Understanding what is already inside existing buildings is an essential step towards making construction more circular.

At the Jolastokieta pilot site in San Sebastián, Spain, SUM4Re partner Moyua is carrying out activities focused on the characterisation of existing concrete and the validation of non-destructive inspection technologies. The work aims to improve the reliability of information about existing construction elements and support better decisions before demolition.

Characterising existing concrete

As part of the ongoing activities, concrete samples have been collected from different structural elements at the pilot site, including columns and foundation-related elements.

The samples have been sent to TECNALIA for further testing and characterisation. This provides representative material from the pilot site that can be used for subsequent SUM4Re activities and helps build a better understanding of the existing construction elements.

At the same time, EAGLE’s on-site scanning technology is being evaluated through direct comparison with physical samples extracted from the same areas.

Comparing scans with physical evidence

One of the key aspects of this work is the comparison between what the non-destructive technology detects and what can subsequently be confirmed through physical inspection.

Although most of the extracted concrete cores did not intersect reinforcing bars, the comparisons have already provided relevant information for validating the sensing technology.

In one representative case, the scan indicated the presence of a concealed element at an approximate depth of 17 cm. The subsequent extraction and inspection of the concrete core showed good consistency with the scan results.

This type of direct comparison provides valuable ground-truth information, helping the project assess both the performance and the practical limitations of the technologies being developed and tested within SUM4Re.

Why does this matter for circular construction?

Before a building is renovated or demolished, having reliable information about its existing materials and structural elements can make a significant difference.

Better material information can help stakeholders:

• Identify existing construction elements more reliably
• Improve pre-demolition assessment
• Make better-informed decisions about materials
• Identify opportunities for reuse and recovery
• Support more effective recycling
• Reduce uncertainty when planning future interventions

For circular construction, knowing what materials are present, where they are located and what condition they are in is an important foundation for deciding what can be retained, reused, recovered or recycled.

From inspection to better decisions

The activities at Jolastokieta demonstrate how non-destructive sensing, physical validation and material characterisation can work together.

Rather than relying solely on assumptions about an existing building, combining digital inspection technologies with physical evidence can provide a more reliable picture of what is actually there.

For SUM4Re, this contributes to the wider objective of improving the information available about existing buildings and materials – supporting the transition towards more informed and circular construction practices.

The work at the Spanish pilot is therefore another step towards connecting building data, material knowledge and practical decision-making to unlock the potential of existing resources.