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Thixotropy of flowable mortar and concrete is an important property that affects stability and form pressure characteristics. The increase in thixotropy can reduce lateral pressure on formwork systems. On the other hand, low thixotropy or a continuous casting is required to eliminate the formation of weak interface between lifts in multilayer casti...
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Context 1
... PV test (Fig. 2) is based on an existing small-scale test to evaluate in situ shear strength of clay soils. Preliminary tests were conducted to determine a protocol of testing that can reflect the thixotropy characteristics of highly flowable mortar and SCC at rest. At the beginning, the same vane set-up (sciss- ometer) employed for standard soil ...
Context 2
... screw bolt of 4 mm in length and 2 mm in diameter in the middle of the bucket base going from the outer to the inner direction of the bucket. Tighten a 4-mm thick nut to the appeared part of screw bolt inside the bucket. Therefore, 2 mm of the nut thickness is fastened to the bolt, and the other 2 mm is hollow to hold the vane's shaft centered [ Fig. 2 in [19] for more details]. 2. Place the buckets (1-4) on a flat surface with the vanes set in vertical positions with the aid of the nut described in step 1 and a plastic cover with central hole. Care should be taken to keep the buckets in place without disturbance. Position the vane of large dimension at the center of bucket # 1 with ...
Citations
... Lootens et al. (2009) explored the use of cone penetrometers to assess the yield stress in cementitious mixtures and identified a robust correlation between cone penetrometer tests and yield stress, resulting in the establishment of strong analytical relationships between concrete yield stress and cone penetrometer test outcomes. Other studies have also employed cone-shaped penetrometers to determine the shear strength of conventional and printable concrete types (Baz et al., 2021;Khayat et al., 2012;Dressler et al., 2020;Mazhoud et al., 2019). Considering these insights and the failure modes initiated by cone penetrometers, this study applied a cone penetrometer with the developed instrument to induce shear failure mode in printing concrete and gauge the shear strength and its development over time. ...
... The inclined plane (IP) test is described in Chap. 3. The test involves casting concrete in a cylindrical mould resting on a horizontal plate of a given roughness, followed by lifting the mould to allow the concrete to spread [30][31][32]. The static yield stress is determined (τ s−IP ) at different times of rest and can be correlated to similar measurements from a rheometer. ...
... For the concrete-equivalent mortars (CEM) of SCC mixtures, Khayat et al. [32] validated the structural build-up index of the portable vane (PV) test using the static yield stress of the modified Tattersall MK-III rheometer equipped with an eightbladed vane. The PVτ 0rest@15min × PVτ 0rest (t) index from the PV test is correlated to the time-dependent static yield stress of the rheometer [Rheometerτ 0rest (t)], as shown in Eq. (6.54): ...
... Khayat et al. [32] proposed where τ 0,s−IP is the static yield stress measured using the inclined plane test method in Pa, τ 0,s−PV is the static yield stress measured using the portable vane test method in Pa, and USS is the undisturbed slump spread in mm. ...
Several empirical test methods used to measure the workability of cement-based materials under field conditions can be employed to evaluate the fundamental rheological properties of these materials. This chapter summarized some of the analytical solutions of different workability test methods for concrete and mortar from the rheological basis. Many of the relationships between the various workability parameters of concrete and mortar determined using empirical tests and their corresponding rheological properties, namely yield stress, plastic viscosity, and thixotropy are evaluated. Limitations of the applicability of the various empirical methods are highlighted to avoid erroneous estimates of rheological characteristics. Established relations between flow properties of 3D printing mortar measured by empirical squeeze and penetration tests and the rheological characteristics are also presented. Other test methods for monitoring the output of concrete mixing trucks, including the imposed load and hydraulic pressure, and the correlations between the rheological performance are discussed for the application of in-drum measurement systems.
... It is important to stress that structural build-up at rest cannot be confused with workability loss, which defines the global strengthening of the cement-based materials even under continuous shearing (e.g., in a concrete mixing truck) [3,19]. Various workability test methods can be used to evaluate the rate of structural build-up at rest when samples are maintained at rest [14,20,21]. ...
... The determination of the structural build-up rate is based on the measurement of the static yield stress of the material and its variation with resting time. This can be done on different samples using invasive tests [20,37], such as the portable vane test or undisturbed slump flow test (for SCC), or non-invasive tests, such as the plate test that allows continuous assessment of the static yield stress on the same test sample [38]. Other types of non-destructive tests, such as ultrasonic measurement can be employed to assess the increase in static yield stress [39]. ...
