Recyclability of low-clinker cements using "carbon capture and utilisation"- Roads to a sustainable concrete production

利用“碳捕获和利用”实现低熟料水泥的可回收性——可持续混凝土生产之路

• 批准号: 522218903
• 负责人: Dr.-Ing. Nancy Beuntner
• 金额: --
• 依托单位: Institut für Werkstoffe des Bauwesens
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/522218903?language=en
• 关键词: Recyclability; low; clinker; cements; using

The high consumption of natural resources and the high CO2 emissions caused by the construction sector are the biggest challenges to be overcome in order to achieve climate neutrality. The integration of concrete waste into recycling processes is an essential step to achieve the defined goals. “Carbon capture and utilization” (CCU) offers a promising approach. By carbonating the fines of concrete waste (hardened cement paste) and then using it as a reactive cement substitute, CCU can be part of the solution to both challenges. The use of modern clinker-reduced composite cements is expected to result in significant differences in the chemical and mineralogical composition of the fine fractions of concrete waste that will be produced in the future. However, systematic investigations are still lacking to which extend clinker-reduced cements are suitable for carbonation and subsequent use as a reactive supplementary cementitious materials (SCM). This is the onset of the present research project starts. In the first part, the relationships between chemistry and mineralogy of the cements used and the properties as well as the reactivity of the resulting recycled cement paste (recycSCM) are investigated. For this purpose, modern cements (CEM II/C-M and CEM VI) are artificially produced, hydrated and carbonated. In the following step, the performance of the recycSCM is systematically investigated by applying a hydration model to the first 48 hours and using the activity index according to DIN EN 197-1 after 28 days. The uptake of CO2 during the carbonation of the hardened cement paste and the subsequent use of the recycSCM as a reactive SCM cause a considerable reduction of the clinker content and thus offer a significant CO2 saving potential. This savings potential will be compared to the amount of CO2 emitted during the production of the different types of cement. Thus, the CO2 balance of high and low clinker cements with the addition of the different recycSCMs can be presented in detail and, further on, the ecological footprint for concretes produced using these cements can be predicted exemplarily. In summary, the key parameters reactivity, hydration behavior and performance as well as the ecological efficiency of recycSCMs will be investigated. With the results of the project, recycled fines of future concrete waste in the compositions commonly expected to be used worldwide can be assessed in advance with regard to their contribution as a reactive binder component.

建筑业对自然资源的高消耗和二氧化碳的高排放是实现气候中和需要克服的最大挑战。将混凝土废物纳入回收过程是实现既定目标的重要步骤。“碳捕获和利用”（CCU）提供了一个有前途的方法。通过碳酸化混凝土废料（硬化水泥浆）的细粉，然后将其用作活性水泥替代品，CCU可以成为解决这两个挑战的一部分。使用现代熟料减少复合水泥预计将导致显着差异的化学和矿物组成的细馏分的混凝土废物，将在未来产生的。然而，系统的调查仍然缺乏到何种程度的熟料减少水泥是适合碳酸化和随后使用的反应性辅助胶凝材料（SCM）。这是本研究项目的开端。在第一部分中，化学和矿物学的水泥使用和性能之间的关系，以及所得的再生水泥浆体（CANCSCM）的反应性进行了研究。为此，现代水泥（CEM II/C-M和CEM VI）是人工生产的，水合和碳酸化。在接下来的步骤中，通过将水合模型应用于前48小时并在28天后使用根据DIN EN 197-1的活性指数来系统地研究CMCSCM的性能。在硬化水泥浆的碳酸化过程中CO2的吸收以及随后将Al 2 O3 SCM用作反应性SCM导致熟料含量的显著减少，从而提供显著的CO2节约潜力。将把这种节约潜力与生产不同类型水泥过程中的二氧化碳排放量进行比较。因此，CO2平衡的高和低熟料水泥与不同的添加剂的CO2 SCMs可以详细介绍，并进一步，使用这些水泥生产的混凝土的生态足迹可以预测的例子。综上所述，将研究生物质复合材料的反应性、水化行为和性能以及生态效率等关键参数。通过该项目的结果，可以提前评估未来混凝土废料中的回收细粉作为反应性粘合剂组分的贡献，这些细粉通常预计将在全球范围内使用。