Building to Building to Building to Binder (Bn)

• Applicant: Professor Dr.-Ing. Karl-Christian Thienel
• Subject Area: Construction Material Sciences, Chemistry, Building Physics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 542053617

This research proposal aims to show the way to low-emission concrete production by using renewable lightweight aggregates and exploiting the high carbonation capacity of lightweight concretes. The primary objective is to develop renewable aggregates for lightweight concretes capable of absorbing CO2, while being fully recyclable and reusable in end-of-life scenarios. This proposal explores research areas related to reused lightweight aggregates with a special emphasis on their carbon sequestration potential. The project considers three main types of lightweight concrete as representatives to start the recycling strategy: structural lightweight concrete, lightweight aggregate concrete and infra-lightweight concrete. With a focus on the recycling process, this proposal seeks to identify the key material characteristics that enable the utilization of recycled materials as Recycled Lightweight Concrete Aggregates (RLCA) and Recycled Lightweight Concrete Powders (RLCP) in Recycled Lightweight Concrete (RLC). These characteristics encompass density, water absorption, particle strength, particle size distribution, particle shape, proportion of hardened cement paste and lightweight aggregates, as well as reactivity tests for RLCP as supplementary cementitious materials. Additionally, it involves evaluating CO2 absorption of the initial lightweight concretes, as well as of the recycled materials under natural and accelerated carbonation conditions. In the subsequent phases, this research proposal focuses on effectively integrating the recycled materials into RLC formulations. This process includes the development of reference recipes for different types of RLC and an assessment of RLC performance, while considering varying replacement levels of RLCA and/or RLCP. Furthermore, the long-term performance of RLCs is analyzed, taking into account factors such as elastic modulus, sustained loading and shrinkage. The objective of the proposed research project is to develop a closed-loop sustainability model taking into account the emission savings potential (Net-Zero) for the construction industry. It will demonstrate the feasibility of using 100% recycled materials and show how performance parameters evolve with each recycling loop. This research integrates innovative approaches and state-of-the-art materials. It aims to develop sustainable lightweight concretes that promote circular economy, protects the environment, and contributes to the reduction of CO2 emissions in the construction industry. As such, this project responds to the urgent global need to mitigate climate change and transition to more sustainable construction practices, making it a crucial step towards a green and sustainable future.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2436: Net-Zero Concrete