This paper presents the results of a round-robin testing program undertaken by RILEM TC-266-Measuring Rheological Properties of Cement-Based Materials in May 2018 at the Université d’Artois in Bethune, France. Seven types of rheometers were compared; they consisted of four ICAR rheometers, Viskomat XL rheometer, eBT-V rheometer, Sliding Pipe Rheometer (SLIPER), RheoCAD rheometer, and 4SCC rheometer, as well as the plate test. This paper discusses the results of the evolution of the static yield stress at rest of three mortar and five concrete mixtures that were determined using two ICAR rheometers, Viskomat XL, and eBT-V rheometers, as well as the plate test. For the measurements carried out with rheometers, three different structural build-up indices (i.e., structural build-up rate, critical time, and coupled effects of initial static yield stress and rate of structural build-up) were determined. The indices were established using: (i) two static yield stress values measured after 10 and 40 min of rest; and (ii) two static yield stress values measured after 10 and 40 min of rest plus the initial dynamic yield stress (no rest and obtained from the flow curves). The paper discusses the test results and highlights inaccuracies that could be encountered in determining the static yield stress. Test results indicate that the ICAR rheometers and the selected thixotropic indices can provide similar results, and that the spread of results obtained from different rheometers can be considerably reduced when using three yield stress values to calculate the rate of the static yield stress at rest. In order to enhance the accuracy of measurements, it is recommended to increase the number of measurements of the yield stress to at least three points over one hour after mixing.
... Therefore, this test may not fully represent the real structural build-up of the concrete. Another option is using undisturbed slump flow tests as proposed in (Khayat et al., 2012), where all the cones are filled immediately after the material mixing and left to rest until testing time. Nevertheless, this protocol may rapidly lead to low and 0 slump values that will not be useful in evaluating the material structural build-up. ...
The critical assessment of the applicability of fresh concrete test methods for characterizing printable concrete quality and its structural build-up rate is rare in the literature. To address this gap, this study evaluates the potentials and limitations of eight offline test methods (hand vane, rheometer, compressive strength, squeeze flow, penetrometer, ultrasonic pulse velocity, slump, and flow table) and two inline test methods (slug test and extruder torque measurement). This research proposes a new parameter called “performance index” to assess the capability of any test to detect structural buildup. The study establishes a ranking of the eight offline tests on the proposed performance index and evaluates the advantages and disadvantages of each test in terms of portability, price, required human labor, and material. The results of this study can be used as a first guideline to select a proper quality control test for industrial 3D concrete printing construction.
... The portable vane is a simple and reliable test method to determine the structural build-up of concrete, as shown in Fig. 4 [45,46]. The equipment includes the square bucket, four-vaned steel shaft, and torque-meter with precision of 0.1 N m and a capacity of 500 N m. ...
... The use of portable vane to test the static yield stress led to a 160% higher value compared to the co-axial rheometer. This can be mainly attributed to the different shear history between the tests [45,46]. In the case of the co-axial rheometer, the same UHPC sample was employed to measure the static yield stress at different rest periods, with each test resulting in further disturbance of the material. ...
... In the case of portable vane test, three samples were employed to measure the static yield stress at three different rest periods, with each sample kept undisturbed until the time of testing. Therefore, the undisturbed sample has a higher level of particle flocculation compared to disturbed sample [45,46]. ...
Pre-saturated lightweight sand (LWS) and shrinkage reducing admixture (SRA) can be used to mitigate autogenous shrinkage of ultra-high-performance concrete (UHPC). However, their individual and synergetic effects on structural build-up that is essential for thin bonded bridge deck overlay rehabilitation and 3D printing have not been well understood. This study investigates the impact of LWS and SRA on structural build-up of UHPC with mini-slump flow of 190 ± 10 mm. Furthermore, the cement hydration, autogenous shrinkage, mechanical performance, and porosity of UHPC prepared with LWS and SRA were studied. Test results show that the structural build-up enhanced from 90 to 138 Pa/min with the increase of the LWS content from 0 to 25% given the lower surface coverage ratio of high-range water reducer onto cement particles. The incorporation of 2% SRA led to the lowest structural build-up of 64 Pa/min due to the lower bridging effect of early-age hydration products. The LWS17&SRA1 mixture exhibited higher structural build-up of 105 Pa/min, lower autogenous shrinkage of 340 με, as well as comparable compressive strength, elastic modulus, and flexural strength of 139 MPa, 48 GPa, and 19 MPa compared to the Reference mixture prepared without any LWS and SRA that had the corresponding values of 90 Pa/min, 535 με, 142 MPa, 50 GPa and 19 MPa, respectively. The comparable mechanical performance was due to the increased effect of LWS on cement hydration and pozzolanic reaction of silica fume counteracted the reduced influence of SRA.
