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Particle size distribution of raw materials: hydrated lime (continuous line) and cement (dashed line).
Source publication
The rheological properties of a suspension of lime in water (lime putty) are studied with the help of creep tests in a wide range of deformations including very small values. The results are compared with those obtained with a cement paste and several similarities between the two systems are observed. It is shown that the apparent yield stress of a...
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Context 1
... hydrated lime has a tendency to aggregate, which can lead to an overestimation of the particle size, the sample was first submitted to ultrasound during one minute (Sonics - 850W). The cement exhibited a particle size distribution (see Figure 1) spreading from 1 to 50 m with a mean size around 10 m while the hydrated lime contained particles in the range 1 to 10 m with an average size around 4 m. The pastes were prepared by pouring the material powder in water, then mixing by hand for one minute and at 600 rpm with a mechanical mixer for another minute. ...
Context 2
... clearly appears from the position of the step, which is simply shifted towards shorter time as the solid fraction is increased. Under these conditions it is possible to plot all the data along a master curve by scaling the time by a factor ( t ) which depends on the solid fraction (see Figure 10). This means that the elastic modulus may be written as ...
Citations
... In materials exhibiting thixotropic behavior, such as in this case, both the static yield point (measured on the ascending branch of the flow curve) and dynamic yield point (measured on the descending branch of the flow curve) depend on the previous flow history [46]. Under these conditions, the data from the descending branch are likely to be the closest to the effective flow curve of the material; that is, under conditions of steady-state flow [47]. Moreover, in the descending branches of the flow curves for all suspensions, the internal structure state reached after the first two ramps of the established rheological protocol allows for the erasure of shear history from the samples, enabling the analysis of each suspension under identical conditions. ...
... Lime pastes, similar to Portland cement pastes, exhibit a certain amount of destructuring during flow, evolving their structure in both reversible and irreversible manners and being influenced by flow heterogeneities that arise throughout the test [47]. The same behavior is exhibited in lime pastes with mineral additions such as NVP and MK, as experimentally confirmed in this research. ...
Natural hydraulic lime (NHL)-based binders play a crucial role in preserving cultural heritage structures, ensuring integrity and longevity. Beyond traditional uses, these binders exhibit potential for integration into both non-structural and structural components, being compatible with innovative manufacturing processes such as digital fabrication. Meticulously designed grouts, with applicability in their fresh and hardened states, are essential for heritage stability. This study explores the relationships between mineral additions, chemical admixtures, and lime for grout formulations, aiming to advance our understanding and inform the optimization of materials for heritage restoration. Key questions include the influence of natural volcanic pozzolan (NVP) and metakaolin (MK) on rheology and the impact of varying ratios of superplasticizer on NHL-based grout's rheologi-cal behavior. This systematic evaluation of rheological parameters aims to innovate mix designs, expanding NHL-based binders' applicability in construction and science. Our hypotheses suggest that well-designed lime grout formulations, incorporating NVP and MK, can enhance rheological properties, addressing challenges in sustainable construction and heritage conservation. This research provides valuable insights for optimizing lime-based materials, fostering advancements in heritage restoration, and promoting wider NHL-based binder adoption in diverse construction applications.
... After an hour the lowest slump flow was recorded for the 10EA mixtures prepared with polypropylene fibers. This can be attributed to early hydration of the EA that can reduce flowability [52][53][54]. Additionally, hybrid synthetic fibers due to shorter length, lower density, and higher content present higher surface area compared to the hybrid steel-synthetic fibers that can reduce the mortar thickness around them and hence flowability. ...
... (M), led to the lowest slump value, which could be attributed to high water absorption of the EA and synthetic fibers. The hydration caused by the use of relatively high content of EA results in the formation of portlandite and higher specific surface area of compared to cement, which leads to slump reduction [51,52,65]. Higher slump values in the mixtures made with steel fibers, despite the lower HRWR demand, can be related to lower surface area and water absorption of the steel fiber compared to the synthetic fibers [66]. ...
