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Project managers greeting

Noguchi Takafumi

Realizing a carbon-neutral society in 2050 and keeping the average temperature rise of the earth after the Industrial Revolution sufficiently below 2°C is now the highest proposition of all the world and all industries. The construction industry is no exception, but rather expected to play a leading role.
Concrete is an indispensable construction material for buildings and civil engineering structures that support our activities, but in the production of cement, which is a main raw material for concrete, a large amount of limestone, which is a finite natural resource, is used and a large amount of CO2, which is a global warming substance, is emitted. The ratio of limestone reserves to production is about 100 years, and about 7% of 33 billion tons of CO2 emitted annually worldwide comes from cement production.
To fundamentally solve the problems of resource depletion and CO2 emissions in cement and concrete, research and development is conducted. Ca in concrete accumulated as buildings and civil engineering structures is regarded as a potential unused resource capable of capturing CO2. Concrete waste, which is generated by the demolition of buildings and civil engineering structures, and atmospheric CO2 are recycled as Calcium Carbonate Concrete (CCC). By putting CCC into practical use as a main construction material to replace conventional concrete, a new resource circulation system ( C4S : Calcium Carbonate Circulation System for Construction) will be realized. In other words, it is said that a huge amount of CO2 was taken in as limestone when the Himalayas and Alps rose hundreds of millions of years ago, and as a result, the temperature of the earth dropped. Our project aims to reproduce it.

With the realization of C4S , a large amount of concrete that exists all over the world will be revived as CCC. Since CCC can be recycled many times with low energy, it will continue to support human activities for a long time as a carbon-neutral and completely recyclable construction material like wood. As a result, global warming will be greatly suppressed and valuable natural resources will be conserved, and it is expected that the global environment will be fundamentally regenerated.
We are enthusiastically promoting research and development with the goal of implementing CCC in society in 2030. In addition to technological development, we plan to solve piled up issues one by one, such as establishing standards, reforming legal systems, improving supply chains, and so on. We really appreciate your cooperation and support.

The ratio of limestone reserves to production is about 100 years


about 7% of 33 billion tons of CO2 emitted annually worldwide comes from cement production. 


Production of CCC


Outline of Research and Development

The group consisting of the University of Tokyo, Hokkaido University, Tokyo University of Science, Utsunomiya University, Shimizu Corporation, Taiheiyo Cement, and Masuo Recycle is implementing the NEDO Moonshot R & D Project "C4S Research and Development Project" (C4S : Calcium Carbonate Circulation System for Construction) with the aim of making a significant contribution to the realization of a carbon-neutral society and a resource-recycling society. In the project, CO2 that is thinly spread in the atmosphere and concrete waste generated by the demolition of structures that exist all over the world are regarded as construction resources. We are conducting various research and development on the new concrete for next generation that can be recycled many times and become carbon neutral, that is, calcium carbonate concrete (CCC), using only CCO2, concrete waste and water. The current research and development issues of the project are classified into the following three categories.

nvestigation of manufacturing principle and development of manufacturing technology for CCC, which is produced by flowing a calcium bicarbonate solution between concrete waste particles (aggregate for CCC) that are in close contact with each other, precipitating calcium carbonate crystals by various controls, and binding the concrete waste particles to each other

Development of efficient crushing method for concrete waste and efficient CO2 capture method using concrete waste for producing aggregate for CCC with optimum particle size distribution and carbonation rate

Examination of various issues for social implementation of CCC, including evaluation of various performances of CCC, development of design method of CCC structure, establishment of laws and standards required for CCC structure, optimal resource recycling scenario in C4S , and analysis of LCCO2 reduction effect in C4S )

performance goal

By conducting these researches and developments, we aim to demonstrate that CCC with performance equal to or better than conventional concrete can be manufactured with low energy by February 2023, a mock-up structure using CCC can be constructed by 2025, a couple of low-rise buildings can be constructed using CCC by 2030, and half of Japan's concrete structures will be constructed using CCC by 2050.

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