碳酸化對燃煤飛灰無機聚合材料特性影響之研究

A Study on the Properties of Coal Fly Ash Geopolymer Affected by Carbonation

盧子威(Tzu-Wei Lu)

指導教授 ： 柯明賢

國立臺北科技大學/工程學院/資源工程研究所/碩士(2012年)

https://doi.org/10.6841/NTUT.2012.00070

摘要

本研究使用燃煤飛灰與氫氧化鈉溶液合成之無機聚合材料進行碳酸化實驗，以探討無機聚合材料於二氧化碳氣氛下其特性之變化，利用燃煤飛灰與氫氧化鈉溶液以固定之液固比製成粒徑為1.5×3.0 cm之柱狀與0.8cm之粒狀無機聚合材料，並分別進行室溫養護與溫度200℃、水氣組成40%、二氧化碳組成60%之碳酸化養護，之後分別取養護7天、14天與28天之試體進行各項特性分析，以探討碳酸化對於無機聚合材料於養護階段其特性變化之影響。另外，本研究亦將室溫養護28天後之試體進行28天之碳酸化實驗，並進行各項特性分析，以探討碳酸化對於無機聚合材料特性之影響。
由結果可發現柱狀試體在碳酸化養護下於7天時其抗壓強度遠高於室溫養護，而到了第14天時其抗壓強度驟降，低於室溫養護之試體。由試體切片之SEM發現在試體外層形成較為緻密之結構，而由pH值分析可發現7天至14天之碳酸化養護之試體的pH值為11，到了28天時其pH值降至10。又碳酸化養護28天試體之抗壓強度及熱重分析與碳酸化養護14天之試體均無明顯差異，顯示碳酸化養護之試體其無機聚合反應到了14天之後可能受碳酸化之影響而停止。本研究進一步將室溫養護28天後之柱狀無機聚合材料試體再進行溫度200℃、水氣組成40%、二氧化碳組成60%之碳酸化實驗，由結果可發現在經過室溫養護28天後之試體在經過碳酸化其抗壓強度僅略微下降，顯示柱狀之無機聚合材料其抗壓強度不受碳酸化影響，而由熱種分析結果顯示室溫養護後之無機聚合材料可作為二氧化碳之吸收材，值得進一步探討。
而由粒狀無機聚合材料的研究結果可發現在碳酸化養護下於7天時其抗壓強度遠高於室溫養護，而到了第14天時其抗壓強度雖驟降，但仍高於室溫養護之試體，直到第28天其抗壓強度才較室溫養護之試體為低。而由pH值分析可發現碳酸化養護之試體在第7天時之pH值約為11，而到了第14天後其pH值下降至10.8，且到了28天後其pH值約為10.4。之後進一步將室溫養護28天後之粒狀無機聚合材料進行溫度200℃、水氣組成40%、二氧化碳組成60%之碳酸化實驗，由抗壓強度分析結果可發現在28天碳酸化養護後無機聚合材料之抗壓強度由25Mpa上升到30MPa，顯示粒狀無機聚合材料在碳酸化後其抗壓強度有上升的趨勢。
綜合本研究結果可發現，無機聚合材料如要得到早期高抗壓強度，可於二氧化碳氣氛下進行碳酸化養護，不僅於7天內可得到較高之抗壓強度，亦兼具二氧化碳之吸收作用。而經28天室溫養護後之無機聚合材料則會有較佳之二氧化碳吸收能力，且碳酸化對其抗壓強度不會產生顯著的影響。

關鍵字

無機聚合材料 ； 燃煤飛灰 ； 碳酸化 ； 抗壓強度 ； 熱重分析

並列摘要

The aim of this study was to utilize coal fly ash and NaOH solution to prepare 1.5×3.0 cm pillared and 0.8cm granular geopolymer, and the carbonation test would be used to investigate the effects of carbonation on the properties of geopolymer. The both geopolymers were respectively cured in the atmospheric and carbonation(temperature 200℃, 40% H2O, 60% CO2) conditions. Besides, another carbonation test(temperature 200℃, 40% H2O, 60% CO2) was performed after 28 days atmospheric curing. To analyze the compressive strength, pH and TG of geopolymer cured after 7, 14, 28 days was used to evaluate the effects of carbonation on geopolymer.
The results indicated that the compressive strength of pillared geopolymer curing with carbonation was higher than curing with atmosphere after 7 days. The compressive strength of geopolymer curing with carbonation after 14 days decreased with curing time and was lower than curing with atmosphere. The SEM photographs showed that the outer layer microstructures of geopolymer became more compact. Furthermore, the pH analysis showed that the pH of geopolymer was 11 after 7~14 days and the pH decreased to 10 after 28 days. The compressive strength and TG analysis of geopolymer cured after 28 days did not obviously change compared with cured after 14 days. It implied that the geopolymerization of geopolymer could shut down due to the carbonation after 14 days. Besides, the carbonation of geopolymer cured with atmosphere after 28 days was also performed. The results indicated that the compressive strength of pillared geopolymer was not affected by carbonation and the cured geopolymer was a good absorption material of CO2.
The results indicated the compressive strength of granular geopolymer curing with carbonation was higher than curing with atmosphere after 7 days. The compressive strength of geopolymer curing with carbonation after 14 days decreased with curing time but was still higher than curing with atmosphere. The compressive strength of geopolymer curing with carbonation after 28 days was lower than curing with atmosphere. Furthermore, the pH analysis showed that the pH of geopolymer was 11 after 7 days and the pH respectively decreased to 10.8 after 14 days and 10.4 after 28 days. Besides, the carbonation of geopolymer cured with atmosphere after 28 days was also performed and the results indicated that the compressive strength of granular geopolymer would become higher
Based on the results of this study, it implies that the compressive strength of geopolymer in the carbonation curing would reach higher than in the atmosphere curing after 7 days. The geopolymer curing in the atmosphere condition after 28 days would have the better absorption capacity of CO2 and the compressive strength of geopolymer curing in the atmosphere condition after 28 days was not obviously affected by the carbonation.

並列關鍵字

Geopolymer, Coal fly ash ； Carbonation ； Compressive strength ； TG analysis

參考文獻

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