Kohji Kakimoto*, Yasuko Nakano*, Hiroaki Ogawa*, Yoshito Shirai** and Yasuhiko Kato***

* Department of Applied Chemistry, Faculty of Engineering, Kyushu Institute of Technology
** Department of Biochemical Engineering and Science, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology
*** Professor Emeritus of Kyushu Institute of Technology

+ Correspondence should be addressed to Kohji Kakimoto:
(1-1 Sensuicho, Tobata-ku, Kitakyushu-city, Fukuoka 804-8550 Japan)

Abstract

In order to utilize the slag discharged in the steelmaking process, as road base course materials, several methods including: aging; addition of chemicals; and reducing the period of aging; have been proposed to minimize the deteriorative expansion-disintegration property. However, slag in which the expansion potential has been minimized by these methods, would not satisfy the criteria of strength (unconfined compressive strength) to be used as base course (hydraulically and mechanically stabilized slag, 'HMS'), because these methods have a negative effect on the self-hardening property of slag. Thus, the purpose of this paper is to experimentally evaluate the effectiveness of a newly proposed method in which other by-products (coal ash and sludge discharged from construction work) are added to the slag, in order to minimize expansion potential, as well as to maintain strength development. Results of the expansion and unconfined compressive strength tests, show that the addition of fluidized bed combustion coal fly ash and construction sludge, is considered to be an effective method for improving the property of the slag, as well as enabling the utilization of the mixture for base course construction, as HMS.

Key words: hydraulically and mechanically stabilized slag, construction sludge, steelmaking slag, coal ash