Towards cement and concrete as a carbon sink

Scope:

Background and scope:

Cement is the largest manufactured product in the world by mass. In 2022 humans produced 4,2 billion tons of it (about 626 kg per capita). Combined with water, sand and aggregates cement is the glue to form concrete. Aside from water, there is no material we use more than concrete. Contractors can combine concrete with steel reinforcement bars to mould and create the build environment in which we experience our lives. The industry is interrelated with other major sectors such as energy and steel. Its supply chains are vast, deeply complex, with increasing degrees of fragmentation going downstream. This complexity is also reflected in the many ways cement and concrete markets can be (sub-) segmented, for example by cement use (concrete, mortar, etc.), concrete use (reinforced, non-reinforced, ready-mix, precast products, etc.), end-use (residential, non-residential, infrastructural, energy, etc.) to name a few.

Cement and concrete are versatile, low-cost, abundant and relatively local. Modern societies are hard to imagine without these materials. Realistically, cement and concrete are here to stay. Then again, current mainstream cement and concrete technologies are also the source of 8% of our CO2 emissions (about 600 kg per capita), which are “embodied” in our buildings and infrastructures. Roughly 60% of these emissions are “chemical” released by converting limestone into clinker, and 40% of doing so at very high temperatures by burning fossil fuels. With EU (and global) commitments for rapid and radical emission reductions, it is necessary to pull all scientific, economic, and regulatory levers to reduce the environmental impacts of the cement and concrete sector.

One default pathway to decarbonize cement (and indeed a major element in the sector’s strategy to decarbonize to net-zero by 2050) is to capture and store CO2 of current production processes (CCS). Technologies for CCS are in development and expected to increase the cost of cement. To avoid additional costs of future emissions as much as possible, accelerated deep-tech innovations are needed to fully negate or even absorb emissions by the sector in future. The breakthrough innovations sought with this Pathfinder Challenge aim to be more cost effective than CCS. Moreover, this Pathfinder Challenge encourages breakthrough innovations that utilize CO2. Such innovations can play an important role in future CCUS economies, and trigger future revenue opportunities for the sector by offering negative emissions at scale. However, CCS/CCUS technologies that are unrelated to cement and concrete technologies are out of scope of this Pathfinder Challenge.

This Pathfinder Challenge seeks to support breakthrough innovations and (alternative) pathways for decarbonized and carbon-negative cement and concrete. Future pathways must meet some important conditions to be ultimately successful.

• The economical and abundant availability of feedstock at the place of production (cement) and consumption (concrete) is an important condition for implementing practically viable alternative cement chemistries, concrete mixtures and substitute materials.
• Most of the consumption growth of cement (and associated CO2 emissions) is expected in developing nations. Therefore, if innovative (deep-tech) solutions for cementitious materials are to be adopted on a significant scale (a condition for “disruptive innovation”) they shall (at least in potential) be low cost and used easily by people with minimal training and scientific knowledge.
• Ultimate success and technology adoption shall depend on meeting or exceeding the mechanical and operational performance levels of the incumbent mainstream cement and concrete technologies, which are also reflected in the various norms and standards.

Specific objectives:

This challenge is supporting the development of breakthrough technologies in one or more of the following domains:

(1) Advanced technologies that change the paradigm of prevailing binder technologies with alternative low-carbon compounds based on alternative feedstocks (e/g magnesia-based, (ultra-) mafic rocks), and curing processes (e/g carbonation curing), and the combination thereof. Widespread adoption of such radical new pathways will also need breakthrough innovations in energy efficient industrial production processes. Such engineered carbon mineralisation pathways (e/g MOMS) can in principle utilize and store large amounts of CO2 with high permanence and (CCUS) value in the final mortar and (reinforced) concrete applications. As the alternative feedstocks often formed the host rocks for valuable ores, some mine waste could contain accessible, abundant, and useful raw materials.

(2) Advanced technologies for a more efficient use of clinker in cement (reducing its clinker fraction), and of cement in concrete compositions (binder efficiency).

