sector. Gerwing no longer offers uncoated concrete slabs. FURTHER INFORMATION Gerwing Steinwerke GmbH Industriestraße Holdorf, Germany T F info@gerwing.de Kraft Curing Systems GmbH Muehlenberg Lindern, Germany T F info@kraftcuring.com QAVERtec GmbH Lise-Meitner-Str Flensburg, Germany T F info@qavertec.com Watch a video about the new Wunderstein from Gerwing! Simply scan the QR-code with your Smartphone and you will be taken directly to the video. /cpi-tv/category/103/