C4S* Research & Development Project* Calcium Carbonate Circulation System for Construction

Cement Clinker(CaO)

Limestone(CaCO3)

Production of CCC(Calcium CarbonateConcrete, CaCO3)

Concrete Structures(CaO)

CarbonateConcrete

CCC products
StockWorldJapan

https://earthstonetexas.com/azul-maya-slabs

CO2

CO2

CO2

CO2

CO2
CO2

CO2

CO2
CO2

 Total CO2 in the atmosphere2,800 billion tons
CO2CO2Formation of limestone bybiological and inorganicprocesses

CO2840 billion tons
30 billion tons

CO2

 CO2 emissions due to calcination
during clinker production

2,100 million tons
26 million tons

CO2

Circulation ofCCC

CaCO3Precipitation
betweenParticles

AirCO2

Calcium Carbonate Concrete
Recycledconcrete
aggregate

 Cumulative amountWorld
55,000 million tonsJapan
2,000 million tons
 Annual
WorldJapan

CO2

CCC

Ca(HCO3)2aq.
→CaCO3+CO2+aq. Calcium

Ca

Ca
CO2

CO2
CO2
Ca

Ca CO2

Ca

Calcium Bicarbonate

Solution
Calciumbicarbonate
Coarsesolution

CaCO3+CO2+aq.
→Ca(HCO3)2aq.
particles
Fine
powders
Concrete Waste

Concrete Waste(CaO)

5th October 2022
Takafumi Noguchi, Professor at the University of Tokyo

Production ofCCC raw materials

Ca(OH)2+CO2→CaCO3+H2O(CaO)x(SiO2)(H2O)+xCO2→xCaCO3+SiO2(gel)+H2O

1

C4S Research & Development Project Carbon negative or neutral➡ CCUS equivalent to CO2 emitted by cement concrete Local production for local utilization➡ CO2 and concrete structures that are ubiquitous Completely recyclable➡ Recyclable as many times as you like with negligible CO2 emission

White Carbon

CO2 sink: 1.0 billion tons/year 1/5 of Blue Carbon
 1/10 of Green Carbon

YearDevelopment and dissemination

2023 Compressive strength with 12 MPa2025 Construction of mock-up structure2030 Construction of several low-rise CCC buildings
1.725 times increase every year
2050 50% of concrete structures made of CCC

Establishment & revision of lawsand standards①Revision of Building Standard Lawof Japan②Development of Japanese Industrial
Standards for CCC③Institutional technical guidelines fordesign and construction of CCC④International standards for CCC

In 2050, CO2 to be captured,utilized & stored as CCC
World 1,000 million tons/yearJapan
12 million tons/year
After 2050
Concrete will become carbon
neutral like wood.

2C4S Research & Development Project
Building
demolition
works

Concretewaste
Transportation

Intermediate
treatment

RoadbedRoadconstruction※Some may be used as roadbed. (assumed zero at this moment)

CCCin C4S

Building
demolition
works

CCC
CCC
CCC
raw material
productionbuilding
production Transportation (heating, cooling, Transportation construction
Transportation
pumping, pressing)(crushing, sieving)
Concrete
waste

Production and execution of reinforcements
Production of formworks

Use ofCCC building

Demolition of
CCC building

Types and methods for reinforcing and formwork
are not yet determined in the project.

Cement production

Conventional
Concrete

Aggregate production
Water production

Precastconcreteproduction(mixing＋heating)PCa concretebuilding
construction

Use of
PCa building

Demolition of
PCa building

Admixture production
Production and execution of reinforcements
Production of formworks
3

Pressuremolding
Strength increase
with size increase
CO2 curing
The greater the increasein calcium carbonate
precipitation, thegreater the increase incompressive strength.

Energy reduction
with increase instrength & size

● φ1x2cm● φ10x20cm
PCa concrete plant (winter)

Cement content 291 kg/m3

Heating

Cementproduction

Base scenarios
Pressing
methodPressing

Heating

CO2 abs.

CO2 abs.

● Compressive strength○ Compressive strength increase

Precastconcreteproduction
PressingPumping
methodPumping not considered

Heating not considered（Literature surveyon tile production）

 Assumed basedon precast
concrete plant
observation
 Decrease inenergy efficiency
for cooling notconsidered

Heating

CO2 abs.

CCC Real scale scenarios

Wind blowing

Heating

Scenario withdecrease inenergy efficiency

Low strength concrete is
assumed. W/C = 65%,

Filling rate (%)
Compressive strength (MPa) &Compressive strength increase (MPa)The higher the fillingrate before curing, thehigher the compressivestrength.

Compressive strength (MPa)C4S Research & Development Project（Based on PJ2 design）

Cooling（Based on thedata on water used.）

CO2 abs.

CCC specimen（precipitation method）

CO2 absorption(PJ2 experimental data）

Calcium carbonate increase (%)
4

CO2 Calculation Assumptions
 Heating and cooling energy for CCC production is calculated based on the amount of water used for CCC
specimen production. 100% energy efficiency is assumed for this process. Water amount is obtained from CCC
experimental data for small specimen.
 Energy efficiency decrease in heating is calculated based on the precast concrete plant observation. However,energy efficiency decrease in cooling is not considered.
 Heated water (70ºC) in CCC production is cooled down to 20ºC in outdoor exposure without any energy
consumption.
 Pressing energy is calculated based on ceramic tile plants data (MJ/m2), and 200 times pressing is assumed for
1m3 CCC production.
 Crushing energy for CCC raw material production is assumed as the same for roadbed materials fromdemolished concrete. The energy may increase depending on the particle size distribution necessary for CCC
production.
 Wind blowing energy during CCC raw material production is calculated based on the machinery inventory data.
The machine operation condition is set based on the laboratory data and the semi on-site data.
 CO2 absorption of CCC is calculated based on experimental and semi on-site data.
 Pumping energy is not considered due to the lack of data in full scale scenario.
 Water spray energy is not considered due to the lack of data in full scale scenario.
 Strength of precast concrete is assumed as low to keep consistency with CCC in strength.
 Heating energy for precast concrete is calculated based on the on-site plant observation.

CCUS with Concrete “White Carbon”
White Carbon

CO2CO2 sink:
1.0 billion tons/year

CO2CO2

Green Carbon

CO2 sink:
10.64 billion tons/year

CO2 1/5 of Blue Carbon
 1/10 of Green Carbon

Crustalresources

CO2Concrete
CO2CO2

CO2

CO2

CO2

CO2

CO2

CO2

CO2CO2CO2

Concrete products

CO2

Ready-mixed
concrete

CO2 CO2CO2Blue Carbon

CO2Binders
Concrete waste

CO2 sink:
5.83 billion tons/year

CO2CO2CO2

Carbon Neutral Concrete toward Ideal CCUS
 Concrete is essential for construction.
 Concrete shall be sustainable like wood.
• Sufficient resources• Well-balanced between raw materials (Ca,Mg, CO2) and products (cement, concrete)• Closed completely recyclable• Locally produced for locally utilized• Economic
CCC (Calcium Carbonate Concrete)
promising candidate

CCC
CO2

Nunes LJR, Meireles CIR, Pinto Gomes CJ, Almeida Ribeiro NMC. Forest Contribution
to Climate Change Mitigation: Management Oriented to Carbon Capture andStorage. Climate. 2020; 8(2):21. https://doi.org/10.3390/cli8020021

Structures
Waste