No abstract

The use of fossil fuels is steadily increasing. The thermal power generation industry uses a lot of energy and emits a large amount of greenhouse gases. On the other hand, a desulfurization facility can be installed to remove sulfur content during boiler combustion process of the power plant. Dry desulfurized gypsum generated from dry desulfurization facilities is suitable as a CO 2 absorbing material due to the presence of CaO. In this study, the carbonation properties of dry desulfurized gypsum were investigated by carbonizing dry desulfurized gypsum via mixing with water and stirring. As a result of microstructural, XRD and thermal analyses of the carbonized dry desulfurized gypsum, the carbonation age was found to be suitable for 16 h. Dry desulfurized gypsum absorbs about 16% of CO 2 per unit weight.

In this study, fabrication method of inorganic insulation were studied to reduce CO 2 from buildings. Main materials for inorganic insulation were used cement, blast furnace slag and aluminum powder as foaming agent. Mixing ratio of cement and slag was controlled and physical properties of inorganic insulation were analyzed. When inorganic insulation was fabricated using cement and slag, expanded slurries were not sunken and hardened normally. Pore size was 0.5-2 mm; mean pore size was about 1mm in inorganic insulation. Compressive strength of inorganic insulation increased with curing time and increased slightly with cement fineness. However, specific gravity decreased slightly with curing time; this phenomenon was caused by evaporation of adsorptive water. When inorganic insulation was dried at 60 o C, compressive strength was higher than that of undried insulation. The highest compressive strength was found with a mixture of cement (50%) and slag (30%) in inorganic insulation. Compressive strength was 0.32 MPa, thermal conductivity was 0.043 W/mK and specific gravity was 0.12 g/cm 3 .

For the purpose of reducing the amount of limestone, which is used as a desulfurization agent to absorbing SO X gas in thermal power plants, and to recycle limestone sludge generated from a steel mill, limestone sludge was utilized as a desulfurization agent. In this study, cement, made of flue gas desulfurization (FGD) gypsum obtained in a desulfurization process using limestone sludge, was manufactured then, experiments were conducted to identify the physical properties of the paste and mortar using the cement. The results of the crystal phase and microstructure analyses showed that the hydration product of the manufactured cement was similar to that of ordinary Portland cement. No significant decline of workability or compressive strength was observed for any of the specimens. From the results of the experiment, it was determined that FGD gypsum manufactured from limestone sludge did not influence the physical properties of the cement also, quality change did not occur with the use of limestone sludge in the flue gas desulfurization process.

This paper presents an experimental study for the purpose of reducing the cost of producing ultrahigh performance fibrereinforced concrete (UHPFRC). Reject fly ash (r-FA) and recycled glass powder (GP) were examined as replacement materials for the silica sand and cement used to prepare UHPFRC, respectively. In addition, curing UHPFRC specimens at 25• C and 90• C was investigated to determine differences in mechanical properties. The results showed that using r-FA and GP reduces the flowability of fresh UHPFRC. The use of GP increased the mechanical properties of the UHPFRC. Moreover, the test results indicate a significant improvement in the mechanical properties of plain concrete by the inclusion of r-FA as partial replacement of fine aggregate (sand) and can be effectively used in UHPFRC. Furthermore, specimens cured at 25• C give lower compressive strength, flexural strength, and fracture energy than specimens cured at 90• C.