Growing Infrastructural Markets

Construction of a New Pipe and Manhole Ring Production Facility

 Midt-Norsk Betong has its headquarters in Verdal, close to Trondheim, Norway. For slightly over a year, a brand-new factory has been in operation only a few meters away from the old site. The plant produces precast units for civil engineering and supplies the central part of Norway, i.e. the region around Trondheim. The company management decided to “put all eggs in one basket” and to invest in the growing infrastructural market.

The history of the business began in 1922 when its founders, Messrs. Albertsen and Dillan, started to manufacture concrete roofing tiles. The first machine for this purpose, an egg layer, was purchased in 1927. This machine had an output of 450 roofing tiles or concrete slabs per day. After the end of the Second World War, the concrete plant moved into an old, vacated shed erected during the war. The company remained on this site for many years and constructed a new factory building in 1961. The production of pipes and manhole rings was launched in 1954. A new transport system was installed to complement the product range in 1963. This was a ground-breaking investment because a completely new control unit was installed that offered a standard that was very advanced at the time. In the 1970s, the business invested in a pipe machine with a hydraulic press for the first time.

In 1979, an interest in the factory was sold to Norcem (HeidelbergCement). Ever since, the company has been operating as part of a group. In 1991, the precast division was sold to the workforce. The ready-mix arm was sold to Unicon A/S in 1994.  

Midt-Norsk Betong had to make a crucial decision amidst the global economic and financial crisis: either to invest in new equipment and machinery or to use the existing plant layout and technology to manufacture the product range. Even a plant closure had to be considered at some point in the process. The goal was identified very quickly: according to the company’s view, concrete products do have a promising future in Norway. Yet, in these difficult times, the raising of the required funds took more time and negotiation effort than anticipated. At the end of this process, however, the company was able to make a big step towards technological progress and to build a brand-new factory. Unfortunately, the old site did not provide the necessary space. Only a few meters away, however, a plot of land was found in the Ørin industrial estate. The new factory buildings were inaugurated on 19 November 2009.  

Today, the company employs 13 people. Almost all of them have undergone professional or further training in the field of concrete technology.  


Danish production line chosen once again

The new production line is a VIHY® Multicast SC 250 system that was designed and supplied by HawkeyePedershaab, the equipment manufacturer. Due to lack of space, the usual clockwise cycle (viewed from the concrete skip) could not be installed at the Verdal plant.

 The following layout was chosen at Midt-Norsk Betong Verdal: from the mixer level (Skako mixer with a capacity of 1.5 m³), a belt conveyor transports the low-slump concrete to the feed hopper of the Vihy Multicast line. Plant manager Roar Olsen takes pride in that his factory includes the most advanced mixing unit in Northern Norway, according to him. The feed hopper also has a capacity of approx. 1.5 m³ and works as an intermediate container to feed the concrete as and when required for the production of the respective precast unit. For this purpose, the concrete is again transported via a conveyor mounted to a slewing metal frame.

 The amount of concrete and the mix design for the precast unit are specified via the central control panel for the manhole ring machine and the mixing unit. Six mix designs have been stored in this factory.

 The control unit invokes the stored mix design and the production parameters for the pouring of the concrete for the manhole ring or cone. The slewing conveyor with the concrete mix travels to the manhole ring mold and automatically positions itself in the central area above the mold. Concrete is discharged into the mold via a rotary table. This short rotary shuttle conveyor places the concrete between the mold walls. Depending on the type and height of the product, concrete may also be poured layer by layer. Once the mold has been filled with concrete completely, the compacting plate suspended from the frame is put onto the mold. This plate is pressed onto the precast unit applying hydraulic force. A profiled steel ring is attached to the bottom of the compacting plate. This steel ring is also operated hydraulically and can perform tilting and vibration movements, which are necessary to accurately shape spigot ends and sockets.

This contact pressure is applied to the precast unit from above, and the unit is compacted completely. In the Vihy Multicast line, compaction is performed by table vibration. The related parameters are also stored on a product-specific basis in the production line control unit and are applied automatically during the manufacturing process.

