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Clay Nanosize Effects on the Rheological Behavior at Various Elevated Temperatures and Mechanical Properties of the Cement Paste: Experimental and Modeling
Iranian Journal of Science and Technology, Transactions of Civil Engineering ( IF 1.7 ) Pub Date : 2021-03-01 , DOI: 10.1007/s40996-021-00604-z
Ahmed Mohammed , Serwan Rafiq , Kawan Ghafor , Wael Emad , Riyadh Noaman , Ahmed Y. Qasim , Warzer Qadir

This study evaluated and quantified the effect of nanoclay (NC) as an additive for the cement paste. Experimental tests and modeling and microstructure tests were conducted to predict the cement paste's flow properties such as yield stress, shear strength (shear stress limit), viscosity, and compression stress at the failure of cement after hardened. Two different rheological models were used to predict the rheological properties of the cement paste, and based on the statistical assessments, the Vipulanandan rheological model predicted the shear stress versus shear strain rate better than the P-E model. The nanoclay (NC)-modified cement paste was measured at 0.35 and 0.45 of water/cement ratios, and the temperature varied between 25 and 75 °C. NC has improved ultimate shear stress and yield stress, respectively, by 22.5%–54.4% and 26.3%–203% based on the NC content, water/cement ratio (w/c), and temperature. TGA tests have shown that 1% of nanoclay reduces the cement weight loss at 800 °C by 74% as a result of interaction with cement paste. Among the used approaches and based on the tested dataset, the model made according to the NLR models is the most reliable model to predict flow properties and compression strength of the cement and it is performing better than the ANN model according to statistical assessment such as coefficient of correlation (R) and root mean square error (RMSE).



中文翻译:

粘土纳米尺寸对水泥浆在不同高温下的流变行为和力学性能的影响:实验和建模

这项研究评估并量化了纳米粘土(NC)作为水泥浆添加剂的效果。进行了实验测试,建模和微观结构测试,以预测水泥浆在硬化后的破坏时的流动特性,例如屈服应力,剪切强度(剪切应力极限),粘度和压缩应力。使用两种不同的流变模型预测水泥浆的流变特性,基于统计评估,Vipulanandan流变模型比PE模型更好地预测了剪切应力与剪切应变率。在水/水泥比为0.35和0.45的情况下测量了纳米粘土(NC)改性的水泥浆,温度在25到75°C之间变化。NC分别将极限剪切应力和屈服应力提高了22.5%–54.4%和26。基于NC含量,水灰比(w / c)和温度的3%–203%。TGA测试表明,由于与水泥浆相互作用,1%的纳米粘土可将800°C时的水泥失重减少74%。在所使用的方法中,并基于测试的数据集,根据NLR模型制作的模型是预测水泥流动特性和抗压强度的最可靠模型,并且根据统计评估(例如系数),其性能优于ANN模型。相关性(R)和均方根误差(RMSE)的关系。

更新日期:2021-03-01
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