... However, it is only an indirect measure and cannot reflect structural degradation under shear as the thixotropy is directly related to the change of viscosity rather than the shear stress [17]. Other experimental methods, including the static yield stress test, portable vane test [18] and inclined plate test [19], involve the rate of increase in static yield stress with the rest time. The methods listed above focus on the build-up process during rest, while the thixotropic behavior mainly happens when shearing. ...
... In SCC with high thixotropy values, the resistance to segregation increases while the lateral pressure applied to the mold decreases. In addition, the strength and durability of concrete are adversely affected by the increase in the amount of air-entrapped and the decrease in adherence between layers in concretes with this properties (Khayat et al., 2012). In 3D concretes, the number of layers and the constructability of the layers are directly related to the thixotropic behavior of the mixture (Zareiyan and Khoshnevis, 2017; Sanjayan et al., 2018). ...
Thixotropy is defined as a continuous decrease in viscosity over time when the flow is applied to a previously stagnant mixture, and the recovery of viscosity over time when the flow ends. Structural changes as a result of thixotropic behavior are very important in cementitious systems such as self-compacting concrete (SCC) and 3-dimensional (3D) concrete with large volumes of binders. In this study, the effect of the substitution ratio and fineness of the limestone powder (LP) obtained as waste from the aggregate quarry on the rheological properties of cementitious systems was investigated. For this purpose, a paste mixture was prepared by substituting LP with three different fineness (2500, 4800 ve 7000 cm2/g) with cement at the rate of 20% and 30% by weight. The water/binder ratio was kept constant as 0.28 in all paste mixtures. The mixtures were prepared so that the dynamic yield stress was constant at 110±55 Pa, taking into account parameters such as the measurement capacity of the rheometer used, homogeneous mixing of the mixtures and the use of minimum water reducing admixtures. Viscosity, dynamic yield stress (DYS), Herschel Buckley Index and thixotropic behavior of paste mixtures were investigated. It was understood that the LP substitution ratio and fineness significantly affect the rheological properties of the paste mixture. It was determined that both the dynamic yield stress and viscosity values decreased with the increase in the LP substitution ratio. It was also observed that the rheological parameters generally decrease with the increase in the usage ratio, regardless of the LP fineness. This decrease was even more evident in the measurements taken 20 minutes after casting. Experimental study revealed that LP fineness and substitution ratio have a significant effect on the structural recovery of paste mixtures.
... Due to the small penetration area, the uncontrolled penetration velocity at steady weight, the sensitivity of the Vicat test is relatively low, and no qualitative information about the structural build-up during the first minutes and hours of hydration before the initial setting time can be obtained. Khayat et al. [34] introduced another cone penetration test to evaluate the structural build-up of mortar or extracted mortar from concrete obtained by sieving. Some researchers are dealing with the estimation of the structural build-up using a texture analyzer. ...
The structural build-up of fresh cement paste is often considered as a purely thixotropic phenomenon in literature even though cementitious materials undergo a non-reversible hydration process that can have an influence on the structuration process. In the current paper a method is proposed to validate the impact of the non-reversible structural build-up. It is shown that fresh cement paste samples lose their structural gain almost completely due to thixotropy while the structural build-up due to hydration can be observed but occurs in a significantly lower order of magnitude over the course of the first hours of hydration. In addition, it is shown, that the chemical component of the structural build-up accelerates with the onset of the acceleration period of hydration, while its contribution in the entire structural build-up remains constant.
... The static yield stress was defined as the peak shear stress value (Liddel & Boger, 1996). The structural build-up of alkali-activated slag-based mixes was evaluated using the Athix index, which is widely used to quantify the build-up of cement-based materials (Khayat et al., 2012;Roussel, 2006). For each mixture, the evolution of static yield was evaluated, and the slope of this curve revealed the Athix index. ...
