Information für die Wissenschaft Nr. 49 | 7. Juni 2023

Priority Programme “Net-Zero Concrete” (SPP 2436)

In March 2023, the Senate of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) established the Priority Programme “Net-Zero Concrete” (SPP 2436). The Programme is designed to run for six years. The present call invites proposals for the first three-year funding period.

Challenge

The production of concrete is responsible for approximately 7 percent of the global CO2 emissions. Hence, there is an urgent need to significantly cut back on CO2 emissions and to work on scientifically driven solutions for CO2 neutral (Net-Zero) concrete. For this, all common industrial procedures for cement and concrete production should be challenged from a materials perspective to significantly reduce its CO2 footprint, which are i.e. clinker production, cement composition, aggregate production, and carbon capture and utilisation.

Objectives and Scope of the Programme

Within this SPP, novel research pathways towards a climate neutral concrete will be pursued and explored. To achieve this, a multidisciplinary research approach, covering cement chemistry, concrete technology and related scientific areas such as physical chemistry (reaction thermodynamics and kinetics) and physics of materials, but also reusability and adaptability of resources and production procedures, is envisioned.

The proposed Priority Programme addresses the following main objective: pursuing a net-zero concrete based on alternative binders, renewable aggregates and carbonation strategies. The following three sub-objectives are considered to achieve this:

Experimental and numerical research on alternative binders and novel clinker raw materials in terms of composition and reactivity of the individual phases and their CO2 interactions.
Development of waste-based and/or renewable aggregate systems that have the potential to absorb CO2 and will be fully recyclable and/or reusable in an end-of-life scenario.
Development of advanced concrete carbonation strategies to maximize CO2 uptake in concrete production as well as during and after service life.

Whenever exploring possible cutting-edge solutions for CO2 reductions, these components can be considered individually and/or as cumulative combinations, leading to the following three complementary research modules within the SPP.

Module 1: Alternative and Carbon Neutral Binders

Alternative binder concepts based on alternative clinker materials, clinker-free or (ultra)-low clinker concepts either based on traditional materials or waste-based and/or CO2 binding replacements require a full understanding of the hardening process of inorganic binders, which fundamentally relies on the microstructural development, and chemical reactivity of its components. Both the initial production of clinkers and binder materials as well as their later use are determined by the thermodynamic potential and kinetic rates of the main reaction mechanisms. The hydration and/or polycondensation reaction during the application of binder materials is characterised by an initial dissolution of solid polymineral and/or amorphous particles in highly concentrated, typically highly alkaline and/or ionic super-saturated water-based suspensions. The dissolution reaction is succeeded by precipitation and/or nucleation and growth of reaction products, where particle-water interfaces, diffusion and availability of reactants in partly water saturated porous matrix will play a major role on overall reaction kinetics. Reaction kinetics, however, are key to allow for a wider use of composite binders, which currently still show significantly reduced early strength compared to plain Portland cements.

Module 2: Construction Demolition Waste and Renewable Aggregates

Concrete as such is made of a complex composition of mineral binder phases, aggregates and various additions that are optimised and intensively mixed together, with the aim to achieve a free form construction material that is capable of withstanding large compressive loads, with an excellent durability for nearly its entire service life. One of the major challenges is to change this durable construction material into a recyclable, renewable, and even more important, separable material that is circular with a least impact on the environment. Currently, most employed aggregates are “classical” river- or rock-based materials. These are sieved or crushed to the right size distribution that complies with an optimised packing density. Thereby, a least amount of cement paste is necessary to “glue” all components together to finally receive a concrete. New aggregate systems should be disclosed that enable a sound compliance with the environmental requirements, and which are carbon neutral and fully recyclable.

