Influence of high mixing intensity on rheology, hydration, and microstructure of fresh state cement paste

Han, Di; Ferron, Raissa Douglas

doi:10.1016/j.cemconres.2016.03.004

Cited by 102 publications

(31 citation statements)

References 45 publications

(52 reference statements)

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“…It is widely known that the loss of fluidity of cement pastes may be affected by a number of factors, such as cement hydration, mixing procedure, as well as type, dosage and addition mode of superplasticizers, specifically, those based on Polycarboxylate Ether polymers (PCEs) [1][2][3][4][5][6][7]. The fact that these parameters can act simultaneously makes very challenging to describe flow loss in quantitative terms.…”

Section: Introductionmentioning

confidence: 99%

Relating early hydration, specific surface and flow loss of cement pastes

2019

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Flow loss in superplasticized systems has been mainly explained in qualitative and comparative ways over the past years. This is due to the intrinsic complexity of the underlying mechanism involving a change in the agglomeration degree as a result of cement hydration. The lack of robust and reliable experimental methodologies must have additionally discouraged researchers from attempting to understand the phenomena of flow loss in quantitative terms. Thanks to new analytical methods, it was possible to prove that after the so-called onset point, yield stress increases exponentially with the increase of both heat rate measured by isothermal calorimetry and specific surface. This paper also identifies the existence of a direct proportionality between the increase of heat rate and the increase of specific surface area during the acceleration period, most likely reflecting the nucleation and growth nature at this stage of the cement hydration.

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Section: Introductionmentioning

confidence: 99%

Relating early hydration, specific surface and flow loss of cement pastes

2019

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“…Changes in the PSD could have been expected due to shearing during paste preparation. In fact, using focused beam reflectance measurements, Han and Ferron (2016) observed that the size of weakly linked agglomerates increases at a high mixing speed. However, it should be pointed out that high dilution rates as well as agitation during measurement might hide differences in the dispersion states of the dilution liquids (Williams et al, 1999).…”

Section: Resultsmentioning

confidence: 99%

Influence of triethanolamine on cement pastes at early age of hydration

Jachiet

Azéma

Saoût

et al. 2018

Advances in Cement Research

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Activation is often associated with the favoured hydration of particular cementitious phases, which can be induced by complexation mechanisms. However, the dispersion state of pastes with admixtures may also influence hydration rates. The aim of this paper is to highlight the correlation between mesostructural organisation and chemical reactivity of cement pastes with an additive. The affinity of triethanolamine (TEA), an activator molecule, with cement grains was assessed by measurement of total organic carbon. Moreover, the influence of the amine on the dispersion state, sedimentation kinetics and rheological behaviour was studied. Finally, X-ray diffraction, aluminium nuclear magnetic resonance spectroscopy and isothermal calorimetry were used in order to study the chemical reactivity of cement in the presence of the admixture. The combination of these granular and chemical characterisations helped to understand the mode of action of TEA.

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“…With regard to consistency, it could be stated that cement-lime mortars were more sensitive to changes in the mixing procedure than mortars with APA (Tables 19 and 20). This effect might be due to the possibility of uneven distribution of lime in cement-lime mortars, which could occur at high or very low mixing speeds [79]. The admixture was added to the water and mixed by hand, and then added together with water to the mortar, and, therefore, the mixing speed might not be as crucial to an even distribution of the APA in the mortar.…”

Section: Impact Of Mixing Intensitymentioning

confidence: 99%

Assessment of the Impact of Inaccuracy and Variability of Material and Selected Technological Factors on Physical and Mechanical Properties of Fresh Masonry Mortars and Plasters

et al. 2020

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The article presented the analysis of the impact that various kinds of technological inaccuracies have on the properties of fresh masonry mortars and plasters. Analyzed were the inaccuracies in dosing of mortar components, namely, water, lime, and air-entraining plasticizing admixture (APA) (±10% of mass), and the effect of variable technological conditions, namely, different mixing intensity (fast, slow, normal) and temperature (5 • C, 20 • C, and 35 • C) during first 72 h after mixing. The impact of differences in the properties of cement and aerial (hydrated) lime originating from different manufacturers was also analyzed. The impact of these factors was determined for consistency, density, air content, compressive, and flexural strength. The sensitivity to changes in the analyzed properties was determined by the coefficient of variation. Changes in the dosing of constituents, mixing speed, and temperature adversely affected strength properties. For mortars with APA, these changes exceeded 20% and reached 40%. The greatest impact was evident in the consistency, especially with an excess of APA, where changes ranged from 6% to 80%. The results showed greater resistance of cement-lime mortars to changing selected technological conditions and errors in measuring the amount of ingredients than mortars with air-entraining plasticizing admixture (APA). Materials 2020, 13, 1382 2 of 29 using waste materials, e.g., concrete waste [5], glass waste [6], brick flour [7], granite flour [8], marble powder [9], and others. A significant part of the research is devoted to modifying mortars with various additives to improve their properties while partially replacing fillers and binders with waste materials.For example, Harbi et al.[10] carried out the experimental work focused on the study of the possibility of using kaolin dust as filler in the sand, combined with additions of glass powder, brick waste, and metakaolin in order to improve the mechanical performance of the mortar. Mixtures containing glass powder and/or metakaolin turned out to be better than those containing brick waste. Similar research was carried out by Boukour and Benmalek [11], who analyzed the effect of two wastes: crushed clay brick and tire rubber aggregate in cement mortar reinforced by a resinous latex. Test results indicated a decrease in water absorption and shrinkage of such cement mortar.Atypical addition to mortar, which has been a subject of research, is recycled polyethylene terephthalate (PET) bottles [12]. Test results of this experiment have indicated that higher compressive and flexural strength can be obtained for thusly modified cement mortars. Other atypical additions to the mortar that have been researched are organic agents as vinegar, gram pulse, and frog contaminated water and their influence on mechanical properties and mortar's performance [13]. It has been concluded that organic materials chosen for the study adversely affect the compressive strength of cement mortars, especially after six months.Research has also been carried o...

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Influence of high mixing intensity on rheology, hydration, and microstructure of fresh state cement paste

Cited by 102 publications

References 45 publications

Relating early hydration, specific surface and flow loss of cement pastes

Relating early hydration, specific surface and flow loss of cement pastes

Influence of triethanolamine on cement pastes at early age of hydration

Assessment of the Impact of Inaccuracy and Variability of Material and Selected Technological Factors on Physical and Mechanical Properties of Fresh Masonry Mortars and Plasters

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