APPLICATION of BASIC OXYGEN FURNACE SLAG in SELF-COMPACTING CONCRETE – DEVELOPMENT and BEHAVIOR
The objective of this study is to investigate the feasibility of basic oxygen furnace Slag (BOF slag, hereafter), being a waste material from steel industry, in self-compacting concrete (SCC, hereafter). BOF slag, when applied in SCC, may play a role in partially replacing total powder content as required to achieve self-compactability of SCC. In general, at least 400 kg/m3 of cementitious materials is required to form sufficient amount of cohesive cement paste that allows concrete to flow like fluid when mixed with coarse and fine aggregates. As a result, the compressive strength of SCC tends to be higher than required. In order to reduce the amount of total cementitious materials and the cost of materials, some inert mineral particles, such as limestone powder, have been used to develop SCC. The BOF slag is basically inactive and low-cost. It is expected that BOF slag may serve as additive fine particles as supplement of cementitious materials. Therefore, a middle-strength SCC may be manufactured in a relatively affordable cost. In this study, a series of mix proportions of SCC incorporating BOF slag makes were trial mixed to obtain suitable BOF content in partially replacement of cementitious materials, such as cement, blast furnace slag and/or fly ash, etc. Mix proportions of SCC with specified compressive strength of 30 MPa (4,000 psi) or lower were successfully developed. Furthermore, BOF slag was found to possess a minimal reactivity in the existence of cement and blast furnace slag. Some fundamental mechanical properties of SCC made of BOF slag were measured as well. Finally, seismic design concrete columns made of BOF slag SCC were tested with cyclic flexural force to examine the structural behavior of BOF slag SCC. The result of the flexural behavior of BOF slag SCC column is comparable to that of conventional concrete column with identical design strength.