| 摘要: | 氣候變遷是21世紀的熱門話題，工業發展導致溫室效應日益嚴重，尤其二氧化碳排放影響最大，減少建築過程中的碳足跡成為新趨勢。本研究製作直徑10公分、高度20公分的混凝土圓柱試體，額外添加小蘇打和生石灰以水泥重量百分比計，並用廢棄混凝土骨材取代部分細骨材，用氣冷高爐石取代部分粗骨材，透過二氧化碳加速養護將二氧化碳封存於混凝土內。實驗控制兩種養護時間和壓力作為碳化條件，設計兩種碳化時機：拆模後的碳化養護和廢棄混凝土骨材的預碳化。探討不同碳化條件、添加物及碳化時機對混凝土碳吸收潛能的影響，同時進行抗壓強度、彈性模數、中性化、TGA和XRD測試。
結果顯示，二氧化碳吸收受碳養護時間和壓力影響甚大。6小時碳養護時間和4.08bar壓力下，各類混凝土達到最大碳吸收，其中純混凝土試體固碳率最高為6.08%，其次是添加2%小蘇打的試體，固碳率為4.69%，其餘混凝土碳吸收效果較差。結合碳吸收效果和抗壓強度試驗，確定了適當添加物比例：小蘇打2%、生石灰5%、廢棄混凝土骨材和氣冷高爐石各50%。碳養護對混凝土彈性模數係數影響不大，主要受混凝土種類影響；碳養護後試體的中性化深度最高為0.54mm，整體受中性化影響不大。XRD和TGA測試證實了碳酸鈣的存在。養護時間6小時、壓力4.08bar下，添加50%廢棄混凝土骨材的試體顯示最大碳酸鈣質量損失為4.179%。
;Climate change is a popular topic in the 21st century. Industrial development has led to increasingly severe greenhouse effects, with carbon dioxide emissions having the most significant impact. Reducing the carbon footprint during the construction process has become a new trend. This study produced concrete cylinder specimens with a diameter of 10 cm and a height of 20 cm, and added baking soda and quicklime based on the percentage of cement weight. Waste concrete aggregates were used to replace a portion of the fine aggregates, and air-cooled blast furnace slag was used to replace a portion of the coarse aggregates. The specimens underwent accelerated carbon dioxide curing to sequester CO2 within the concrete.
The experiment controlled two curing durations and pressures as carbonation conditions, and designed two carbonation timings: carbonation curing after demolding and pre-carbonation of waste concrete aggregates. The study investigated the effects of different carbonation conditions, additives, and carbonation timings on the carbon absorption potential of concrete. Compressive strength, elastic modulus, neutralization, TGA, and XRD tests were conducted to understand the engineering and microstructural properties of the specimens.
The results showed that CO2 absorption was greatly influenced by the carbonation curing duration and pressure. Under 6 hours of carbonation curing and a pressure of 4.08 bar, various types of concrete reached maximum carbon absorption. Pure concrete specimens had the highest carbonation rate at 6.08%, followed by specimens with 2% baking soda at 4.69%. Other types of concrete showed less effective carbon absorption. Combining carbon absorption effects and compressive strength tests, the appropriate proportions of additives were determined: 2% baking soda, 5% quicklime, 50% waste concrete aggregates, and 50% air-cooled blast furnace slag.
Carbonation curing had little impact on the elastic modulus coefficient, which was mainly influenced by the type of concrete. The maximum neutralization depth after carbonation curing was 0.54mm, indicating minimal overall neutralization impact. XRD and TGA tests confirmed the presence of calcium carbonate. The specimen with 50% waste concrete aggregates showed the maximum calcium carbonate mass loss of 4.179% under 6 hours of curing and a pressure of 4.08 bar. |
