For all their companies, Rohrdorfer Group decides in favor of efficient and environmentally sound plant equipment, a customer-oriented product range and thorough quality control, thus complying with the objectives that the founder, Georg Wiesböck, once initiated as driving force: uncompromising production of high-quality and contemporary building materials. In addition to cement, the group is manufacturing ready-mixed concrete, concrete products and precast concrete elements as well as extracting sand and gravel at more and 40 locations in Germany, Austria, Hungary and Italy.
At present, about 1,000 people, employed in legally independent companies of the Rohrdorfer Group, satisfy the construction demand in the respective regions.
Modernization within three months
Betonwerk Linden, being one of the companies, has been manufacturing paving blocks, slabs, masonry systems and retaining wall systems at several locations since 1966. The product range is complemented by steps and bollards, palisades, border stones and products for civil engineering, such as curbstones and perimeter stones. Thus, the company offers sophisticated and efficient product solutions in all fields of garden, landscape and urban design as well as pipes, manholes, wastewater treatment plants for the sector of classical civil engineering and products for the environmental engineering sector. Taking the Berglern production site situated close to the Bavarian state capital of Munich as an example, it becomes quite obvious that, for achieving these targets, the focus above all is on modern production lines with largely automated manufacturing process as well as permanent quality monitoring combined with a perfectly coordinated transportation and supplier system. The company, moreover, attaches great importance to environmental protection and resource efficiency: The main components, such as cement and aggregates are delivered by the Rohrdofer Group itself or local suppliers so as to avoid transports over long distances. Some of the sand and gravel pits, that had been in operation since the early 1960 s, were already closed down, being renaturalized in a sustainable way as new lakes.
When a new production hall was built at the end of 2013, owing to the strong demand, the production line in Berglern was up for comprehensive modernization, which was successfully completed in just three months. In the past, the old production building was primarily used for manhole units and floor elements, however, a wide range of concrete products has been manufactured at the same site since 2008. Meanwhile, concrete paving blocks are manufactured in a three-shift operation, among others, for major customers, such as the city of Munich or the Franz Josef Strauß airport. The state-of-the-art equipment consists of a batching and mixing plant of Gasus Dosier- und Fördertechnik GmbH suitable for the slab production line, supplied by TopWerk-Unternehmen SR Schindler, in combination to the existing block making machine of Masa.
New slab production line and existing block making machine
The scope of supply on the part of Gasus Dosier- und Fördertechnik included an aggregate feeding and storage system with a conveying capacity of 220 m³/h associated with 13 bins of 60 m³ each for face-mix aggregates and 4 bins of 120 m³ each for base-mix aggregates. An on-site steep belt conveyor carries the aggregates to a Gasus shuttle conveyor for silo feeding. This shuttle conveyor, mounted on a carriage, is turnable and moveable and transfers the aggregates to the individual bins. Gravimetric batching of the aggregate is done by means of dosing belts transferring to weighing and shuttle conveyors of 4000/1000 kg (each of Gasus) to the two mixing plants for the production of paving blocks and slabs. Concrete is fed to the slab machine by means of belt conveyors (base mix) or mobile hopper (face mix), including weighing equipment for concrete requirement of/dosing in the slab machine.
The mixing equipment for the existing block making machine with an overall capacity of 350 m³/day consists of the mixers Eirich RV 12 for the face mix and Teka PGM 2250 for the base mix, furnished with an elevator each. A new Eirich RV 12 (face mix) and an existing, reconditioned Teka PGM 1500 (base mix) carry out their duty at the new slab production line, with a concrete output amounting to about 250 m³/day.
Although several more suppliers are involved in the production process, such as Bikotronic for the control system, Inter Minerals, Omya, Harold Scholz, Lanxess and Remei for the concrete aggregates and additions as well as release agent, no difficulties occurred in any project stage, that are worth mentioning.
Satisfied statements of all project parties
All those involved in the project thus gave positive comments. Herbert Ehard, General Manager of Gasus, right on site stated obviously satisfied: “Beginning with the contract award at the end of May 2013 to the start of the assembly work mid October to the commissioning in February 2014, the project run quite fast and smooth, thanks to the good cooperation of all parties involved.” Dirk Heuer, Technical Sales Manager at Maschinenfabrik Gustave Eirich, was also pleased: “Our mixer of type RV 12 ideally fitted in both the new equipment for the slab production and in the existing block making machine.”
Gerhard Obermaier, authorized representative and factory group manager west at Betonwerk Linden, added: “Apart from the new installation, the connection to the already operating production lines, in particular, was a special challenge, which was excellently mastered by the supplier of batching systems, Gasus, as well as by the supplier of mixing plants, Eirich.”