Impacts of sulphates on rheological property and hydration performance of cement paste in the function of polycarboxylate superplasticizer

He, Yan; Zhang, Xiong; Liu, Shuhua; Hooton, RD; Ji, Tao; Kong, Yaning

doi:10.1016/j.conbuildmat.2020.119428

Cited by 31 publications

(14 citation statements)

References 55 publications

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“…Figure 7 presents the XRD results obtained for different ages. Portlandite is the main hydration product of cement, and calcium silicate is the unhydrated substance [23].…”

Section: Compressive Strengthmentioning

confidence: 99%

Effects of Adding Neutralized Red Mud on the Hydration Properties of Cement Paste

Kang

Hye-Ju

Lee³

2020

Materials

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Red mud is a highly alkaline waste by-product of the aluminum industry. Although recycling of red mud is being actively researched, a feasible technological solution has not been found yet. In this study, we propose that neutralization of red mud alkalinity could assist in its use as a construction material. Neutralized red mud (LRM + S; pH 6–8) was prepared by adding sulfuric acid to liquefied red mud (LRM; pH 10–12). After adding LRM and LRM + S to cement paste, the heat of hydration, compressive strength, and hydration products were examined. The experiments revealed that the calorific value of the cement paste with LRM was low, and its peak was delayed, when compared with that of plain cement paste (referred to as Plain), whereas the calorific value of the cement paste with LRM + S was similar to that of Plain. At the age of 28 d, the compressive strength of the cement paste with 10% LRM + S was 99% whereas that with 20% LRM was only 55% of the strength of Plain. Thus, our results help to resolve the issue of strength degradation of cementitious materials observed upon the addition of red mud and enable its reuse as a construction material.

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“…Figure 7 presents the XRD results obtained for different ages. Portlandite is the main hydration product of cement, and calcium silicate is the unhydrated substance [23].…”

Section: Compressive Strengthmentioning

confidence: 99%

Effects of Adding Neutralized Red Mud on the Hydration Properties of Cement Paste

Kang

Hye-Ju

Lee³

2020

Materials

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“…This probably occurs due to the increase in alite hydration and, as a result, in C-S-H formation in the presence of Na 2 SO 4 . Therefore, the cation in sulfate probably influences the optimum sulfate content in Portland cements, as observed by He et al [101] when studying MgSO 4 , CaSO 4 Á2H 2 O, Na 2 SO 4 and K 2 SO 4 . Further investigations are needed to verify and provide more information regarding this process.…”

Section: Physics Chemical and Mineralogic Properties Of The Sulfate Sourcementioning

confidence: 80%

“…At the optimum SO 3 content, C 3 A reacts with the sulfates in solution, forming ettringite, and the superplasticizer admixtures adsorb onto aluminate hydrates and silicates phases, increasing the fluidity of the mixture [132,140]. That said, the superplasticizer effect of PCE decreases with an increase in the content of sulfate added, being most significantly influenced by the alkali sulfates (Na 2 SO 4 and K 2 SO 4 ) when compared to gypsum and MgSO 4 [101,140]. When the content of sulfate in cement paste increases, the amount of sulfate ions in solution increases and is competitively adsorbed onto cement surfaces, thereby reducing the adsorption of PCE and decreasing its superplasticizer effect [49,101].…”

Section: Chemical Admixturesmentioning

confidence: 99%

“…That said, the superplasticizer effect of PCE decreases with an increase in the content of sulfate added, being most significantly influenced by the alkali sulfates (Na 2 SO 4 and K 2 SO 4 ) when compared to gypsum and MgSO 4 [101,140]. When the content of sulfate in cement paste increases, the amount of sulfate ions in solution increases and is competitively adsorbed onto cement surfaces, thereby reducing the adsorption of PCE and decreasing its superplasticizer effect [49,101]. On the other hand, if the soluble sulfate/C 3 A ratio is too low, hydration of C 3 A occurs, resulting in the formation of aluminate hydrates that adsorb the chemical admixtures and form organo-mineral phases, thus reducing the superplasticizer effect of PCE [49,132,140].…”

Section: Chemical Admixturesmentioning

confidence: 99%

“…Typically, increasing the sulfate content of the cement increases the water demand [157], the viscosity [101], and the yield stress [101] of cementitious mixtures. Gypsum is softer than clinker; therefore, when it is interground with clinker it usually shows a higher surface area, which is responsible for the increase in the water demand [157].…”

Section: Effect Of Sulfate Content On Workability and Rheologymentioning

confidence: 99%

See 2 more Smart Citations

Effects of sulfates on the hydration of Portland cement – A review

Neto

Torre

Kirchheim

2021

Construction and Building Materials

113

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Synthesis and characterization of a polycarboxylate superplasticizer modified by sodium hypophosphite

Zhang

Wang

Zhang

et al. 2022

Polymers for Advanced Techs

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A sodium hypophosphite (SHP) modified polycarboxylatesuperplasticizer (P-PCE) was synthesized successfully and the synthesis parameters were optimized through orthogonal experiment. Gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), 31 P magic spinning nuclear magnetic resonance ( 31 P MAS NMR) spectroscopy and elemental analysis measurements were used to characterize the molecular structure of P-PCE. Effects of P-PCE on the dispersing performance of cement paste were systematically investigated via mini slump test. The results showed that P-PCE exhibited superior dispersing performance, more retarding hydration effect and better sulfate and clay tolerance than conventional PCE (C-PCE).Results showed that the maximum flow of cement paste could reach up to 305 mm, while that of the C-PCE was 285 mm.The maximum variation of adsorption of P-PCE was 9% and 15% in the presence of sulfate and clay, whereas that of C-PCE was 15% and 25%, respectively, leading to better sulfate and clay tolerance. These significant advantages could be ascribed to the high anion density and high calcium complexing capacity induced by introducingphosphinate group and phosphonate group into the molecular structure of P-PCE. The as-synthesized P-PCE can be used as a kind of high performance superplasticizer in concrete engineering.

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Impacts of sulphates on rheological property and hydration performance of cement paste in the function of polycarboxylate superplasticizer

Cited by 31 publications

References 55 publications

Effects of Adding Neutralized Red Mud on the Hydration Properties of Cement Paste

Effects of Adding Neutralized Red Mud on the Hydration Properties of Cement Paste

Effects of sulfates on the hydration of Portland cement – A review

Synthesis and characterization of a polycarboxylate superplasticizer modified by sodium hypophosphite

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