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WO-2026093651-A1 - CO 2 SEQUESTERED AGGREGATE AND A PRODUCTION METHOD THEREOF

WO2026093651A1WO 2026093651 A1WO2026093651 A1WO 2026093651A1WO-2026093651-A1

Abstract

According to an example aspect of the present invention, there is provided an aggregate and a method of producing the same, as well as uses thereof. The aggregate comprises a plastic soil, a carbonaceous material and a binder, and is produced by forming an aggregate mixture and subjecting such mixture to carbon dioxide curing.

Inventors

  • BORDOLOI, Sanandam
  • HANAFI, Mohamad

Assignees

  • AALTO UNIVERSITY FOUNDATION SR

Dates

Publication Date
20260507
Application Date
20251029
Priority Date
20241029

Claims (17)

  1. 1. A modified aggregate comprising a plastic soil, a carbonaceous material and a binder.
  2. 2. The aggregate according to claim 1, wherein the amount of the carbonaceous material is in the range of 1 to 30 wt.%, preferably 2 to 25 wt.% or 10 to 20 wt.%, calculated from the dry weight of the modified aggregate.
  3. 3. The aggregate according to claim 1 or 2, wherein the amount of the binder is in the range of 5 to 40 wt.%, preferably in the range of 10 to 30 wt.%, such as in the range of 15 to 25 wt.% calculated from the dry weight of the modified aggregate.
  4. 4. The method according to any of the preceding claims, wherein the plastic soil is clay, in particular waste clay, such as soft waste clay.
  5. 5. The aggregate according to any of the preceding claims, wherein the binder is an inorganic binder, such as cement.
  6. 6. The method according to any of the preceding claims, wherein the binder has a calcium oxide content of at least 60 wt.%, calculated from the total weight of the binder.
  7. 7. The aggregate according to any of the preceding claims, wherein the carbonaceous material has a carbon content of at least 50 wt.%, preferably at least 60 wt.%, calculated from the weight of the carbonaceous material.
  8. 8. The aggregate according to any of the preceding claims, wherein the carbonaceous material has a surface are of at least 80 m 2 /g, preferably at least 90 m 2 /g, such as 95 m 2 /g, more preferably at least 100 m 2 /g, determined by BET analysis.
  9. 9. The aggregate according to any of the preceding claims, wherein the carbonaceous material is biochar.
  10. 10. The aggregate according to any of the preceding claims, wherein the aggregate comprises: 60 to 90 wt.% of plastic soil, 10 to 20 wt.% of carbonaceous material, and 10 to 30 wt.% of binder, calculated from the dry weight of the aggregate.
  11. 11. The aggregate according to any of the preceding claims, wherein the aggregate is cured aggregate.
  12. 12. The aggregate according to any of the preceding claims, wherein the aggregate has a calcium carbonate content of at least 5 wt.%, preferably at least 6 wt.%, more preferably at least 7 wt.%, calculate from the dry weight of the modified aggregate.
  13. 13. A method of producing a modified aggregate, the method comprising the steps of: providing a mixture of a plastic soil, a carbonaceous material and a binder, subjecting the mixture to an aggregate pelletization to provide an aggregate, and subjecting the aggregate to a carbon dioxide curing to provide a modified aggregate.
  14. 14. The method according to claim 13, wherein the mixture is obtained by mixing together clay, biochar and inorganic binder, such as cement.
  15. 15. The method according to claim 13 or 14, wherein the curing is accelerated CO2 curing (ACC).
  16. 16. The method according to any of claims 13 to 15, wherein the aggregate mixture is subjected to hydration treatment prior to the curing step, wherein the water content of the aggregate after the hydration is preferably 20 to 40 wt.%, such as 30 wt.%, calculated from the total weight of the aggregate.
  17. 17. Use of the aggregate according to any of claim 1 to 12 as a backfill material or in insulation materials, cementitious composites or pedestrian block asphalt.

