Influence of adsorbed and nonadsorbed polymer additives on the viscosity of magnesium oxide suspensions

Abstract

Adsorbed polymer additives have been employed to reduce water content and improve cement workability through lowering viscosity, but the influence of over‐dosage and the presence of nonadsorbed chains have yet to be fully understood. Model magnesium oxide (MgO) suspensions were used to investigate the potential processing effect of “free” chain concentration on cementitious mixtures. The rheological impact of the free chains was measured through incorporation of nonadsorbing poly(ethylene glycol) (PEG) to suspensions stabilized with an adsorbed comb‐polymer superplasticizer. Analyses of the rheological data, that showed viscosity‐increases and viscosity‐reduction due to free PEG concentrations revealed a transition from depletion flocculation to depletion stabilization that contributed to the flow properties of the suspensions. The viscosity‐reduction observed for high concentrations of free chains may be useful for improved mixing of cements with free polymer in addition to the adsorbed polycarboxylate ether‐based superplasticizer. Additionally, the influence of free PEG on the macroscale flow behavior was also examined through local velocity measurements under shear. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45696.

Interplay of Anionic Functionality in Polymer-Grafted Lignin Superplasticizers for Portland Cement

“…While the dispersant design has focused on the role of adsorbed polymer in mediating particle–particle interactions, the machine learning model that led to the design of LSPMAA incorporated solution forces in addition to particle forces . Indeed, experimental studies have demonstrated that intrinsic viscosity is important in determining the yield stress in concentrated suspensions, , suggesting that it needs to be considered as a design principle on par with effects on particle interactions.…”

MgO-based cements – Current status and opportunities

“…superplasticizers based on polycarboxylate-ether or naphthalene sulfonate, seem to work with MgO-based cements as well. However generally quite high dosages are needed for these cements e.g., MOC cement [120], MOS cement [121], MgO-based suspensions and paste [122][123][124], and MC cement [65]. Despite the high dosages, the retarding effect seems to be less than in the case of PC-based systems, and the addition of a retarder may still be necessary i.e.…”

Molecular Engineering of Superplasticizers for Metakaolin‐Portland Cement Blends with Hierarchical Machine Learning

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