Increasing efficiency of carbon dioxide Sequestration through high temperature carbonation of cement-based materials

摘要

The increasing global carbon dioxide concentration has received significant public attention in recent decades, with various sequestration methods being proposed by researchers all around the world. The enormous amount of generated cement-based building materials, such as waste concrete aggregate, particularly exhibits a great carbon dioxide fix potential through the carbonation process. However, the slow reaction speed in a normal environment prohibits its further application. On the other hand, exhaust carbon dioxide emitted from a cement factory is usually in a broad temperature range. Therefore, high temperature carbonation is proposed to accelerate the carbon dioxide sequestration speed in this study. The carbonation performance and carbon dioxide uptake rate of cement paste blocks and powder were evaluated in a broad temperature range (20 degrees C-300 degrees C), demonstrating that carbonation speed was greatly affected by temperature, with optimum carbonation temperature appearing at around 100 degrees C, at which cement paste samples could achieve the fastest carbonation speed at a rate of 16.4%/h in the first 1 h compare to 2.4%/h at normal temperature. In addition, the inner liquid water content of samples was another great influential factor which is related closely to the calcium carbonate generation rate from different hydrate substances, and adding liquid water into samples at appropriate time intervals could enhance carbonation reaction effectively, with the maximum improvement of 34.1%. Consequently, it was found that an improvement could be achieved at 100 degrees C in comparison with normal temperature, with a further increase of 721% being attained by adding liquid water every 20 min to 2mm thickness cement paste blocks. (C) 2019 Elsevier Ltd. All rights reserved.