Case studies of Advanced Construction and Demolition waste(CDW)
Recycling initiatives and technologies In JAPANAffiliation
Location
Position:
Name/Surname
e-mailTitle
ThemeclassificationJDC Corporation
4-9-9 Akasaka , Minato-ku, Tokyo, 107-8466 Japan
Twister Business G, Civil Engineering Department ,Civil Engineering
Division
KENJI OHTSUBO
kenji.ohtsubo@n-kokudo.co.jp
Twister Method(soil improvement device, rotary crushing and mixing method)
Prevention
Re-use〇Technology
development stage〇

RecycleReduce Co2
LegacyBusiness to overseas
Etc.
Practical use
Scheduled to be put into practical use by 2020Scheduled to be put into practical use after 2020

Specific content- The twister method can undertake homogeneous improvement of large
amount of wide-ranging excavated soils generated in the site; soft rocks andconcrete pieces with the diameter of 25 cm or less, clayey soil containing
fine, lump, and high water-containing soils.
This method is the soil improvement technology which consists ofdisentanglement of ground materials by impacting them with several piecesof flexible chains rotating at high speed inside the cylinder as well as
homogeneous mixing with additives. Features are as follows:(1)Wider applicable geological range than conventional(2)Capable of homogeneous mixing of clayey soil lump and clayey soil withhigh water content(3)Capable of crushing of soft rock (grain refining) and grain adjustment(4)Capable of screening wastes, wood chips, and root stocks (with parallel
vibration filter)(5)Plant line-up to cover from small-amount production to mass production
The features realized by the method enables effective utilization of
excavated soils that have been difficult to handle with the conventional
method. About 5.45 million m3 have been utilized successfully for
restoration works in Tohoku disaster-affected areas, disaster stricken areas
and for airport filling project.

Appeal point- High quality and low cost-92-

Twister Method(soil improvement device, rotary crushing and mixing method)

1. What is the technology to recycle the excavated soil by“Twister Method”?
Excavated Soils , such as clayey soil with high moisture content and soil mixed with soft rock,have been difficult to handle according to the conventional method. This new technology canimprove these soils into high-quality banking material, which is dense and easy to compact,
by stirring and mixing them homogeneously.
Utilization of this technology has enabled utilization of wide-variety of excavated soil, which inturn is expected to reduce the work costs and improve the recyclability and quality.
[Applicable public works fields]
1) Banking and embankment works of rivers(Work to reinforce new and existing dykes)
2) Filled-up ground and roadbed reinforcement work during road construction3) Improvement of soil from excavation of structures, and backfilling

2. Outline of the Twister Method
A “Twister Method” consists of crushing and grain refining (shredding) of two or three types of
excavated soils , by means of striking power of multiple flexible chains rotating with high speed
inside the cylinder. This is followed by even dispersion of these soils. This method has enables
simultaneous execution of crushing and mixing.

3. Features of the “Twitter Method”
One machine of the twitter method has the functions of both mixing and crushing.
This method has superior mixing and crushing, shredding performances, which enables mixingof wide-variety of ground materials from clayey soil to rocks.
This method ensures highly effective dispersion of additives and superior stirring
performance.
The left figure shows comparison of the improved-soil quality between this method and manual
mixing. It is evident that improved soil according to this method can attain the required quality
by means of quicklime additive rate similar to the case of manual mixing in the perfectmixing state.

-93-