... With regard to the rheological characterization of lime and lime and pozzolana pastes, there are few studies. Fourmentin et al. [44] analyzed lime slurries and observed a better fit to the Herschel-Bulkley model, where fluid needs a flow stress to initiate flow and apparent viscosity decreases with increasing shear rate. Although in paper by Betioli et al. [45], cementitious pastes have better adjusted to model in question, they are usually characterized as Bingham fluids [46][47][48]. ...
Lime mortars have been indicated for restoration and conservation interventions in historic buildings, however, the slow hardening of these mortars does not favor their use and dissemination in construction areas. The inclusion of pozzolans improves these properties, and although the results achieved are not close to those found in conventional cementitious mortars, they are seen as compatible materials for restoration services, since they present moderate mechanical responses and chemical compatibility. This chapter aims to show the impact of different pozzolans on fresh and hardened lime mortar’s properties, including mechanical, rheological, and microstructural properties. In addition, an overview of historical mortars is presented.
... Furthermore, many works of literature have reported stresshysteresis for different materials during cyclic shear rate up and down sweeps test [8,20,48,76,[85][86][87][88][89][90][91]. Using our model, we have predicted stress-hysteresis during strain rate sweep test for irreversible (infinite thixotropic time scale) and reversible (finite thixotropic time scale) thixotropic materials. ...
Most earlier thixotropic elasto-visco-plastic models follow the quasi-static pre-yielding linear elastic assumption of Oldroyd's 1946 model. To develop a new model, the present work considers a more realistic pre-yielding non-linear visco-elastic and plastic deformation. Our model is valid for reversible (finite thixotropic time scale) and irreversible (infinite thixotropic time scale) thixotropic materials. Despite being a simple algebraic equation, our model appropriately explains both the viscosity plateau at low shear rates and the diverging zero shear rate viscosity, using the same parameters but different shear histories. Our model also predicts experimentally observable transient shear banding due to microstructure breakage by shear rejuvenation and steady-state shear banding due to aging. Furthermore, our model predicts initial gel structure (waiting time) dependent stress overshoot during shear rate startup flow, different stress hysteresis in shear-rate ramps, sudden stepdown shear rate test results, and viscosity bifurcation during creeping flow phenomena effectively. Depending on shear histories, at steady state, our model reduces to either Bingham model, Herschel Bulkley type model with shear rate dependent yield stress, or Newtonian fluids model. Our model requires only four parameters for the irreversible and five for the reversible thixotropic-elasto-visco-plastic (TEVP) model obtainable from the rheometer test. Our model favourably predicts a series of recent experimental results. The current framework has the potential to provide a possible physical interpretation of the Bingham model. It also has the capability to predict a delayed flow start using an appropriate structure degradation kinetic.
... Furthermore, as reported by Roussel et al. [23], in the very first stages of the shearing process, the shear stress-shear strain curve can exhibit an abrupt change in the slope (Figures 4 and 5). Fourmentin et al. [38] reported the same trend. In fact, at a very low shear strain, there is a quick increase in the shear stress associated with a high instantaneous shear modulus, which could characterize a very stiff material [23,38]. ...
... Fourmentin et al. [38] reported the same trend. In fact, at a very low shear strain, there is a quick increase in the shear stress associated with a high instantaneous shear modulus, which could characterize a very stiff material [23,38]. This slope change is associated with a very low strain which cannot be associated with the flow onset. ...
With the interest aroused by the development of modern concretes such as printable or self-compacting concretes, a better understanding of the rheological behavior, directly linked to fresh state properties, seems essential. This paper aims to provide a phenomenological description of the rheological behavior of cement paste. The first part is devoted to the most common testing procedures that can be performed to characterize the rheological properties of cement suspensions. The second one deals with the complexities of the rheological behavior of cement paste including the non-linearity of flow behavior, the viscoelasticity and yielding, and the structural build-up over time.
