CELBIC (Environmentally Friendly BF Concrete) A Group of Thirteen General Contractors Obtained a Certificate of Technical Performance for Construction Materials to Promote its General Use

The CELBIC Study Group (consisting of thirteen companies: Haseko Corporation (organizer), Asunaro Aoki
Construction Co., Ltd., Asanuma Corporation, Hazama Ando Corporation, Okumura Corporation, Kumagai Gumi
Co., Ltd., Konoike Construction Co., Ltd., Penta-Ocean Construction Co., Ltd., The Zenitaka Corporation, Tekken
Corporation, Tokyu Construction Co., Ltd., Toyo Construction Co., Ltd, and Yahagi Construction Co., Ltd.) has
obtained a Certificate of Technical Performance for Construction Materials (GBRC Material Certification No. 20-
02) from General Building Research Corporation of Japan as of October 5, 2020 for “Environmentally Friendly
BF Concrete (CELBIC)”, a concrete made of ordinary Portland cement mixed with 10-70% ground granulated
blast-furnace slag.

 

CELBIC, an acronym for “Consideration for Environmental Load using Blast Furnace Slag In Concrete”, is an
environmentally friendly concrete that reduces carbon dioxide emissions from concrete materials by approximately 9 to
63% while ensuring the quality of concrete required for construction of concrete structures, aiming to contribute to
establishing a sound material-cycle society and solving global environmental issues. CELBIC can be manufactured and
shipped as a concrete conforming to JIS A 5308 (ready-mixed concrete) and will be constructed under the responsibility
of the thirteen companies participating in the CELBIC Study Group.

 

In the future, we will apply this environmentally friendly CELBIC effectively and efficiently to buildings and other
reinforced concrete structures in order to encourage the widespread use.

 

■Environmental considerations

Ground granulated blast-furnace slag is made by pulverizing by-product slag produced during pig iron making in the
blast furnaces of ironworks and has hydraulic properties.
Since the amount of carbon dioxide emitted during the manufacture of ground granulated blast-furnace slag is less
than 1/20 than that of ordinary Portland cement, effective use of this granules is desired to reduce the environmental
impact.
Ground granulated blast-furnace slag is a concrete material used as a substitute for cement as one of the admixture
materials under JIS A 5308 (ready-mixed concrete). In general, it is distributed as blast furnace slag cement class B,
which is pre-mixed with Portland cement in a prescribed amount (at 40-45%) at a cement plant.

 

■Features

CELBIC is produced in a ready-mixed concrete plant using ordinary Portland cement and ground granulated blast-
furnace slag as the concrete material, and according to the application parts or components of the building and the
specified performance, 10% to 70% of the cement is replaced with ground granulated blast-furnace slag.
CELBIC is classified into three classes according to the amount of ground granulated blast-furnace slag: Class A,
Class B and Class C.
Of these, Class A has performance similar to concrete made of ordinary Portland cement, while Class B has
performance similar to that of blast furnace slag cement Class B. Class C reduces carbon dioxide emissions by more
than 60%, although the application at sites are limited. In addition, since these three types of CELBICs use the same
ground granulated blast-furnace slag, the burden of material management at the ready-mixed concrete plants is
alleviated, and generic application for building structures by taking advantage of the distinctive features of each type
is expected.

 

■Development experiment

In the development experiment, we confirmed the strength development and durability of concrete under various
conditions using several kinds of ground granulated blast furnace slag mainly distributed in Japan, and verified the
basic performance of the concrete according to the content ratio of ground granulated blast-furnace slag.
Based on the results, we determined the selection of the plant and the method of concrete mix design, followed by
the construction verification assuming the manufacture of CELBIC and actual parts and components at the actual
ready-mixed concrete plant, and prepared the mix design & construction manual for CELBIC.