The yield stress of cement pastes as obtained by different rheological approaches

Mbasha, Willy; Masalova, Irina; Haldenwang, Rainer; Malkin, Alexander

doi:10.3933/applrheol-25-53517

Cited by 4 publications

(1 citation statement)

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“…Four mixtures were subjected to a slump test, including a control mix (0% CKD) prepared by OPC and copper tailing, where CKD gradually replaced cement with 5, 10, and 15%. The chemical composition, physical properties, and water content affect yield stress [83]. Therefore, this study considered 27% water content for all tested mixtures to evaluate the influence of adding CKD on the flowability and rheological properties of the CPB.…”

Section: Slump Yield Stressmentioning

confidence: 99%

Eco-Sustainable Recycling of Cement Kiln Dust (CKD) and Copper Tailings (CT) in the Cemented Paste Backfill

2023

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Cement global demand shows continued growth and a significant increase in the production volume, which may negatively impact the non-renewable natural resources and the environment, which is incompatible with sustainability goals. Cement kiln dust (CKD) is a primary concern associated with clinker manufacturing as a waste byproduct. Similarly, the mining industry produces copper tailing as unwanted material while beneficiating the ore, creating environmental problems due to difficulty in managing worldwide generated quantities that reach billions of metric tons. This study investigated the beneficial utilization of cement kiln dust and copper tailing as undesirable wastes in industrial applications through underground mines’ cemented paste backfill (CPB). Sixty different mixtures were prepared with three types of CKD collected from various cement manufacturers and were accordingly used with a proportion of 5, 10, and 15% to partially replace ordinary Portland cement (OPC) and pozzolan Portland cement (PPC) binders, represented in hundreds of CPB samples. The hardened specimens were subjected to density, uniaxial compressive strength (UCS), and axial deformation measurements to evaluate the physical and mechanical properties at curing up to 90 days. Meanwhile, X-ray powder diffraction (XRD) was extensively applied to chemically investigate the hydration products of CPB-hardened mixtures. Moreover, we developed a UCS predictive model applying two techniques: multiple variables regression analysis and artificial neural network (ANN). The results showed that the tricalcium silicate (Alite) and dicalcium silicate (Belite) phases form C-S-H upon hydrations and provide high strength in the binary mixtures. Meanwhile, the CKD’s lime saturation factor (LSF) governed the strength value in the ternary mixtures that utilized copper tailings. That makes CKD practical in the CPB mixture when partially replacing the OPC and PPC binders, with a proportion of up to 15%. In addition, the ANN technique’s predictive model exhibited a significant positive correlation with excellent statistical parameters that achieved 0.995, 0.065, and 0.911 for R2, RMSE, and MAE, respectively.

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Section: Slump Yield Stressmentioning

confidence: 99%

Eco-Sustainable Recycling of Cement Kiln Dust (CKD) and Copper Tailings (CT) in the Cemented Paste Backfill

2023

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Comparison between methods for determining the yield stress of cement pastes

Matos

Pilar

Casagrande

et al. 2019

J Braz. Soc. Mech. Sci. Eng.

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The determination of the yield stress (τ 0) of cement-based materials is of great interest for engineering applications, since it accurately describes the flow behavior and assesses empirical properties related to its workability, such as the slump of concretes and the spreading of mortars. In this work, the τ 0 of cement pastes was determined by different methods. Specifically, pastes with three different water/cement ratios and two supplementary cementitious materials in Portland cement replacement were produced. The mini slump of the pastes was measured, and its static τ 0 and dynamic τ 0 were determined by rotational rheometry. In addition, small amplitude oscillatory shear (SAOS) was used to further investigate the rigidification rate of the pastes over time, providing valuable information for the discussion. The results showed that the dynamic τ 0 values provided by the different rheological models showed strong correlations. However, these values had weaker correlations with the static τ 0. The rest period between the finish of the pre-shear and the test run strongly affected the magnitude of the stress overshoot and therefore the static τ 0 value. SAOS indicated that the decrease in the inter-particle distance increased the rigidification rate of the paste within the first minute after mixing, which may affect the mini slump results. Finally, the use of the mini slump as a single test to generally evaluate cement pastes with wide ranges of flowability may not be adequate, in line with the existence of different tests for the evaluation of conventional and self-compacting concretes.

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Hydrodynamic interaction between coaxially rising bubbles in elastoviscoplastic materials: Equal bubbles

Kordalis,

Pema,

Androulakis

et al. 2023

Phys. Rev. Fluids

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The yield stress of cement pastes as obtained by different rheological approaches

Cited by 4 publications

References 0 publications

Eco-Sustainable Recycling of Cement Kiln Dust (CKD) and Copper Tailings (CT) in the Cemented Paste Backfill

Eco-Sustainable Recycling of Cement Kiln Dust (CKD) and Copper Tailings (CT) in the Cemented Paste Backfill

Comparison between methods for determining the yield stress of cement pastes

Hydrodynamic interaction between coaxially rising bubbles in elastoviscoplastic materials: Equal bubbles

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