... During the initial dissolution stage, a sharp exothermic peak mainly corresponds to the dissolution of silicate and aluminate phases after the first contact of cement with water [53]. All the woods greatly affected cement kinetics at this stage by decreasing heat flow and displacing peaks compared to the control sample. ...
... During the induction stage, the energy liberated by hydration reactions remains low and almost constant for about two or three hours [53]. After that, there is an increase in the C 3 S dissolution rate and C-S-H gel nucleation and growth stimulation. ...
... After some hours of low activity, the thermal flux increases until reaching a maximum value during acceleration. Next, it decreases during the deceleration period [53]. The cement setting that corresponds to the third stage is responsible for changing its strength and water sensitivity over time [58]. ...
The combined effect of wood chemical composition, anatomical traits, and density on cement curing, matrix-reinforcement interface, and final performance of cement-bonded particleboards (CBPBs) needs deeper investigation. Besides, many uncharacterized Amazon hardwoods challenge softwoods' often-reported superiority for producing CBPBs. Certified Cordia goeldiana, Brosimum parinarioides, Parkia gigantocarpa, and Pinus oocarpa woods were characterized by histology, cell biometry, basic density, and chemical composition. The hydration kinetics of the Portland cement pastes was evaluated by isothermal heat conduction. The CBPBs production parameters were wood:cement ratio of 1:2.75, water:cement ratio of 1:2.5, 4% of CaCl 2 additive (based on cement mass), and target density of 1.25 g cm − 3. They were submitted to physical and mechanical tests, and the polished surfaces were analyzed by scanning electron microscopy. The cement kinetics showed that wood's higher contents of extractives and hemicelluloses harmed the initial dissolution stage of Portland cement curing but not the essential stages of acceleration and deacceleration. C. goeldiana wood showed the highest compatibility indexes with cement, and all hardwoods surpassed P. oocarpa. Thin-walled fibers, big-diameter fibers, and big-diameter pores favored cement impregnation. Debonding at wood-cement interfaces of CBPBs reinforced with higher-density woods was critical for crack propagation throughout the matrix. Less critical inter-particle cracks occurred in CBPBs reinforced with lower-density woods. The better interface and the highest volume of wood particles of the lowest-density P. gigantocarpa wood provided the CBPBs with the best physical and mechanical performance overcoming the chemical incompatibility relevant only in the initial dissolution stage of cement curing.
... For air lime, the scarcely available literature focuses mainly on putties, pastes and grouts. For instance, Atzeni et al. [36], Ruiz-Agudo and Rodriguez-Navarro [37,38], Arizzi et al. [39] and Boháč and Nečas [40] dealt with the influence of the type and/or ageing time of the lime used on the rheological properties of lime putties, whereas Rago [41] and Fourmentin et al. [42] compared the rheological behaviour of lime pastes with that of cement ones. Additionally, Izaguirre et al. [43] and Fernández et al. [44] briefly addressed the effects of water-retaining and plasticizing admixtures, respectively, on the rheological properties of lime pastes, and Azeiteiro et al. [45] studied the effects of the same admixtures on lime grouts for the consolidation of old renders. ...
This paper evaluates the influence of water content and mixing conditions (mixing time and sequence of addition of the constituents) on the fresh state properties of lime-based materials and their impact on the hardened state properties. Higher water contents allowed an increased fluidity and lower torque, yield stress and plastic viscosity values. In turn, a longer mixing time with the aggregate caused a progressively stiffer mortar and a substantial increase in the torque, yield stress and plastic viscosity values due to the breakdown of lime agglomerates that consume part of the free water available to lubricate the mix. A longer mixing time without the aggregate caused similar trends, albeit to a much lesser extent. The water content and mixing conditions also had a major impact on the resulting porous structure of lime mortars and, thus, on their mechanical strength.