Description

CO2 SEQUESTERED AGGREGATE AND A PRODUCTION METHOD THEREOF Background of the Invention Field of the Invention The present invention concerns an aggregate and a method of producing the same. In particular, the present invention concerns a modified aggregate comprising a plastic soil, a carbonaceous material and a binder, and uses thereof. The method is based on carbon dioxide curing of an aggregate comprising said components. Thus, according to one aspect the field of the invention is working and improving the weak soil conditions by adding into a plastic soil a carbonaceous material, in particular biochar (a carbon negative by-product from the pyrolysis process), moderate amounts of a binder (cement/lime/fly ash), and sequestered CO2 gas to develop robust lightweight aggregates that can be used as fill materials and for developing low-carbon masonry cementitious blocks. Description of Related Art Weak soft sensitive clay constituting most of the Finnish geological landscape is often landfilled or stabilized using cement before conducting any construction activities. The Finnish government mandates the construction sector to reduce the CO2 emissions from the industry by practicing circular economy strategies of available waste resources. The addition of Portland cement (PC) as a binder material in cementitious composites contributes to the third largest global emitter of CO2 (0.8-1-ton CO2 per ton of concrete). The European Union and Finnish parliament target to achieve net-zero CO2 emissions by 2050. Apart from cement usage in the construction sector, another source of CO2 emission in Finland is in the transportation and landfilling of waste soft sensitive clay. This waste clay, along with mined earthworks, accounts for 86 million tons of annual unused inorganic waste as per the latest governmental report on national economy material flows. Finnish soft clays are geologically widespread and are notoriously known to be a weak stratum (disturbed compressive strength < 20 kPa) for infrastructure development and need to be either strengthened by cement stabilization or landfilled after excavation. In practice, the excavated soft clay in shallow depths is backfilled as waste by either mined or artificial lightweight aggregates. Both mined and artificial aggregates [lightweight expanded clay aggregate and expanded glass foam (EGF)] are cost-intensive, location-dependent, and CCE-intensive. H2 has been envisaged by the EU as a futuristic fuel source that can help Europe reach its goal of net-zero CO2 emission. Among the different processes of EE production, turquoise EE (produced from the thermo-catalytic decomposition of CEE gas) has recently gained attention. The process of CEE decomposition is generally attributed to be low CO2 intensive or even, in some cases, net neutral. However, scaling up of this methane pyrolytic hydrogen would also have a three-fold production of pyrolytic carbon. For instance, Hycamite, a Finnish company producing hydrogen from this process, estimates that 6000 tons of carbon will be produced annually from their upcoming plant. Thus, the value addition of this side product can have economic value for its operations. The utility of other carbonaceous residues as a partial replacement for PC has been recently explored in the past decade. For instance, biochar (a carbonaceous residue from wood pyrolysis) usage in limited amounts has proved to be an efficient additive for pore filling, internal hydration curing, and enhancing the carbonation curing potential. Further, Intergovernmental Panel on Climate Change (IPCC) has touted accelerated CO2 curing (ACC) in cementitious composites as one of the efficient and stable CO2 sequestering strategies. The mechanism involves artificially injecting CO2 in a porous matrix that has suitable alumino-oxides that can result in the formation of stable carbonates (Ca, Al, Mg-based). Thus, there is an urgent scope to develop low-emission lightweight aggregates utilizing available side streams in the Finnish context, like waste excavated soft clay, leveraging the CO2 sequestration potential of carbon. Thus, there is a need to come up with lightweight aggregates that are low emission in nature, locally available, and sufficient for strength requirements in the construction sector. Summary of the Invention The present invention aims at solving at least some of the problems of the prior art. In particular, the present invention provides a novel aggregate that acts as an improved alternative for the prior art solutions. It is an object of the present invention to provide a new kind of aggregate, especially a modified aggregate, comprising the combination of a plastic soil and a carbonaceous material. Further, it is an object of the present invention to provide a method of producing such modified aggregate and uses of such modified aggregate. Thus, according to the first aspect the present invention relates to a modified aggregate comprising a plastic soil, a