Interlaboratory study on rheological properties of cement pastes and reference substances: comparability of measurements performed with different rheometers and measurement geometries

Haist, Michael; Link, Julian; Nicia, David; Leinitz, Sarah; Baumert, Christian; Bronk, Tabea von; Cotardo, Dario; Pirharati, Mahmoud Eslami; Fataei, Shirin; Garrecht, Harald; Gehlen, Christoph; Hauschildt, Inga; Ivanova, Irina; Jesinghausen, Steffen; Klein, Christine A.; Krauss, Hans-W.; Lohaus, Ludger; Lowke, Dirk; Mazanec, Oliver; Pawelczyk, Sebastian; Pott, Ursula; Radebe, Nonkululeko W.; Riedmiller, Joachim Jürgen; Schmid, Hans‐Joachim; Schmidt, Wolfram; Secrieru, Egor; Stephan, Dietmar; Thiedeitz, Mareike; Wilhelm, Manfred; Mechtcherine, Viktor

doi:10.1617/s11527-020-01477-w

Cited by 52 publications

(32 citation statements)

References 30 publications

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“…Converting them to shear stress and shear rate is complex, especially with probes such as the one used in the current study (fishbone). Haist et al [ 31 ] conducted an interlaboratory study for different geometries and recommended conversion factors for absolute value shear stress and shear rate determination based on the affine-translation approach. In the current study, the yield stress and plastic viscosity values were obtained by using these conversion factors.…”

Section: Resultsmentioning

confidence: 99%

Rheology of Alkali-Activated Blended Binder Mixtures

2021

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Alkali-activated cement (AAC) is an alternative cement that has been increasingly studied over the past decades mainly because of its environmental benefits. However, most studies are on heat-cured AACs and are focused on mechanical properties. There is a lack of research on the fresh properties of ambient-cured AAC systems. This study investigates the rheological properties of ambient-temperature-cured alkali-activated blended binder mixtures activated with sodium silicate and sodium hydroxide solutions. The influence of binder amount, alkaline solid to binder ratio (AS/B), sodium silicate to sodium hydroxide solids ratio (SS/SH), and total water content to total solid (from the binding materials) ratio (TW/TS) on the rheological properties are investigated. The effect of borax as an admixture and silica fume as a replacement for fly ash is also investigated. The results showed that both the yield stress and plastic viscosity are mainly affected by the binder content and TW/TS ratio decreasing with the increase of each parameter. The yield stress increased with the increase of the SS/SH ratio. Borax significantly reduced the yield stress, while silica fume’s effect was dependent on its dosage.

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Section: Resultsmentioning

confidence: 99%

Rheology of Alkali-Activated Blended Binder Mixtures

2021

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“…The average torque was calculated from the torque values of the last two seconds for each shear step, which could be assumed as equilibrium state. The shear stress was calculated following the equation given in Figure 3, compare [46]. The dynamic yield stress τ 0,d for each flow curve was calculated following the Bingham regression for the steady state between applied shear rates γ of 20 s −1 and 60 s −1 .…”

Section: Rheological Measurementsmentioning

confidence: 99%

Effect of Pre-Shear on Agglomeration and Rheological Parameters of Cement Paste

et al. 2020

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Cementitious pastes are multiphase suspensions that are rheologically characterized by viscosity and yield stress. They tend to flocculate during rest due to attractive interparticle forces, and desagglomerate when shear is induced. The shear history, e.g., mixing energy and time, determines the apparent state of flocculation and accordingly the particle size distribution of the cement in the suspension, which itself affects suspension’s plastic viscosity and yield stress. Thus, it is crucial to understand the effect of the mixing procedure of cementitious suspensions before starting rheological measurements. However, the measurement of the in-situ particle agglomeration status is difficult, due to rapidly changing particle network structuration. The focused beam reflectance measurement (FBRM) technique offers an opportunity for the in-situ investigation of the chord length distribution. This enables to detect the state of flocculation of the particles during shear. Cementitious pastes differing in their solid fraction and superplasticizer content were analyzed after various pre-shear histories, i.e., mixing times. Yield stress and viscosity were measured in a parallel-plate-rheometer and related to in-situ measurements of the chord length distribution with the FBRM-probe to characterize the agglomeration status. With increasing mixing time agglomerates were increasingly broken up in dependence of pre-shear: After 300 s of pre-shear the agglomerate sizes decreased by 10 µm to 15 µm compared to a 30 s pre-shear. At the same time dynamic yield stress and viscosity decreased up to 30% until a state of equilibrium was almost reached. The investigations show a correlation between mean chord length and the corresponding rheological parameters affected by the duration of pre-shear.

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“…The rheological measurements on the cement suspensions were performed using a Thermo Scientific™ HAAKE™ MARS™ 60 Rheometer (Karlsruhe, Germany) equipped with a circulation thermostat, a cylindrical measuring cell for building materials and a specially designed measuring paddle. Details on the applied rheometer can be found in [16,28].…”

Section: Rheological Measurements and Data Evaluationmentioning

confidence: 99%

The Influence of Bleeding of Cement Suspensions on Their Rheological Properties

2020

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Flowable concretes tend to segregate. The risk of segregation is particularly high when the concrete is vibrated during the compaction process. A well-known segregation phenomenon is the so-called “bleeding”. This is a rise of water to the surface of the freshly poured concrete due to the difference in density between the mixing water and the concrete’s denser solid components (aggregates, cement and additives). This type of segregation occurs particularly within the paste. The focus of this paper is, therefore, on the sedimentation behavior at the microscale of concrete and especially on the influence of this process on rheological properties of the cement paste. In addition to common bleeding tests of cement suspensions using standing cylinders, rheometric measurements were performed on the suspensions during the bleeding process. A measuring procedure was developed for the rheometric measurements of the sedimenting cement suspensions. The rheological properties of the investigated cement suspensions were determined at four specific measuring times and at four specific measuring heights (i.e., positions) each. With this method it could be shown that the cement suspensions are not homogeneous over their height and that bleeding has a great influence on the rheological properties of cement suspension.

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Interlaboratory study on rheological properties of cement pastes and reference substances: comparability of measurements performed with different rheometers and measurement geometries

Cited by 52 publications

References 30 publications

Rheology of Alkali-Activated Blended Binder Mixtures

Rheology of Alkali-Activated Blended Binder Mixtures

Effect of Pre-Shear on Agglomeration and Rheological Parameters of Cement Paste

The Influence of Bleeding of Cement Suspensions on Their Rheological Properties

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