... Stress as a function of the rate of deformation for different values of thixotropic time scale (a) T0 = 1 s, (b) T0 = 100 s, (c) T0 = 10000 s, and (d) T0 -> infinity, other parameters m=100, % =0.5 Pa s, + =5 Pa s, G0=5000 Pa are kept constant for all plots.Furthermore, many literatures have reported stress-hysteresis for different materials during cyclic shear rate up and down sweeps test(7,22,28,(73)(74)(75)(76)(77)(78)(79)(80). Using our model, we have predicted stress-hysteresis during strain rate sweep test for irreversible (infinite thixotropic time scale) and reversible (finite thixotropic time scale) thixotropic materials. ...
Formulating an appropriate elasto-viscoplastic constitutive equation is challenging, especially for a model describing pre-yielding solid and post-yielding liquid behaviours. Oldroyds 1946 formulation was one of the first models explaining it, however, assumptions of a simple linear elastic and quasi-static deformation before yielding made his model idealistic. At the same time, the quasi-static pre-yielding deformation assumption open-up the possibility for pre-yielding viscous and plastic deformation in the absence of quasi-static conditions. Most early models followed Oldroyds pre-yielding linear elastic assumption. Here, we discuss the structural parameters based thixotropic non-linear elasto-viscoplastic constitutive model valid for reversible and irreversible thixotropic materials. In this work, we have considered non-linear elastic and plastic behaviours before yielding. Despite being a simple algebraic equation, our model explains both the viscosity plateau at low shear rates and the diverging zero shear rate viscosity, using the same parameters but different shear histories. Our model also predicts experimentally observable transient and steady-state shear banding. Furthermore, our model effectively predicts waiting-time-dependent stress overshoot during startup flow, stress hysteresis in shear ramps, sudden stepdown shear rate test results, and viscosity bifurcation phenomena. At the steady state, it reduces to either Bingham, Herschel Bulkley type, or Newtonian fluids model, depending on shear histories. Our model requires only four and five for the irreversible and reversible model, respectively, compared to six or seven parameters required by the existing model. With fewer parameters, our model favourably predicts recent experimental results. The current framework has the potential to provide a possible physical interpretation of the Bingham model.
... Since this study, many thixotropic and non-thixotropic complex materials in the literature have been reported to show hysteresis. Some of these materials are mineral oil [16 and 17], lithographic ink [18], waxy potato starch [19], cellulose nanocrystal suspensions [20], mud and cement pastes [21][22][23], sodium alginate solutions [24], solder and adhesive pastes [25], ferrofluids [26], sodium carboxymethylcellulose hydrogels [27], fluorinated guar gums [28], Carbopol microgels [29], microfibrillar cellulose water dispersions [30], sodium polyacrylate Laponite solution [31], polystyrene solutions [32], waxy crude oil [33], acrylic emulsion paints [34], pulp fibre suspensions [35], colloidal star gels [36], foams and emulsions [37], Ludox gels [38], etc. This list contains both non-thixotropic viscoelastic materials as well as thixotropic materials. ...
Rheological characterization of complex fluids subjected to cyclic shear-rate sweep often exhibits hysteresis. Since both viscoelastic and thixotropic materials show hysteresis loops, it is important to understand distinguishing features (if any) in the same shown by either. Lately, there has been substantial work that attempts to relate the area enclosed by the hysteresis loop with the manner in which shear rate is varied in the cycle, in order to infer thixotropic parameters of a material. In this work, we use the nonlinear Giesekus model to study its response to the application of cyclic shear-rate sweep. We find that this model produces each type of qualitatively similar hysteresis loop that has hitherto been ascribed to thixotropic materials. We also show that the area of the hysteresis loop for a viscoelastic material as a function of sweep rate shows bell-shaped/bi-modal curves as has been observed for thixotropic materials. This study illustrates that caution needs to be exercised while attributing hysteresis loops and associated features observed in a material exclusively to thixotropy. Another feature related to the hysteresis loop is the occurrence of shear banding instability. We find that viscoelastic hysteresis may not have any connection to shear banding instability.
