<p>This study aimed to predict the yield stress and plastic viscosity of Superabsorbent Polymer (SAP)-modified cement pastes using the Yield stress mODEL (YODEL) and the Krieger-Dougherty (K-D) equation. Predictions were made for cement pastes with SAP dosages of 0.2–0.5% (by weight of cement) and water-to-cement (w/c) ratios of 0.4–0.6, over 5–35 minutes, and were compared with experimental data. In the YODEL model, the percolation threshold (<InlineEquation ID="IEq1"> <EquationSource Format="MATHML"><math> <msub> <mi>ϕ</mi> <mn>0</mn> </msub> </math></EquationSource> <EquationSource Format="TEX">$\phi _{0}$</EquationSource> </InlineEquation>) and surface-to-surface separation distance (H) were fitted. The <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math> <msub> <mi>ϕ</mi> <mn>0</mn> </msub> </math></EquationSource> <EquationSource Format="TEX">$\phi _{0}$</EquationSource> </InlineEquation> values (0.20–0.27) decreased over time, indicating paste stiffening and reduced percolation. The values of H (1.5–3 nm) declined with higher SAP dosages and over time due to water absorption and hydration, leading to increased flocculation and stiffening. In the K-D model, intrinsic viscosity [<InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math> <mi>η</mi> </math></EquationSource> <EquationSource Format="TEX">$\eta $</EquationSource> </InlineEquation>] was adjusted; [<InlineEquation ID="IEq4"> <EquationSource Format="MATHML"><math> <mi>η</mi> </math></EquationSource> <EquationSource Format="TEX">$\eta $</EquationSource> </InlineEquation>] increased with higher SAP dosages, greater w/c ratios, and time, consistent with thickening caused by SAP water uptake and hydration. For w/c = 0.4, predictions agreed with experiments from 5–15 min, with larger deviations occurring later. For w/c = 0.5 and 0.6, predictions aligned from 5–20 min, with slight overestimations and underestimations afterward. The K-D equation generally provided close agreement with experimental viscosities, showing only minor deviations. Overall, YODEL effectively captured early-age yield stress behavior, while the K-D equation successfully predicted viscosity trends, demonstrating the combined potential of these models for describing the rheology of SAP-modified cement paste.</p>

Prediction of yield stress and plastic viscosity of superabsorbent polymer modified cement pastes: YODEL model and Krieger-Dougherty equation

期刊论文
发表日期：

2025年11月5日

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Nilam Adsul,
Su-Tae Kang

摘要

This study aimed to predict the yield stress and plastic viscosity of Superabsorbent Polymer (SAP)-modified cement pastes using the Yield stress mODEL (YODEL) and the Krieger-Dougherty (K-D) equation. Predictions were made for cement pastes with SAP dosages of 0.2–0.5% (by weight of cement) and water-to-cement (w/c) ratios of 0.4–0.6, over 5–35 minutes, and were compared with experimental data. In the YODEL model, the percolation threshold ( $ϕ_{0}$ $\phi _{0}$ ) and surface-to-surface separation distance (H) were fitted. The $ϕ_{0}$ $\phi _{0}$ values (0.20–0.27) decreased over time, indicating paste stiffening and reduced percolation. The values of H (1.5–3 nm) declined with higher SAP dosages and over time due to water absorption and hydration, leading to increased flocculation and stiffening. In the K-D model, intrinsic viscosity [ $η$ $\eta $ ] was adjusted; [ $η$ $\eta $ ] increased with higher SAP dosages, greater w/c ratios, and time, consistent with thickening caused by SAP water uptake and hydration. For w/c = 0.4, predictions agreed with experiments from 5–15 min, with larger deviations occurring later. For w/c = 0.5 and 0.6, predictions aligned from 5–20 min, with slight overestimations and underestimations afterward. The K-D equation generally provided close agreement with experimental viscosities, showing only minor deviations. Overall, YODEL effectively captured early-age yield stress behavior, while the K-D equation successfully predicted viscosity trends, demonstrating the combined potential of these models for describing the rheology of SAP-modified cement paste.