Durability of Mg-Si-hydrate-based cements from brucite

硅酸镁水合物水泥是一种新型水泥，其利用当使氧化镁与可溶性二氧化硅源反应以形成硅酸镁的大部分无定形水合凝胶（M-S-H凝胶）时产生的强度。它是减少塞拉菲尔德燃料池废物量的理想选择，因为这些池中的固体主要是氢氧化镁，在适当的情况下，氢氧化镁也可以转化为M-S-H凝胶，即废物将有效地成为固定废物的粘合剂的主要成分。然而，虽然水合硅酸镁凝胶作为硫酸镁侵蚀普通波特兰水泥的副产物已经被知道了很长时间，但是关于其耐久性和长期行为的了解少得多。因此，该项目将探讨（i）如何对污泥进行预处理，以使其能够产生合适的废物形式，因为过多的水会大大降低其机械性能，以及（ii）耐久性，即此类水泥的长期稳定性，以确定这种新型水泥是否可能保持稳定，特别是在废物的初始地上储存期间。

Magnesium silicate hydrate cements are a new type of cement that exploits the strength generated when magnesium oxide is made to react with a soluble silica source to form a mostly amorphous hydrated gel of magnesium silicate (M-S-H gel). It is a perfect candidate for reducing the volume of waste from the fuel ponds in Sellafield as the solids in those ponds are mostly magnesium hydroxide, which can also be converted in M-S-H gel under the right circumstances, i.e. the waste would effectively be a large component of the binder in which it is immobilised. However, while hydrated magnesium silicate gels have been known for a long time as a by-product of magnesium sulphate attack on normal Portland cement, much less is known about its durability and long term behaviour. Therefore the project would explore (i) how sludges should be pre-treated to enable the production of a suitable wasteform as too much water will reduce the mechanical properties substantially and (ii) the durability, i.e. long term stability of such cements, to ascertain whether this new type of cement is likely to remain stable especially during the initial above ground storage of the waste.