 Once the unit has been compacted, both steel mold and precast unit can be lifted from the inner core. A mobile gantry crane and a suspended cross-beam lift the mold with the precast element and transport it to the separate curing area in the factory building, where the manhole ring is placed on the bottom pallet. The mold is opened by loosening the lateral brackets, and lifted from the precast unit. Support rings are placed on the manholes to stabilize their shape.

 The empty mold is fed back into the machine and placed on a new bottom pallet. The required reinforcement with spacers is fastened in the steel mold. When the bottom pallet and mold have been connected to each other, the steel mold is clamped to the table of the Multicast line. A new production cycle starts.

 The concrete is currently mixed with sea sand (0-8 mm) and as-raised gravel (8-14 mm). It should be noted, however, that the composition of aggregates has been modified recently, which results in a significantly better quality of the concrete surface. Two cement grades are currently available for concrete mixing. The central control unit for the mixer is located in the company’s offices. Only the mix designs and technical parameters can be invoked from the factory building. The plant manager is the only person able to intervene in the concrete technology settings from his computer.


Strategy and company philosophy

The company is also a member of the Basal Group and manufactures the related products (see BFT INTERNATIONAL 11/2009). Basal A/S is a supraregional entity covering the whole of Norway to sell all products in the field of water supply and sewage whilst applying a uniform quality standard. As a group member, MN Betong also benefits from the synergies arising from this cooperation. For instance, the usual approach is to purchase products from other group members that the company cannot manufacture at its own factory, or, conversely, to sell those precast products that are not manufactured by other factories. A clear advantage of this structure is the focus on one’s own core expertise whilst securing a high quality standard because of the restricted product range.

 Products manufactured at the Verdal plant include not only various manhole rings and cones but also Uniklikk® products, sand traps, duct covers and the Trønderblok range. The latter block is a product specific to the Trondheim region: rectangular concrete blocks weighing approx. 250 kg that are used to stabilize road embankments and slopes. The Optikum manhole base produced at the factory is fitted with a drain insert made of yellow plastic. This manhole base is also one of the significant Basal products.

 The manhole units produced on the Vihy Multicast line may be 1,000, 1,500 or 1,600 mm in diameter and come in different heights (maximum height 1,500 mm). Pipes in diameters of 600 mm and heights of up to 2,250 mm may also be produced.

 In retrospect, the members of the management team of the precast plant emphasize the good cooperation with HawkeyePedershaab – the first contact had been established already several decades ago. Staff were trained by the Danish engineering company to get familiar with the new table vibration technology as core vibration had been used previously to manufacture the precast units. Yet right from the beginning, this technical modification did not pose any problems with regard to the production process or product quality. The production system is very stable; it can be turned off in the evening, and production continues on the next day using the parameters of the previous day.

 In conclusion, Roar Olsen stresses that “our new production line is easy to handle and particularly easy to operate. As and when required, we also get additional support from HawkeyePedershaab via a dedicated Internet connection.”


A forward-looking approach

The company is currently planning to install a second system in the factory building. Negotiations with the Danish/US engineering company are currently underway. The second basement needed for this system was part of the project brief and has already been built.

 Company management are also considering the launch of new products and integrated solutions. “Today, the most important thing is to respond flexibly to market needs,” says Roar Olsen. “The pipe diameters requested by municipal utilities are constantly changing. Both demography and infrastructure will change. And here in Norway, we must be able to come up with sound and durable concrete solutions to cater to our climatic conditions.” A strong customer focus is also very important in a country like Norway with its small number of inhabitants. There are many arguments in favor of a regional market structure given the high transport costs of heavyweight precast units.

 In Norway, the market for precast units for civil engineering is growing and will continue to do so according to current estimates. Yet the product range will grow at the same time. Norway can tackle this “issue” effectively using the Basal cooperation model: companies in the group manufacture only a certain part of the required product range and purchase the remaining items from within the group. 


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