Module 3: Concrete Carbon Capture and Long-Term Carbon Sink

The utilisation of CO2 in concrete and its components is currently performed by converting CO2 from the gaseous state into solids (carbonates), commonly referred to as mineral carbonation. In order for CO2 to be bound in solids as carbonate, two essential components are needed: a) a supply of cations as binding partners to form a solid carbonate mineral and b) a supply of alkalinity that enables fast conversion of CO2 into carbonate ions. Most commonly calcium carbonate (CaCO3) is formed where calcium acts as cation. Alternatively, magnesia rich systems also show potential for CO2 curing due to the formation of hydroxymagnesites and other magnesium-carbonate hydrates such as nesquehonite, etc. The other typical elements present in mineral construction materials (such as Si and Al) are then combined into an A-S-gel during carbonation. While CO2 utilisation via mineral carbonation has gained considerable attention over the last years, an interdisciplinary research strategy is urgently needed to elucidate its full potential for achieving a net-zero concrete.

For more specific information on the Priority Programme, please visit the Programme’s website (see link below), which is open to all interested scientists. The website will also launch various initiatives for applicants to enhance the degree of coherence among project themes and to facilitate networking amongst potential project partners. Depending on their scientific background, potential applicants have the opportunity to discuss their possible contribution to achieving the overall goals of the SPP.

In the first funding period of the Priority Programme “Net Zero Concrete”, single PI projects are encouraged. Collaborative projects of maximum two PIs are meant for multiscale or cross disciplinary approaches whenever the synergetic benefits among the research topics are convincingly addressed. Reference materials will be provided by the central project to enable a comparison of the CO2 reductions of the individual projects. The individual and/or cumulative CO2 reductions achieved by each individual research project will be actively monitored based on the quantification of the main relevant performance parameters such as binder carbon intensity and clinker replacement ratio, CO2 uptake potential in various life-cycle stages, concrete carbon intensity, etc. An LCA-based approach will be carried out by the central project along the full duration of the SPP, while results will be presented and discussed during the various SPP events.

For the first funding period of this Priority Programme, the following information should be considered in the project proposals:

Research proposals should address at least one of the three above-described modules with emphasis on low-carbon mineral construction materials and reflecting research fields such as:

Alternative raw materials, low-carbon binder concepts, CO2 binding aggregates
CO2 binding mechanisms and/or its uptake potential
Thermodynamic and/or kinetic approaches for reaction mechanisms
Mechanisms for the development of physical-chemical properties
Materials’ microstructure-property relations.

Topics not considered in the first funding period of this Priority Programme are:

Large scale manufacturing approaches, e.g., clinker burning technologies, additive manufacturing, carbon capture technologies, etc.
Conventional aggregates and earth-based materials
Carbonation as a deterioration mechanism
Structural engineering and/or design optimisations
Steel or alternative reinforcement systems.

Proposals must be written in English and submitted to the DFG by 30 October 2023. In order to achieve maximum diversity, it is expected that each principal investigator (PI) is involved only in one proposal (obligatory). Please note that proposals can only be submitted via elan, the DFG’s electronic proposal processing system. To enter a new project within the existing Priority Programme, go to Proposal Submission – New Project/Draft Proposal – Priority Programmes and select “SPP 2436” from the current list of calls.

In preparing your proposal, please review the programme guidelines (DFG form 50.05, section B) and follow the proposal preparation instructions (DFG form 54.01). These forms can either be downloaded from our website or accessed through the elan portal.

Applicants must be registered in elan prior to submitting a proposal to the DFG. If you have not yet registered, please note that you must do so by 21 October 2023 to submit a proposal under this call; registration requests received after this time cannot be considered. You will normally receive confirmation of your registration by the next working day. Note that you will be asked to select the appropriate Priority Programme call during both the registration and the proposal process.

Further Information

More information on the Priority Programme is available under:

www.wib.tu-darmstadt.de

The elan system can be accessed at:

https://elan.dfg.de/en

DFG forms 50.05 and 54.01 can be downloaded at:

For scientific enquiries, please contact the Priority Programme coordinator:

Professor Dr. ir. Eduardus Koenders
Technische Universität DarmstadtInstitut für Werkstoffe im Bauwesen
Franziska-Braun-Str. 3, 64287 Darmstadt
phone +49 6151 16-22210

Questions on the DFG proposal process can be directed to:
Programme contact: