微米气泡和超声波辅助湿法碳化再生微粉及人造骨料试验

Experiment on mircon bubbles and ultrasonic-assisted wet carbonation for recycled micro-powder and artificial aggregate

摘要:

再生微粉具有优异的固碳潜力,湿法碳化方法有助于更好地发挥其固碳性能。为此,采用微米气泡和超声波辅助的方法改善湿法碳化的固碳效率,对固碳后的再生微粉浆料通过压制成型的方法制备人造骨料,进一步利用二次碳化方法驱动人造骨料强度提升,并提出铝膜袋CO₂体积法对再生微粉固碳量和碳化程度进行评价。最后,对此产品进行碳足迹核算。结果表明:提出的改进湿法碳化方法可以有效提高再生微粉碳化效率,用铝膜袋CO₂体积法对再生微粉进行固碳量评价的方法操作简单、实用；再生微粉在常温、常压、100% CO₂体积分数的铝膜袋中0.5 h固碳量,与本研究提出的湿法碳化方法的5 min固碳量基本相当；未碳化再生微粉制成的人造骨料,经碳化养护后抗压强度为42.7 MPa；经过湿法碳化处理的再生微粉再压制成人造骨料时,碳化后强度相对对照组有所降低,主要是由于碳化反应物减少。碳足迹核算显示,碳化再生微粉人造骨料可以实现碳排放大幅降低。

Abstract:

Recycled micro-powder has excellent carbon sequestration potential, and the wet carbonation method enhances its carbon sequestration performance. In this study, micron bubbles and ultrasonic-assisted methods were used to improve the carbon sequestration efficiency of wet carbonation. Then the recycled micro-powder slurry after carbonation was compressed into artificial aggregate, and a secondary carbonation was further conducted to improve the mechanical strength of artificial aggregate. The CO₂ volumetric method of aluminum film bag was proposed to evaluate the carbon sequestration amount and carbonation degree of recycled micro-powder. Finally, the carbon footprints of this carbonated recycled micro-powder and artificial aggregate are calculated. The results indicate that the wet carbonation method proposed in this study can effectively improve the carbonation efficiency of recycled micro-powder. The use of aluminum film bag for CO₂ volumetric method of the carbon fixation in recycled micro-powder is straghtforward and practical. The carbon sequestration amount of recycled micro-powder in aluminum film bag with 100% CO₂ concentration for 0.5 h is comparable to that of the wet carbonation method proposed in this study for 5 minutes. The compressive strength of the artificial aggregate made of non-carbonated recycled micro-powder is 42.7 MPa after carbonation curing. However, when recycled micro-powder treated with wet carbonation is remolded into artificial aggregates, the post-carbonation strength is relatively lower compared to the control group, mainly due to the reduction of carbonation reactants. Carbon footprint calculation shows that carbonized recycled micro-powder artificial aggregates can achieve a significant reduction in carbon emissions.