December 15, 1999 High-quality Recycled Aggregate "Cyclite" Acquires First Approval of Innovative Building Technologies from Building Center of Japan Takenaka Corporation Cyclite - high-quality recycled aggregate developed jointly by Takenaka Corporation (President: Toichi Takenaka; Head Office: Osaka), Takenaka Civil Engineering & Construction Co., Ltd. (President: Koichi Takenaka, Head office: Tokyo), Masaru Yamada, Professor, Faculty of Engineering, Osaka City University, and Kurimoto Ltd. (President: Yoshiaki Sakamoto, headquarters: Osaka City) has recently been certified under the Building Center of Japan's Innovative Building Technology Approval Program (*1) Cyclite grinds crushed concrete lumps 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. Note: (*1): An evaluation program started by the Building Center of Japan with the aims of certifying quality in new technology that is not stipulated by existing standards and legal standards, thereby contributing to the promotion of the development and diffusion of new technology, and ensuring the quality of buildings. Background Concrete waste, which accounts for the largest percentage of construction byproducts, according to a survey of actual conditions carried out by the Ministry of Construction in 1995, has reached 37% of the total quantity of construction byproducts emitted, or a weight of approximately 3.6 million tons. Promoting the recycling of this waste has become extremely important in terms of environmental conservation and resource saving. Generally around two-thirds of concrete waste is recycled, mainly as road base or as backfill. Within Takenaka some 76.6% of concrete waste was recycled in 1998. However, the recycling of concrete in buildings up until now has been restricted to nonstructural sections of buildings (i.e., not including columns, beams, slabs, etc.) apart from experimental cases of applications.a Method of Manufacturing Cyclite Cyclite was developed based on the understanding that the aggregate in concrete is also an important resource that can be used repeatedly. The system for manufacturing Cyclite comprises two stages: the pretreatment which crushes scrap concrete waste and removes other components in the mixture, and the grinding which processes the surface of the lumps of crushed concrete. Grinding is carried out by an eccentric rotor-type(*2) processing unit. The lumps of crushed concrete input between the outer cylinder and the inner cylinder which rotates eccentrically (eccentric rotor) grind against one another, and only the unnecessary cement and mortar attached to the aggregate surface is removed. The resultant material is then put over a sieve, with Cyclite being recovered. Maximum production capacity is 60 tons/hour. Note: (*2): The concept devised by Professor Emeritus Atsuhiro Honda et al., Osaka City University was implemented

The Environmental Burden (CO2 Generated) when Cyclite is Manufactured The only energy required for manufacture is the power (electricity) required to move the crushing and grinding machinery; there is no heating or chemical treatment, which means it consumes around the same energy consumption (CO2 generated) as ordinary broken stone production. Quality of Cyclite The quality of Cyclite satisfies the standards for natural aggregate and crushed stone stipulated in JIS (Japanese Industrial Standard) and JASS (Japanese Architectural Standard Specification), and meets all standards stipulated by the Building Center of Japan for certification of technology. Concrete prepared using Cyclite has the same performance of that created using ordinary concrete.

Example of Application Takenaka was the first company to use Cyclite Concrete in the structure of a building (part of the first floor, approximately 100 m2) in Japan (in the ACROS Shin-Osaka New Construction Project) in November last year. Some 30 m3 of concrete was laid, with the weight of Cyclite being 30 tons.

Artist's Impression of Completed Building

Overview of ACROS Shin-Osaka New Construction Project Location Yodogawa-ku, Osaka Design Takenaka Corporation Construction Takenaka Corporation and one other company (JV) Total floor space 24,850m2 Structure Steel (S), Steel-framed reinforced concrete (SRC) Number of floors 1 fl. below and 14 fl. above ground, 2 penthouse fl. Construction schedule April 1998 to February 2000

Cost At this point in time, Cyclite Concrete is more expensive than concrete that uses natural aggregate, but adding the cost of disposing of scrap concrete into the equation, there is adequate economic merit in the product if the amount processed reaches a certain level. In the future we hope to expand the number of buildings in which Cyclite is used, promote group management to ensure the cycle of scrapping/recycling/concrete production/application runs smoothly, improve the efficiency of recycling, and work to reduce costs, while at the same time striving towards concrete recycling that includes recycling of fine aggregate.