Re-Use and Volume Reduction of Scabbled Contaminated Concrete Arising from Nuclear Decommissioning
Re-Use and Volume Reduction of Scabbled Contaminated Concrete Arising from Nuclear Decommissioning
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发表时间：
2018-12
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通讯作者：
T. Lord
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作者：
T. Lord
在核设施退役期间，受放射性污染的混凝土从本体中粗化，产生中间水平废物（ILW）流，需要在储存和最终处置之前封装在水泥基质中。一个共同处置的选择进行了调查，使用粗糙的材料作为一个水泥替代封装灌浆，固定其他废物流，消除了直接处置的需要，并增加了整体废物容器的体积比。由于封装浆液对性能有严格的要求，因此研究了包裹性粗骨料对封装浆液性能的影响。在这项研究中，四个模拟scabbling合成，使用CEM I和CEM II的混凝土，在他们被粉碎和地面，一半的地面材料从每个经历加速碳化，作为scabbling的深度是在相同的范围内的碳化深度在老化混凝土。然后，将该硬化剂用于替换封装灌浆混合物中预定百分比的粘合剂含量，其中水泥与矿渣的比例（OPC：BFS）保持在1：3，并研究其对水化和工程性质的影响。发现粗糙度影响灌浆的水化作用，高于单独的填料作用，存在剩余的无水材料和用于矿渣活化的氢氧化钙，影响整体水化作用。混合物与10%的夹杂物显示出类似的整体水化和工程性能的参考灌浆，而超过10%的夹杂物，这些性能受到显着影响。碳酸化的粗骨料对水化和工程性能的影响不同于非碳酸化的粗骨料，碳酸钙的存在产生了三元混合水泥，并由此改善了工程性能。总体而言，人们发现，用高达10%的回收粗骨料替代粘合剂是可能的，灌浆性能保持在规范限制范围内。超过10%的替代水平是不可行的。
During decommissioning of nuclear sites, radioactively contaminated concrete is scabbled from the bulk, creating an intermediate level waste (ILW) stream, requiring encapsulation in a cementitious matrix prior to storage and eventual disposal. A co-disposal option was investigated, using the scabbled material as a cementitious replacement within encapsulation grouts, to immobilise other waste streams, removing the need for direct disposal and increasing the overall waste to container volume ratio. Encapsulation grouts have strict specifications on performance, and so the effect of the inclusion of scabblings on the grout was investigated. In this study, four simulant scabblings were synthesised, using a CEM I and CEM II based concrete, before they were crushed and ground, with half of the ground material from each undergoing accelerated carbonation, as the depth of scabbling is in the same range as the depth of carbonation in aged concrete. The scabblings were then used to replace predetermined percentages of the binder content in encapsulation grout mixes, with the cement to slag ratio (OPC:BFS) maintained at 1:3, and the effect on the hydration and engineering properties investigated. The scabblings were found to affect the hydration of the grout above that of solely the filler effect, with the presence of remaining anhydrous material, and calcium hydroxide for slag activation, affecting the overall hydration. Mixes with 10% inclusion showed similar overall hydration and engineering properties to a reference grout, while beyond 10% inclusion these properties were significantly affected. The carbonated scabblings were found to affect the hydration and engineering performance differently to the non-carbonated, with the presence of calcium carbonate creating a ternary blended cement, and the resultant improvement in engineering properties was found. Overall, it was found that replacement of the binder with up to 10% recycled scabblings is possible, with the grout properties remaining within the specification limits. Replacement levels above 10% are not feasible.