This study classified oyster shells that produced as a industrial waste into 3 distribution by washing, drying and processing them. Mortar specimens with a constant ratio by using this to substitute fine aggregates were made, and the specimens were heated under the heating conditions of 300℃, 600℃ and 900℃ based on the 28-day age. On the age of 28 days, the plain flexural strength was found to be 9.2MPa, and in O 0.15, it was shown to be 4.4∼ 7.9MPa depending on the substitution rate. It was found to be 4.4∼7.7MPa in O 1.2∼2.5 depending on the substitution rate, and last but not least, it was shown to be 6.1∼8.8MPa in case of O 2.5∼5.0 depending on the substitution rate. In case of the compressive strength of the 28-day age, it showed the difference of 23.6∼43.2MPa in O 0.15 depending on the substitution rate, and 20.4∼45.1MPa in O 1.2∼2.5 depending on the substitution rate, and last but not least, 17.1∼40.4MPa in case of O 2.5∼5.0. As a result of measuring the residual strength through heating, in case of substituting fine aggregates less than O 0.15 by 100%, it showed the lowest strength reduction ratio, and it is expected that the heat-resisting property could be achieved through processing and proper mixing of oyster shells through these results.

In this study, oyster shells were processed and classified into sizes equal to or smaller than the fine aggregate threshold, and their engineering properties and fire-resistant performance were examined. The differences in heating weight loss of oyster shell aggregate (OSAs) with different particle sizes were examined using thermogravimetric analysis (TGA). The TGA results showed indicating that the temperature at which decarboxylation reaction started depended on the OSA particle size. The porosity of mortar specimens was analyzed using mercury intrusion porosimetry (MIP). The porosity area and porosity of the OSA-containing mortar increased with decreasing particle size. Mortar fire-resistant boards with heated for 2 h in accordance with the heating conditions of KS F 2257-1(methods of fire-resistant testing for structural element—general requirements) to measure their back-side temperature. The board made with OSA2.5 exhibited 273.2 °C, which is more than 90 °C higher than the back-side temperature of the board with OSA 0.6Under. Such difference was attributed to the greater heat transfer delay caused by higher porosity, porosity area, and specific surface area in OSAs with small particle sizes. The TGA results combined with the heating test results suggested that CO2 would be generated at different temperatures in boards containing OSAs with different particle sizes because of the differences in the endothermic reaction temperature.

No abstract

No abstract