This study presents the rheological properties and performance of alkali-activa ted slag-based systems in terms of workability, static and dynamic yield stress, plastic viscosity, and compressive strength development. The effects of mineral additives such as fly ash, me-takaolin, and waste basalt powder on the rheology of alkali-activated slag-based systems were studied. Different types of activators, i.e., sodium hydroxide and sodium silicate, were used to determine the effects of activators. A series of trial mixtures were produced for 3D print applications. The results of this study showed that an alkali-activated binder system produced in this study has the potential to be used in 3D printing applications while utilizing waste mineral additives and contributing to sustainable and green binder design.
... Another rheological empirical method that was developed, is by making use of a penetration test. Examples of such tests are the cone penetration test, the Vicat needle penetration test and penetrometers in general [247]. The Cone Penetration (CP) test, developed according to a Swedish standard, is applicable to less stiff suspensions, while a needle penetration test is intended for rather stiff samples [247]. ...
... Examples of such tests are the cone penetration test, the Vicat needle penetration test and penetrometers in general [247]. The Cone Penetration (CP) test, developed according to a Swedish standard, is applicable to less stiff suspensions, while a needle penetration test is intended for rather stiff samples [247]. The Vicat needle was developed to determine the setting of a specimen and is measured by the penetration depth under self-weight [242]. ...
... The empirical correlations depend on the penetration speed and shape of the penetration needle. However, such devices may only provide sufficient reliability for rather stiff concretes or suspensions, i.e. suspensions with a high yield stress like traditional concrete or mortars [247]. ...
Concrete is, worldwide, the most used construction material. This is mainly due to advantages such as its free shape, availability and competitive cost. Innovations in concrete technology allowed for improvement in performance, quality, quantity, practical execution and possible realisations of structures. Although the introduction of self-compacting concrete (SCC) in the 1980s was very promising, SCC has not greatly been adopted by practitioners despite its many advantages. One of the reasons is because, still today, the practical execution, quality and performance of the construction passively relies on the fresh state (or rheological) properties of the concrete. Hence, once the concrete has been mixed and transported on site, it passively relies on the status quo with little room for adaptation. Shortcomings occur due to contradicting demands in rheological performances during different process stages. During transportation, pumping, formwork casting or extrusion the concrete requires to be highly flowable, contrary to directly after casting, 3D printing, shotcreting etc. requiring it to be as little flowable and to set as fast as possible.
In order to overcome issues related to the passive character of concrete, to overcome drawbacks associated with the SCC and to provide a next generation innovation in concrete technology allowing for improvement on multiple aspects, the development of Active Rheology and/or Stiffening Control (ARC & ASC) of concrete has been initiated by the SmartCast project. Active rheology control could be understood as the concept of actively triggering smart components in (cementitious) suspensions via an external signal --- which can take various forms such as (electro)magnetic signals --- after which the rheology or fresh state of the suspension is altered in a reversible or non-reversible manner. ASC & ARC may be able to resolve contradicting requirements in rheological performance in cementitious applications.
However, due its innovative character, ASC & ARC are a nearly unexplored domain of research in concrete technology. In spite of the vast research on concrete technology, the rheological behaviour of concrete is still not fully understood. This is especially the case for time-dependent rheological behaviour of concrete and more generally cementitious suspensions. Under time-dependent effects, two main aspects are understood affecting the rheological behaviour, i.e. thixotropy which is reversible and hydration which is irreversible. Especially due to their complexity, time-dependent effects are often omitted from concrete rheological studies, even though they can have a significant impact on the execution process and eventual performance. Instead of relying on vast, inconvenient and expensive experiments, numerically modelling the rheological behaviour allows for investigating the performance in certain applications, or may perhaps even provide a framework for mixture design. Rheological input for numerical simulations can be provided by quantification devices, known as rheometers. Since, significant disparities exist among rheometers, the rheological input is an additional uncertainty on top of appropriate constitutive cementitious behaviour modelling. Moreover, deficiencies exist in current modelling techniques, e.g. lacking time-dependent behaviour and more importantly ASC & ARC. In order to provide understanding and insights in ASC & ARC behaviour and potential applications, its modelling cannot lag behind. As part of ASC & ARC development in the SmartCast project, this doctoral dissertation aims at bridging the gap of modelling time-dependent behaviour of cementitious suspensions in view of ASC & ARC, providing a rheological quantification procedure and assessing its adequacy. This research aims to provide fundamental understanding in flow behaviour of cementitious suspensions and how to adequately quantify and model it, independent of time, time-dependent (thixotropic) and with respect to ASC & ARC.
