Hybrid construction can offer a more sustainable way of building. To help drive this forward, Metsä Wood and its partners have designed a hybrid sandwich wall element combining concrete with Kerto® LVL (laminated veneer lumber).
The lighter weight of these hybrid sandwich wall elements proved to be a valuable benefit in the first construction project at Metsä Fibre’s Rauma sawmill. Skanska – the constructor of the new Rauma sawmill – has set up an ambitious goal for itself as it aims to be carbon neutral globally by 2045. This has led the company to provide low-carbon or carbon-neutral lifetime solutions to its customers.
“We are happy to try new, innovative things and partnerships, and the use of these new hybrid sandwich elements in the new Rauma sawmill is a great example of this kind of cooperation,” says Ilkka Romo, Director of the Productivity and Quality Unit at Skanska. “The use of hybrid elements reduces the amount of concrete, and the elements are also lighter than typical elements.”
Romo foresees that timber construction is set to increase and there is already now more demand appearing. The forms of timber construction and its impact on business and customer wishes are under review. “The hybrid sandwich element is a great start, and the Rauma sawmill project has provided us with useful first-hand information about their use in construction. It seems to fit well with our technical needs. Our co-operation with Metsä Wood and Metsä Fibre has started well thanks to the deep expertise of these two companies,” adds Romo.
The production of the new hybrid sandwich wall elements, which are used in the sawmill’s log sorting building, went as planned at the precast element manufacturer LipaBetoni’s factory. This is the first time the factory produced hybrid wall elements.
In their production, a Kerto LVL panel forms the load-bearing core. This is followed by an insulation layer and reinforced concrete facade.
“After overcoming the initial challenges, the production of the hybrid sandwich wall elements has been as easy as the production of concrete sandwich elements,” says Satu Lipsanen, CEO of Lipa-Betoni. “We have succeeded in this thanks to the close co-operation and extensive know-how of our partners.”
Both kinds of panels have identical connections in the bottom, and the seams of the hybrid sandwich elements have timber screws. After the assembly, the seams of the panels are finished and there is no need for seaming, concrete grinding or cleaning, as is the case with concrete sandwich panels.
“The assembly has been similar to the usual concrete sandwich elements. We were able to use a lighter crane in the assembly as the hybrid sandwich wall elements are lighter than traditional sandwich elements. Their lighter weight can bring savings in a large construction project,” says Petri Puputti, Construction Manager, Skanska.
The installation of panels for the building’s first floor – 100sq m – took just five hours. The sorting building will be ready by the end of 2021 and the sawmill is planned to be complete in 2022.
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