Abstract Understanding the role of retarder on the chemical nature and molecular architecture of hydrating cement paste is essential for engineering oil well cements with additives. Here, synchrotron X-ray and total neutron scattering with pair distribution function (PDF) analysis were performed in combination with calorimetry and nuclear magnetic resonance (NMR) to examine the retarder effect in hydrating tri-calcium silicate (C3S) and Class G oil well cement paste. Primarily, the retarder, Diethylenetriamine pentamethylene phosphonic acid (DTPMP) influenced the hydration by affecting the Ca-O and Ca-Si pair correlation providing evidence of calcium playing a predominant role in the retardation process. Secondary effects related to Calcium-Silicate-Hydrate (C-S-H) nuclei poisoning influencing the suppression of calcium hydroxide precipitation were observed. These findings provide insights into the retardation mechanism of hydrating cement paste influenced by calcium depletion when subjected to phosphonate retarders.

中文翻译：

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使用原位中子/X 射线对分布函数分析研究水化油井水泥的缓凝剂效应

摘要 了解缓凝剂对水化水泥浆的化学性质和分子结构的作用对于使用添加剂的油井水泥工程至关重要。在这里，同步加速器 X 射线和具有对分布函数 (PDF) 分析的总中子散射与量热法和核磁共振 (NMR) 相结合，以检查在水合硅酸三钙 (C3S) 和 G 类油井中的阻滞效应水泥浆。首先，缓凝剂二亚乙基三胺五亚甲基膦酸 (DTPMP) 通过影响 Ca-O 和 Ca-Si 对相关性来影响水合作用，这提供了钙在缓凝过程中起主要作用的证据。观察到与影响氢氧化钙沉淀抑制的硅酸钙 (CSH) 核中毒相关的次要效应。这些发现提供了对受膦酸盐缓凝剂影响时钙耗竭影响的水化水泥浆的缓凝机制的见解。