The main investigated research hypothesis is whether and how adequately ASC & ARC can be captured by a concept of kinetic temporal evolution of an internal structure, driven by structural build-up and break-down. Neither the full extent of cementitious behaviour was investigated, nor the full extent of potentially possible ASC & ARC. Passive and Active Stiffening Control (PSC & ASC) of cementitious pipe flows were investigated from a fundamental viewpoint, because pumping is an inevitable part of the concrete or cementitious execution process. Paste suspensions form the main baseline for investigating cementitious pipe flows. That is because if paste could adequately be described and modelled, it can easily be superimposed or extrapolated to more complicated flow behaviour involving e.g. shear induced particle migration. Thereby, fundamental and widely applicable knowledge may be obtained in view of ARC. Moreover, such more complicated flow behaviour is still a vast, on-going research domain itself. On the one hand, the adequacy of constitutive behaviour modelling and quantification was assessed. On the other, the numerical adequacy was assessed, especially because numerical simulations rely on rheological input, which uncertainties are directly embedded as a consequence. Assessing the adequacy of the numerical framework is, therefore, a feedback loop between rheological input and numerical outcome. The numerical framework was assessed on three aspects with gradually increased complexity. First the modelling adequacy was assessed independent of time via so-called Bingham behaviour, then including thixotropic behaviour as a predecessor of ASC & ARC and lastly active stiffening control behaviour. Practically, the Bingham behaviour was established by means of limestone powder suspensions, the thixotropic behaviour with additional nano-clay and the ASC & ARC behaviour via cementitious suspensions with magneto-rheological fly ash. To this end, a modular, experimental pumping set-up was designed, referred to as the Small Pumping System (SPS), and a numerical framework was developed based on OpenFOAM, in which time-dependent behaviour as well as behavioural aspects of ASC & ARC were implemented. Furthermore, transparent, easy-to-use rheological quantification procedures were developed to describe cementitious flow behaviour independent of time (by the Bingham model), with thixotropy (by the simplified Roussel model) and with active stiffening control (by a proposed dynamic magneto-structuration model). Based on pumping experiments and rheological quantifications, simulations were performed using a finite volume method.
Although the library of constitutive behaviour models is vast and can be fairly complicated, it can be stated that rheological properties can be quantified and depending on the context, it may suffice to describe the flow behaviour of cementitious suspensions from a macroscopic viewpoint. Independent of time a Bingham model characterised by a yield stress and a plastic viscosity suffices. If time-dependent (thixotropic) behaviour is significant, it cannot be omitted from the analysis. It can be included, e.g. by a simplified model proposed by Roussel, for which a transparent, semi-coupled quantification methodology was developed. However, one should pay attention to potential biases involved with rheological quantification, which is part of the difficulty of the state of the art in rheometry. Therefore, it is advised to quantify rheology from a set-up closely related to the engineer's aimed application in order to avoid biases. However, one should be aware not to overlook significant physical phenomena, otherwise the quantification and behaviour description does not suffice as such. If, for instance, shear induced particle migration is significant, which is the case for concrete pumping, microscopic models are inevitable in which the yield stress and the plastic viscosity or even time-dependent parameters are a function of the particle concentration. Non-dimensional numbers may provide a useful indication on the occurring significance of certain effects or on-going phenomena. In particular, three dimensionless parameters are useful, i.e. the pressure number, the non-dimensional discharge and the thixotropy factor. As such, a so-called discharge diagram could be insightful. Fundamental insights were provided based on non-dimensional expressions of Poiseuille flow, its extensions and a derived thixotropic extension based on the simplified Roussel model. The derived, but not further explored, non-dimensional (thixotropic) slippage flow expressions show a huge potential for further investigation. From an experimental viewpoint, investigating the influence of a pre-wetting, pre-lubricating or hydrophobic coating of the pipe surface is of future importance.
