Abstract The effects of gamma irradiation on the properties of concrete or cement composites have been investigated by several authors. However, the behaviour of composites immobilizing radioactive evaporator concentrates may be significantly affected by the altered chemistry of the matrix material. A newly proposed binder intended for the development of a composite immobilizing evaporator concentrates was investigated in terms of changes in its’ mechanical properties due to gamma irradiation. Three kinds of cement pastes – a reference Portland cement paste (PC), a proposed binder as a mix of cements (NP) and a mixture “NP” containing a model evaporator concentrate (NP_C) - were irradiated by gamma source Co-60 in two subsequent experiments differing in conditions – non-sealed (on air) and sealed (in a glass box). Surface cracks appeared on the NP and NP-C samples after the first irradiation experiment, i.e. in non-sealed conditions, due to drying effects supported by high ventilation in the irradiation chamber. In sealed conditions, some smaller surface cracks also appeared probably due to radiolysis of water present in the material, however they did not have any effects on the integrity of the internal structure of the pastes observed by non-destructive measurements. Compressive strength was enhanced by irradiation in all cases, only flexural strength decreased due to the presence of surface cracks. It should be noted that surface cracks appeared also on non-irradiated NP_C samples when left on air to dry. Therefore, further development of the cement composites will be focused on the elimination of any volume changes due to drying.

中文翻译：

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用于固定蒸发器浓缩物的辐照水泥浆的机械性能

摘要 几位作者已经研究了伽马辐射对混凝土或水泥复合材料性能的影响。然而，固定放射性蒸发器浓缩物的复合材料的行为可能会受到基质材料化学变化的显着影响。研究了一种新提出的用于开发复合固定蒸发器浓缩物的粘合剂，研究了其机械性能由于伽马辐射而发生的变化。三种水泥浆——参考波特兰水泥浆 (PC)、建议的作为水泥混合物 (NP) 的粘合剂和含有模型蒸发器浓缩物 (NP_C) 的混合物“NP”——被伽马源 Co-60 辐照随后的两个实验条件不同——非密封（在空气中）和密封（在玻璃盒中）。在第一次辐照实验后，即在非密封条件下，NP 和 NP-C 样品上出现表面裂纹，这是由于辐照室中高通风支持的干燥效应。在密封条件下，也可能由于材料中存在的水的辐射分解而出现一些较小的表面裂纹，但它们对无损测量观察到的糊状物内部结构的完整性没有任何影响。在所有情况下，抗压强度都通过辐照增强，只有弯曲强度由于表面裂纹的存在而降低。应该注意的是，当置于空气中干燥时，未辐照的 NP_C 样品上也会出现表面裂纹。因此，水泥复合材料的进一步开发将集中在消除因干燥而引起的任何体积变化上。