CIRCLE (Concrete Innovation for Recycled Content and Low Environmental impact)

Tackling challenges in upscaling recycled aggregate concrete
Concrete bridge

CIRCLE (Concrete Innovation for Recycled Content and Low Environmental impact)

Tackling challenges in upscaling recycled aggregate concrete
Title: CIRCLE (Concrete Innovation for Recycled Content and Low Environmental impact)
Dates: 2025-2029
Project partners: Instituto Superior Técnico, Portugal (lead), University of Plymouth, UK, Liverpool John Moores University, UK, Cy Cergy Paris Université, France, Ho Chi Minh City University of Technology, Vietnam, Universiti Malaysia Perlis, Malaysia, Walailak University, Thailand, Universitas Brawijaya, Indonesia, Kookmin University, South Korea, Shenzhen University, China 
University of Plymouth PI: Dr Boksun Kim
 
The overarching goal of the CIRCLE project is to establish an international network of 10 organisations dedicated to addressing the challenges associated with the wider adoption of recycled aggregate concrete (RAC). 
 

Intercontinental secondments planned within CIRCLE will provide a framework for collaborative research, knowledge exchange, training and networking. These activities will benefit staff at all career stages across the participating institutions, as well as PhD students, strengthening research capacity and fostering long-term international collaboration.



Bringing together European and Asian countries, CIRCLE addresses a shared and pressing need to develop concrete infrastructure while reducing its environmental footprint. Given concrete's global dominance as a construction material, the widespread adoption of RAC offers substantial environmental, economic, and social benefits. Growing recognition of this potential among public authorities and industry stakeholders has already prompted initial efforts in some consortium countries to develop relevant regulations and frameworks. CIRCLE is therefore particularly timely and can provide evidence-based recommendations, technical guidance, and policy-relevant insights to support the development of appropriate standards and guidelines.
By accelerating research collaboration, facilitating knowledge transfer and supporting the responsible uptake of RAC, CIRCLE will contribute to more sustainable construction practices and the transition towards a circular economy, in alignment with European policy priorities and the United Nations Sustainable Development Goals.
 

Project objectives

  • To enhance the quality of RAC, in terms of strength and long-term durability, by developing innovative self-healing and/or bio-based solutions and exploring the effect of forced carbonation of RA and RAC.
  • To determine the influence of high-quality RA and crushed concrete powder (CP) on the strength and durability performance of RAC, using advanced laboratory testing methods, and to develop theoretical models that predict the concrete properties based on its composition.

  • To quantify the social, economic and environmental impacts of the use of quality-controlled RA and RAC in the construction industry and identify hotspots, by using state-of-the-art life cycle assessment (LCA) tools.
  • To evaluate case study applications of RAC and provide knowledge based on such aspects as source/quality control of the RA used, mix design of the RAC used, expected performance/design adaptations of RAC, types of final application and resulting impacts.

 
Perspective view of empty concrete floor with cement structure and wooden wall building exterior. 3d rendering. SDG9
Concrete is the world’s second most widely used material after water and is fundamental to modern construction. It consists of three main constituents: cement, water and aggregates. 
Aggregates account for about 60–70% of concrete’s total volume, making their extraction and use a major source of environmental pressure. Although recycled aggregates (RA) are technically feasible for use in concrete production, their use remains limited. Wider adoption of RA could significantly reduce construction and demolition waste sent to landfill, conserve natural resources, and retain the value and embodied energy of materials within the construction cycle.

 
The CIRCLE consortium brings together an interdisciplinary team of internationally recognised researchers with complementary expertise in recycled aggregate concrete (RAC). They will integrate their collective knowledge through a carefully structured programme of activities designed to achieve the project’s overarching objectives. 
These activities will include advancing knowledge of bio-based self-healing and carbonation in RAC; developing high-performance RAC; optimising RA and RAC quality; assessing their environmental, economic, and social implications through multi-criteria life cycle assessment; and validating RAC performance in full-scale, real-world applications. 
This integrated approach will bridge the gap between research and practical implementation, supporting wider RAC adoption and accelerating the transition to more sustainable, circular construction practices.

Kölnbrein Dam, concrete dam with skywalk platform in an Austrian valley Malta.

Centre for DecarbOnisation, Resilience and Energy Systems 

We bring together leading researchers from across the University of Plymouth to develop innovative solutions to the national and global challenges of decarbonising energy systems, strengthening resilience to climate change and security risks, and supporting sustainable economic growth. 
Centre for Decarbonisation and Offshore Renewable Energy