Based on a sound, five-fold numerical validation, it can be stated that Computational Fluid Dynamics (CFD) can be used to model cementitious suspensions to a significantly accurate extent and from a macroscopic viewpoint only. Although, it should be nuanced that CFD is and will not be able to precisely capture non-Newtonian behaviour, especially with regard to yielding behaviour. A Generalised Newtonian Approach (GNA) will always be a comprise, but if dealt with in an appropriate way, useful results can be provided. At least if considering a proper mesh design, if using proper regularisation and under-relaxation, if using rheological input close to the aimed application thereby omitting uncertainty due to rheometry --- significantly accurate numerical simulations can be achieved, with a theoretical error below 1%. However, in spite of using a sliding pipe rheometer which is closer to pumping than a parallel plate rheometer, an overestimation (from a near perfect match up to a relative error of 100%) was obtained when compared with pumping experiments. This error was mainly attributed to biases in rheological quantification, as well as a slight reduction in pumping pressure loss due to limited intermixed water near the pipe wall surface. Irrespective of significantly accurate theoretical simulations, a numerical simulation is only an approximation of a considered physical problem constrained by its mathematical simplicity and assumptions. Therefore, it is of importance to have sufficient understanding of the problem that needs resolving and the limits of the selected numerical technique. Hence, all significant phenomena should be modelled in order to achieve an adequate numerical simulation. Just as any other technique, it has disadvantages and advantages. One simply needs to bear these in mind and take care of them. Although velocity under-relaxation was able to cope with stability and accuracy issues due to viscoplastic regularisation of yield stress fluids for CFD simulations with a GNA approach, a broader spectrum of simulations still remains unexplored. Especially investigating lubrication pipe flows with respect to regularisation, stability and accuracy is a promising future research path with practical relevance. Other viscoplastic regularisation techniques as well as the augmented Lagrangian technique could be investigated in the future. Apart from the viscoplastic regularisation problem, lubrication flows could also be investigated by means of a slippage boundary condition, implementation of coupled Shear Induced Particle Migration (SIPM), as well as coupled Computational Fluid Dynamics - Discrete Element Method (CFD-DEM) and other techniques. However, calibration and validation of those techniques is not straightforward due to the high model complexity.
Valorising the main posed hypothesis, it can be stated that, indeed, it is possible to both qualitatively and quantitatively describe PSC as well as ASC & ARC --- expressed in the form of magneto-rheological behaviour --- by means of a concept of internal structure and its temporal kinetic evolution characterised by a structural build-up and break-down term. Although Passive Stiffening Control (PSC) could not be further verified for more complicated behavioural features due to involved biases in rheology and physical conditions (temperature effects) during the thixotropic pumping tests, predictions by means of a kinetic, temporal approach of an internal structure with a relative overestimation up to 100% were reasonable. Assessment and predictions of ASC were more pronounced, as the numerical simulations provided results both viable and in the same order of magnitude as the magneto-rheological pumping test with ASC. However, this does not prove a hypothesis, it is only evidenced that viable, qualitative results can be captured by the proposed magneto-structuration model. However, the full extent of the magnetic response was not captured by dynamic magneto-structuration only. Therefore, the hypothesis is accepted that the combination of predominant magneto-structuration and subordinate magnetic flow confinement can well capture the magneto-rheological cementitious behaviour. As long as no other evidence is found to falsify or reject the postulated hypothesis on dynamic magneto-structuration, it still stands. The proposed magneto-structuration model does not capture all behavioural features in view of ASC & ARC, but it allows to both qualitatively and quantitatively conceptualise ASC. Hence, it can serve to provide insights in ASC & ARC or to provide a fundamental building block in which more complicated behaviour in general can be incorporated. In perspective of ASC & ARC, promising results were obtained allowing for improved formwork leakage control or 3D printing buildability. Further developments of active triggering controls, e.g. an activating printing nozzle (or pipe) could be explored. The proposed, more general magneto-structuration model could serve as corner stone in development of more complicated and versatile features of ARC, such as micro-vibration improving the flowability, anisotropic magnetisation, magnetic acceleration for improved pumping performance etc. ARC, not only in the form of a magneto-rheological response, nor by only a magnetic fly ash, shows a huge potential for future developments with practical relevance. E.g. making use of magnetite, maghemite or other minerals as well as electrochemically or magnetically activated polymer developments. Thixotropy and passive stiffening control can also be further examined, both numerically as experimentally, given the provided quantification procedure. However, for future thixotropy studies, use of actual cement is advised to avoid exceeding the behavioural context. Future experimental and numerical investigations with respect to pumping re-initiation are relevant for practice.
