Bolted connections are one of the most common ways to connect precast structures on construction site, allowing time-saving installation process without a high amount of effort or manpower. They are also prominent solutions for enabling the dismount of connections due to reversibility, which means that bolted connections can be opened and tightened by similar means.
The number of current standards recognizing the dismount of structures is found very thin. The one notable standard setting the principles and guidelines for demountable connections is ISO 20887 International Standard – Sustainability in buildings and civil engineering works – Design for disassembly and adaptability – Principles, requirements and guidance.
In 2019, Peikko executed the first demountability tests with short precast columns and foundation blocks. These first-hand experiments showed that dismounting the connection between precast structures is easier than expected, and even a conventional bolted connection can be dismounted and reused without high demand of time or effort. This set a motivation for a larger scale of pilot project, which was executed in the end of 2021. In this pilot project, the whole precast concrete frame with DELTABEAM® Green composite beams was assembled, disassembled and yet reassembled.
To assess gained benefits from the dismount and reuse of structures, the demountable load-bearing frame was confronted against a reference frame, not meant for reuse. Economic and environmental impacts of different building components and required dismount processes were defined by calculating the cost (EUR) and carbon emission (kg CO2) parameters. The study showed how the economic and environmental costs of demountability can be compensated by enabling effective reuse.
It is concluded that bolted connections are in line with the principles of ISO 20887. The pilot project showed that the existing connections can allow the effective dismount and reuse of the precast structures. Enabling the dismount and reuse of the structures also provides clear economic and environmental benefits when compared to similar load-bearing frames without intended reuse.
Read the White Paper: Dismount and Reuse of Precast Concrete Structures
Jaakko Yrjölä
M.Sc.
Senior Manager,
Sustainability & Research
Peikko Group Corporation
