Abstract The influence of sewage sludge ash (SSA) on the hydration of Portland cement (OPC) was investigated in this study. Blending OPC with SSA was found to influence the kinetic of hydration, notably the alite dissolution. This retardation effect has been attributed to the presence of the orthophosphate ions (PO43−). However, SSA releases only a small fraction of PO43− into solution, which is deemed insufficient to precipitate calcium phosphates compounds on noticeable levels at least. On the other hand, an enhancement of the engineering-scale properties (i.e. mechanical and durability) and portlandite consumption are observed when SSA is used. This is explained by the formation of AFm phases, which leads to changes in the total volume of the solid and thus the properties of the systems. These experimental results were confirmed by thermodynamic modelling, showing that the additional alumina released by SSA results in the formation of higher amount of AFt and AFm phases.

中文翻译：

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污水污泥灰分替代水泥的水化机理

摘要 本研究研究了污水污泥灰分（SSA）对硅酸盐水泥（OPC）水化的影响。发现将 OPC 与 SSA 混合会影响水合动力学，特别是阿利特溶解。这种延迟效应归因于正磷酸根离子 (PO43-) 的存在。然而，SSA 仅将一小部分 PO43- 释放到溶液中，这被认为至少不足以使磷酸钙化合物以明显的水平沉淀。另一方面，当使用 SSA 时，观察到工程规模特性（即机械和耐久性）和硅酸盐消耗的增强。这可以通过 AFm 相的形成来解释，这会导致固体总体积发生变化，从而导致系统性质发生变化。