Understanding Cement-Superplasticiser Interactions in Geopolymer Encapsulants for Safe Disposal of Radioactive Waste

了解地质聚合物封装剂中水泥与超塑化剂的相互作用，以安全处置放射性废物

• 批准号: 2735166
• 金额: --
• 依托单位: University of Sheffield
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2735166
• 关键词: Understanding; Cement; Superplasticiser; Interactions; Geopolymer

In the UK, over 150,000m3 of radioactive waste (enough to fill 60 Olympic size swimming pools) has been produced to date. Most of this radioactive waste needs conditioning by encapsulating it in cement to prevent release to the biosphere.Geopolymer cements are ideally suited for this, providing low viscosity, increased tolerance to problematic wastes, and lower leach rates of fission products than other encapsulants. Geopolymer cements also have significantly lower CO2 emissions associated with their production compared to traditional Portland cement, reducing these by as much as 90%, and are critical in helping to reach Net Zero 2050. Superplasticising dispersants can further improve flow characteristics at a given water content, and reduce the requirement for tight specifications on cement powders needed at encapsulation plants. However, superplasticiser behaviour in geopolymers differs significantly from that in common Portland cement encapsulants, due to extensive differences between aqueous and solid-state chemistry in each case. There is little information on what parameters are critical to reliable application.Chemical differences between geopolymers and Portland cement encapsulants lead to different superplasticiser effects (exacerbated by variability in powder physical/chemical characteristics), and little is known about which superplasticisers are most suitable for geopolymers. It is essential that we understand the fundamental cement-superplasticiser interactions, and effect on geopolymer encapsulant performance, so that robust specifications can be developed, and encapsulant properties and performance can be predicted.This PhD examines interactions between organic superplasticisers and inorganic cement particles in geopolymer encapsulants, benchmarked against common Portland cement-based encapsulants. It adopts a new in-situ characterisation approach (including surface-specific techniques, spectroscopic and microstructural characterisation) to investigate mechanisms and kinetics of organic-inorganic interactions, and effects on performance.We will elucidate the fundamental processes controlling dispersion, fluidisation and reaction of these cements, and design, produce and test novel encapsulant formulations with enhanced performance.

迄今为止，英国已产生超过 150,000 立方米的放射性废物（足以填满 60 个奥林匹克规模的游泳池）。大多数放射性废物需要通过将其封装在水泥中来进行调节，以防止释放到生物圈中。地质聚合物水泥非常适合这种情况，与其他封装剂相比，它具有低粘度、对有问题的废物的更高的耐受性以及较低的裂变产物浸出率。与传统波特兰水泥相比，地聚合物水泥在生产过程中的二氧化碳排放量也显着降低，减少多达 90%，对于帮助实现 2050 年净零排放至关重要。超塑化分散剂可以进一步改善给定含水量下的流动特性，并降低封装厂所需水泥粉末的严格规格要求。然而，由于水性和固态化学之间的巨大差异，地质聚合物中的超塑化剂行为与普通波特兰水泥封装剂中的行为显着不同。关于哪些参数对可靠应用至关重要的信息很少。地质聚合物和波特兰水泥密封剂之间的化学差异导致不同的超塑化剂效果（粉末物理/化学特性的变化加剧），并且对于哪种超塑化剂最适合地质聚合物知之甚少。我们必须了解水泥-高效减水剂的基本相互作用以及对地质聚合物密封剂性能的影响，以便开发可靠的规格，并预测密封剂的性能和性能。本博士研究了地质聚合物密封剂中有机高效减水剂和无机水泥颗粒之间的相互作用，以常见的波特兰水泥基密封剂为基准。它采用新的原位表征方法（包括表面特定技术、光谱和微观结构表征）来研究有机-无机相互作用的机制和动力学以及对性能的影响。我们将阐明控制这些水泥的分散、流化和反应的基本过程，并设计、生产和测试具有增强性能的新型封装剂配方。