高壓環境混凝土對二氧化碳的吸附能力初步探討

Preliminary Study on Adsorption Capability of Carbon Dioxide in Concrete under High Pressure

黃毅瑋(YI-WEI HUANG)

指導教授 ： 李明君

朝陽科技大學/理工學院/營建工程系/碩士(2016年)

摘要

本研究以Ｉ型水泥、台灣河砂、三分石料製作成Φ5×10公分圓柱體的混凝土試體，將各項參數製成之混凝土試體於新拌後靜置150分鐘使其達到初凝狀態後拆模，放入二氧化碳氣體環境下進行加速養護試驗，探討混凝土對二氧化碳的吸附能力。試驗為三種壓力、三種水灰比、三種時間及兩種二氧化碳濃度搭配製作混凝土圓柱試體，研究得知二氧化碳濃度100%、加壓時間180分時試體的碳吸附量較高，每組皆進行抗壓測試，取強度或吸取二氧化碳能力較佳之濃度和壓力參數組合進行XRD試驗，分析微觀試體表面生成碳酸鈣結晶，並進行SEM試驗分析試體表面的結晶物結構變化，部分結晶物以0.1~0.2 μm的尺寸組成，當試體表面的結晶物尺寸越小，試體強度越高，但因試體接觸的CO2濃度及反應時間不足，後期C-S-H矽鈣膠體生成速率大於CaCO3碳化速率，導致試體中性化試驗後的碳化深度皆為0公分。由XRD試驗判斷吸附二氧化碳越多其強度越低。最後以碳足跡計算排放量與養護吸碳量，得知養護吸附效果遠低於其二氧化碳排放量，大約10%吸附量。吸收最多二氧化碳之組別為0.5水灰比、濃度100%、壓力6 bar、養護時間180分鐘，二氧化碳養護加快了終凝速度但降低了些許之強度。

關鍵字

二氧化碳養護 ； 碳足跡 ； 碳酸鈣結晶 ； 抗壓強度 ； 碳化深度

並列摘要

In this study, concrete specimens of Φ5 × 10 cm cylinders were made with Portland I cement, Taiwan river sand and 3/8’’-stone. The specimens made by different parameters were placed around 150 minutes for molding. After the state of mold removal, the specimens were put into the carbon dioxide gas environment to accelerate curing tests and to study the adsorption capacity of carbon dioxide. The parameters of this study included three pressures, three W/C ratios, three curing times and two CO2concentrations. The results show the higher absorption of CO2 occurs with 100% CO2-180 minutes conditions among the experiments.
After the pressure test, XRD (X-ray Diffraction) and SEM analysis were carried out with higher strength specimens or better carbon dioxide absorption ones to analyze the precipitation of calcium carbonate on the surface. Part of the precipitation sizes are around 0.1~0.2 um. The smaller precipitation sizes on the surface, the higher strength performance. But due to insufficient reaction time and concentration, the formation rate of C-S-H gel is higher than calcium carbonation. It causes the specimen without any carbonation depth. From the XRD results, the more carbon dioxide absorbed, the lower strength performed.
Finally, the carbon emission is higher than the carbon absorption in these curing experiments by the carbon footprint calculation. The best carbon dioxide absorption rate is only around 10% in W/C 0.5-100% CO2-6 bar-180 min sample. Carbon dioxide curing accelerates the final setting rate but reduced the strength.

並列關鍵字

carbon dioxide curing ； carbon footprint ； calcium carbonate crystallization ； compressive strength ； carbonation depth

參考文獻

[16] 江權洲，「特殊混凝土對二氧化碳的吸附能力之探討」，中原大學土木系，碩士論文，2015年。

[9] 林永值，「輕質骨材混凝土對二氧化碳吸附之初步探討」，朝陽科技大學營建系，碩士論文，pp.15-18，2014年。

[1] 黃慶慶，「鹼活化電弧爐還原碴製作混凝土可行性研究」，國立中央大學土木工程研究所，碩士論文，2008年。

[5] Shao, Y., Mirza, M. S., and Wu, X., “CO2 Sequestration using calciumsilicate Silicate concrete”, Canadian Journal of Civil Engineering, 33, 776-784, 2006.

[6] Goodbrake, C. J. and Young, J. F., “ Reaction of Beta-Dicalcium Silicate and Tricalcium Silicate with Carbon Dioxide and Water Vapor ”, Journal of the American Ceramic Society, 168-171,1979.