The corrosion behavior of glass and glass-ceramics fabricated with silicate glass frit mixed with 50~70 wt% EAF dust in the acidic solution was analyzed by both heavy metal leaching test and microstructural observation. The crystallization temperature, Tc of glassy specimens was around 850 measured by DTA and the heat treatment temperature to crystallize a glassy specimen was selected as 950 / 1 hr. The spinel crystal peaks were found in XRD analysis for the glass containing dust > 60 wt%. For the glass-ceramics, however, the spinel peaks in a specimen containing dust > 50 wt% was found with weak willemite peaks. The glass and glass-ceramic specimens showed the first stage of corroding reaction according to Clark models in acidic solution. The glass-ceramic specimens showed much lower a heavy metal leaching concentration than that of glass specimens in the corrosion test in acidic solution of pH=2.95. Especially, the glass-ceramics containing dust 60 wt% showed a heavy metal leaching concentration of 66 % Pb, 60 % Zn and 98 % Fe lower than that of glass specimens due to crystal phases formed, thermodynamically more stable than a glass network structure. From the leaching test that more Zn ion leached out than Fe ion, the spinel crystal phase [ZnFe2O4] showed better corrosion resistant in the acidic solution than the willemite [Zn2SiO4].

The artificial aggregates were fabricated from several industrial wastes such as waste white clay at 1100 ~ 1150℃/10min in a rotary kiln and its physical properties were evaluated. The water absorption, porosity and emission rate of aggregates were controlled by changing processing methods or compositions which change the microstructure of specimens. The natural aggregates showed many macro pores(120~180 ㎛), high porosity, high water absorption and low unit weight compared to artificial aggregates, while a porosity of artificial aggregates whose apparent shape is more regular was higher than that of a natural aggregates. Increasing waste white clay content in aggregates enhanced bloating during sintering, so increased the absorptivity of specimens. The void contents influenced a initial water emission and the natural aggregates showed a higher void content compared to artificial one due to their irregular shape. The artificial aggregates having shell structure showed a excellent water release control ability. Especially, for after 6 days, its water emission amount was lower than that of natural aggregates. However, artificial aggregates whose shell is removed through crushing process showed deteriorated water release ability.All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications Ltd, www.scientific.net.

The artificial aggregates (AAs) were manufactured from the parent batch powders consisting of bottom ash produced at thermal power plant and dredged soil by direct sintering method at 1050~1200°C for 10min. The bloating phenomenon could be occurred in AAs due to a gas-capturing caused by large quantity of liquid formed at the specimen surface. Increasing the amount of the Na2O added enlarged the area of black core and size of the macro pores in the aggregates. The inside black core got out of the surface of the specimens sintered at 1200°C showing the rugged and cracked surface, but this morphology did not cause a water absorption to increase.

Plasticity indexes (PI) of clay bodies including bottom ashes (BA) and various wastes by using Atterberg limits were measured for the effective recycling of coal bottom ashes from the power plant. Coal bottom ash (BA)-red clay (RC or simply clay), dredged soil (DS)-BA, coal fly ash (FA)-red clay, DS-FA were used as samples for the PI measurement. From the comparison of clay bodies with BA and DS, PI of DS-BA body was higher than that of BA-red clay body because liquid limit (LL) was high and plastic limit (PL) of DS-red clay was low, respectively. Comparing clay bodies with FA and BA, PI of BA-clay body was higher than that of FA-clay body because both LL and PL of BA-clay body were low. When stone ashes and sewage sludge (SS) were added to BA-clay bodies, PI decreased with increasing both stone ash and sewage sludge contents. It is concluded that the measurement of plasticity index can be used as an indicator of forming performance of green bodies with various compositions.

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