• For cement, radical innovations are sought that further extend the use of supplementary cementitious materials (SCMs), and that give access to novel, abundantly available alternative sources of reactive SCMs compared to the prevailing SCM materials that have limited (or even declining) availability.
• For concrete, the amount of binder used to produce concretes of a given strength can vary considerably (e/g depending on use case and geographical location). This points to substantial CO2 mitigation potential with innovations that solve for a consistently more efficient use of cement, for example. through innovations that optimize and control particle size distribution (e/g more sophisticated grinding processes) in combination with compatible admixtures, and technologies that support industrialization to reduce variability of binder intensity and reduce waste.

Novel reinforcement technologies may further improve efficient use of cement in reinforced concrete (e/g consumption driven by concerns about steel corrosion), and may be necessary for novel pathways for cement and concrete technologies that are not compatible with steel reinforcement.

• Novel pathways for compatible and equally performing “synthetic aggregates” may offer additional potential for CCUS at the concrete-mix level.

(3) Advanced technologies that lower or negate the need for burning fossil fuels to avoid the associated CO2 emissions. For example, novel breakthrough process innovations to manufacture decarbonized lime (e/g at low process temperatures, by non-thermal processes, electrified processes).

(4) Enabling technologies in support of (1), (2) and (3) based on technologies for computational material science or data-driven science (including AI and ML). There is a need for breakthrough simulation and prediction technologies that enhance the understanding of the characteristics and interactions of raw materials, hydration processes and microstructural development of cementitious materials. If generalizable technologies can be adapted to a wide variety and variation of real-world raw materials without the need for extensive local empirical testing, this would greatly enhance and accelerate development cycles, knowledge acquisition, discovery, and implementation.

Expected outcomes and impacts:

Project results must clearly demonstrate validation in laboratory environment (TRL4) of the breakthrough technology.

The portfolio of projects selected under this Pathfinder Challenge is expected to cover the four (4) domains mentioned in the previous section. The collaboration between the selected projects is expected to be mutually beneficial and contribute to a further reduction of carbon emissions of cement and concrete. For example, the projects selected under 1, 2 and 3 will be required to closely collaborate with the project selected under 4, so that this project can provide additional guidance to the projects on plausible pathways.

In addition, projects are required to develop common metrics and terminology to compare project results. The results of each project shall include a rough order of magnitude (ROM) estimation of the potential impact the breakthrough technology can have on emission reductions. A portfolio activity that results in quantitatively stating the decarbonization potential of all portfolio projects combined is encouraged.

Also, portfolio activities to develop techno-economic views on the future implementation, adoption, and scaling potential of the various technologies in realistic real-world conditions, coupled with a view on an entrepreneurial path towards future commercialisation are strongly encouraged. Realistic expectations of operational conditions in those markets where future growth is expected most is critical for the adoption of innovative technologies at scale. For example, feed stocks required for some novel pathways may be found at different locations than existing quarries and cement plants. This requires a strategic rethinking of the cement and concrete value chains and distribution channels in target markets. Also, novel pathways utilizing CO2 for curing will require a stream of (likely) purified CO2, which triggers additional supply chain considerations. Other novel pathways may adopt to existing cement and concrete value chains and distribution channels as an innovation strategy for fast scaling and wide market adoption.

Any innovation that offers a reduction of CO2 emissions shall still enable, meet, or exceed the performance and workability criteria of the incumbent products it enhances or substitutes by the time of market adoption, as referenced by various industry norms and standards. It is expected that the collaboration between the portfolio projects will positively contribute to the understanding of this topic.

In the long run, it is expected that project results will form the basis for the development of novel cement and concrete products, production processes, and other solutions that impact the sector in its efforts to decarbonize and even absorb CO2 in step with the ambitions of the European Green Deal.

The portfolio of supported projects shall also contribute to medium to long-term impacts such as increasing EU technological leadership and reducing EU dependency on critical raw materials supply.