Haselbach Liv M, Ma Shuguo
University of South Carolina, 300 Main Street, Columbia, South Carolina 29208, USA.
Environ Sci Technol. 2008 Jul 15;42(14):5329-34. doi: 10.1021/es800717q.
The concrete industry is a contributor to the global carbon cycle particularly with respect to the contribution of carbon dioxide in the manufacturing of cement (calcination). The reverse reaction of carbonation is known to occur in concrete, but is usually limited to exterior surfaces exposed to carbon dioxide and humidity in the air. As alternate concrete uses expand which have more surface area, such as crushed concrete for recycling, it is important to understand surface adsorption of carbon dioxide and the positive impacts it might have on the carbon cycle. X-ray photoelectron spectroscopy (XPS) is used in this study to evaluate carbon species on hydrated cement mortar surfaces. Initial estimates for carbon absorption in concrete using othertechniques predictthe potential for carbonate species to be a fraction of the calcination stoichiometric equivalent The XPS results indicate that there is a rapid and substantial uptake of carbon dioxide on the surfaces of these mortars, sometimes exceeding the calcination stoichiometric equivalents, indicative of carbon dioxide surface complexation species. On pure calcite, the excess is on the order of 30%. This accelerated carbon dioxide surface adsorption phenomenon may be importantfor determining novel and effective carbon sequestration processes using recycled concrete.
混凝土行业是全球碳循环的一个贡献者，特别是在水泥制造（煅烧）过程中二氧化碳的排放方面。已知混凝土中会发生碳化的逆反应，但通常仅限于暴露在空气中二氧化碳和湿度下的外表面。随着具有更大表面积的替代混凝土用途的扩大，例如用于回收的碎混凝土，了解二氧化碳的表面吸附及其对碳循环可能产生的积极影响非常重要。本研究使用X射线光电子能谱（XPS）来评估水合水泥砂浆表面的碳物种。使用其他技术对混凝土中碳吸收的初步估计预测，碳酸盐物种的潜力仅为煅烧化学计量当量的一小部分。XPS结果表明，这些砂浆表面会快速大量吸收二氧化碳，有时超过煅烧化学计量当量，这表明存在二氧化碳表面络合物。在纯方解石上，过量吸收约为30%。这种加速的二氧化碳表面吸附现象对于确定使用再生混凝土的新型有效碳封存工艺可能很重要。
