Different methods have been proposed in the literature to determine the yield stress of cement grouts. These methods may present wide differences especially for thixotropic materials such as cement pastes. In this paper, different mixtures of water–cement–superplasticizer were studied for various w/c ratios and superplasticizer dosages. From shear tests of the mixtures in a rheometer, yield stress was determined in different ways: by identification on the experimental flow curve or by modelling flow curve through different rheological models. The conventional rheological models as Bingham model and Herschel–Bulkley model are not in agreement in the majority of the cases studied especially at low shear rates where thixotropy can be observed. In order to enhance the modelling in this area and allows to accurately determine the yield stress, we compared the results obtained through the conventional rheological models to that obtained by a thixotropy model. From the obtained results, it turns out that the latter allows to better predict the behaviour of thixotropic cement grouts and their yield stress.

中文翻译：

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不同方法测定水泥浆体屈服应力的比较研究

文献中提出了不同的方法来确定水泥浆的屈服应力。这些方法可能存在很大差异，尤其是对于水泥浆等触变材料。在本文中，研究了不同水灰比和减水剂用量的水-水泥-减水剂的不同混合物。从流变仪中混合物的剪切试验中，屈服应力以不同方式确定：通过在实验流动曲线上识别或通过不同流变模型对流动曲线进行建模。Bingham 模型和 Herschel-Bulkley 模型等常规流变模型在研究的大多数情况下不一致，尤其是在可以观察到触变性的低剪切速率下。为了增强该区域的建模并允许准确确定屈服应力，我们将通过传统流变模型获得的结果与通过触变模型获得的结果进行了比较。从获得的结果来看，后者可以更好地预测触变水泥浆的行为及其屈服应力。