Clay Nanosize Effects on the Rheological Behavior at Various Elevated Temperatures and Mechanical Properties of the Cement Paste: Experimental and Modeling

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 degrees 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 degrees 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).

Automated summary

The study found that nanoclay (NC) has a significant impact on the rheological properties and compressive strength of cement paste, improving shear stress and yield stress. Experimental results show that NC-modified cement paste exhibits different performance under different water/cement ratios and temperatures.