The Study on the Mechanical Properties of Waste Oyster Shells with Mineral Admixture used in Cement Mortar

• Main Authors: Po-Yu Chen, 陳柏佑
• Other Authors: Her-Yuan Wang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/00877629313672209121

碩士 === 國立高雄應用科技大學 === 土木工程與防災科技研究所 === 99 === The oyster shell is the by-product from the shellfish farming. Most of them are disposed to landfill without preprocessing and caused the serious environmental problems. In this study, the recycled oyster shell sand is used to replace fine aggregate. The water-to-cement ratio (W/C) of all mixture proportions was controlled at 0.485. Some of mortar specimens were mixed by using four replacements of 0%, 5%, 10% and 15% with recycled oyster shell sand, respectively. The others were mixed by using five replacements of 0, 5, 10, 20 and 30% by weight with the mixture of ratio 1:1 oyster shells and slag or fly ash, respectively. The fresh, harden and durability properties of mortar were tested. Finally, the feasibility of application for engineering was also evaluated. The experiment result shows that the reduction of fluidity ratio is range of 3.1-9.5% due to increase oyster-shell replacement. By comparing to control group, the initial and final setting time of mortar with oyster-shell replacement decreased 13-53 minutes and 75-125 minutes, respectively. The compressive, flexile and tensile strength of specimens at 28 days age was about 85, 81 and 80% compared to control group, respectively. The increasing of absorption is range of 6-11% and the volume changed is about 0.072%. Both results were higher than the controlled group. The chloride ion content of mixtures is range of 0.081-0.139 kg/m3 and meets the standard. The sulfate resistance ability of mixtures decreased since the oyster shell has a large amount of pores and its higher absorption. On the other hands, the result of mortar consists of oyster shells and mineral admixture, show that the increasing of fluidity ratio is range of 2.1-4.3%. For the mixture with the replacement of oyster shell and slag, the increasing of initial and final setting time was range of 28-95 minutes and 96-235 minutes, respectively. For the mixture with the replacement of oyster shell and fly ash, the increasing of initial and final setting time was range of 18-83 minutes and 70-180 minutes, respectively. The compressive strength in early age is similar to the control group. Comparing to the control group, the increasing of compressive strength is range of 2-22%and the decrease of absorption is range of 1.4-6.5% after 56 days age. The volume change ratio is above 0.055% and it is lower than the control group. The chloride ion content of mixtures is range of 0.056~0.146 kg/m3 and also meets the standard. The ability of sulfate resistance was increasing since the pozzolanic effect is occurred from slag or fly ash and the hydration product filled the pores of mortar. The engineering properties of mortar consists the proper amount of oyster shells are similar as cement mortar. According to the concept of the sustainable development and the green building material, the oyster shell waste can be recycling used after appropriate processing. The feasibility of application for engineering was successful by concerning of source, engineering properties, technology, and economic. According to this study, a solution for reduce and recycling used the waste was provide and improve the sustainable development. It also contributes to the program for environmental action and the sustainable development of the Earth is also helpful.