Friendly construction 3Rs
Challenge toward zero emissions

In Japan, of the total substance input volume annually around 40 percent is used in the construction industry. It is also said that around 20 percent of the amount of emissions from industrial waste materials comes from the construction industry. The recycle ratio of construction waste materials is over 90 percent, and continues to rise annually. However, in addition to the promotion of recycling, limiting the generation of refuse (“reduce”) is also an important subject.

For example, measures are being taken to maximize the control of the generation of construction waste materials before materials are taken to the work site, such as materials being precut to required measurements at plants, and equipment and piping being built into units. In addition, as much as possible, the protective frames and packing materials of parts and materials such as cardboard boxes and plastic wrapping are not used at the site with simple packaging being used such as corner protections, and PP bands. Otherwise, returnable pallets, containers or cases are being used to avoid packaging.

Separation yards are installed at work sites, and methods are being used such as developing special containers for collecting the separated refuse, where the contents can be easily seen, so thorough separation is made. They are then sent to the specific asset recycling centers. At the same time, effort is being put into educating the workers.

With regard to gypsum boards from demolition work, a large amount of which up until now has been disposed of, because they could not be recycled, through a network consisting of Takenaka, the board manufacturers, and industrial waste disposal companies, Takenaka has coordinated the establishment of “Gypro Co.,” so the company participates itself in contributing to the promotion of recycling in the industry as a whole.

The disposal of some complex materials, which are a mix of different waste materials and are therefore difficult to separate, remains a problem at work sites. Because there is a lack of facilities to handle these difficult by-products, in a linkup with local governments, the construction industry, the industrial waste disposal industry and manufacturers, Takenaka has participated in the establishment of “Recycle Peer Co., Ltd.,” a construction-related mixed waste products intermediate treatment facility and is participating in this activity with the aim of improving the recycling of construction waste materials.

*The base, which is the foundation of a building, has the extremely important role of preventing the building from sinking as well as maintaining the strength of the building against earthquakes. Because the base structure is in the ground, a large amount of soil must be excavated during construction. Most of this becomes surplus soil and must be disposed of at another site. With the “Multilevel Expanded-Diameter Pile Method,” by changing way superhigh-rise buildings are supported, the amount of soil that needs to be excavated can be drastically reduced. Also, with the “Piled Raft Foundation Method used with the Grid-Form Deep Mixing Ground Improvement Method (TOFT Method),” the improved ground, can act as piles to prevent any liquefaction in weak ground during an earthquake. Both the number and the length of the piles can be reduced, thereby greatly reducing the amount of soil that needs to be disposed of.

*Takenaka is developing and using various types of environment-friendly technologies, including technology for “Improving the Quality of Construction Surplus Soil for Use in Planting,” the “Continuous Diaphragm Wall Method Using Excavated Soil,” and the “Recharge Method,” which can return pumped-up groundwater to its origin for conserving and securing groundwater systems, and reducing the drainage rate.

*“Cyclite” is the name of a high-quality recycled aggregate. To produce “Cyclite,” crushed concrete lumps are ground together using a newly developed processing unit, thereby removing the mortar from the aggregate surface without crushing the aggregate. This gives it the same quality as natural aggregate and crushed stone. Recycling the aggregate in concrete waste materials generated when a building is torn down is the first step in cyclical recycling of concrete.