Rheological Behaviour and Flow Properties of Alkali-Activated Materials

2021 ◽  
pp. 257-269
Author(s):  
Mohammed Fouad Alnahhal ◽  
Taehwan Kim ◽  
Ailar Hajimohammadi
Keyword(s):  
Rheological Behaviour ◽  
Flow Properties ◽  
Alkali Activated

Rheological Properties of Alkali-Activated Brick Powder Based Pastes: Effect of Alkali Activator and Silicate Modulus

2018 ◽  
Vol 276 ◽  
pp. 185-191
Author(s):  
Martin Vyšvařil ◽  
Pavla Rovnaníková ◽  
Martin Keppert
Keyword(s):  
Yield Stress ◽  
Rheological Behaviour ◽  
Gel Formation ◽  
Material Behaviour ◽  
Flow Properties ◽  
Rheological Characterization ◽  
Polymerization Kinetic ◽  
Brick Powder ◽  
Viscous Modulus ◽  
Alkali Activated

The rheological behaviour of alkali-activated materials prepared by activation of a brick powder by alkaline solution (alkali + water glass) is described. The influence of the composition of activation solution (NaOH vs. KOH, varied silicate modulus) on the flow properties (yield stress, consistency coefficient, fluidity index) and the evolution of the elastic modulus (G ́) and the viscous modulus (G ́ ́) over time were studied. The rheological characterization was completed by frequency sweep tests with the aim of investigating the material behaviour more in detail. The results show that the pastes are thixotropic suspensions with very low yield stress. The potassium activator decreases the yield stress and viscosity of the pastes and retards the polymerization kinetic. The brick pastes become more rigid and more viscous with increasing silicate modulus. This also leads to an acceleration of gel formation in brick pastes.

scholarly journals Alkali-activated laterite binders: Influence of silica modulus on setting time, Rheological behaviour and strength development

2021 ◽  
pp. 100175
Author(s):  
Cyriaque Rodrigue Kaze ◽  
Adeyemi Adesina ◽  
Gisèle Laure Lecomte-Nana ◽  
Thamer Alomayri ◽  
Elie Kamseu ◽  
...  
Keyword(s):  
Setting Time ◽  
Rheological Behaviour ◽  
Strength Development ◽  
Alkali Activated

scholarly journals Pinch and swell structures: evidence for brittle-viscous behaviour in the middle crust

2015 ◽  
Vol 7 (2) ◽  
pp. 1517-1554
Author(s):  
R. Gardner ◽  
S. Piazolo ◽  
N. Daczko
Keyword(s):  
Viscous Flow ◽  
Lower Crust ◽  
Brittle Failure ◽  
High Strain ◽  
Rheological Behaviour ◽  
Scale Model ◽  
Flow Properties ◽  
Near Surface ◽  
Heterogeneous Rocks ◽  
The Matrix

Abstract. The flow properties of middle to lower crustal rocks are commonly represented by viscous flow. However, examples of pinch and swell structures found in a mid-crustal high strain zone at St. Anne Point (Fiordland, New Zealand) suggest pinch and swell structures are initiated by brittle failure of the more competent layer in conjunction with material softening. On this basis we develop a flexible numerical model using brittle-viscous flow where Mohr–Coulomb failure is utilised to initiate pinch and swell structure development. Results show that pinch and swell structures develop in a competent layer in both Newtonian and non-Newtonian flow provided the competent layer has enough viscosity contrast and initially fails brittlely. The degree of material softening after initial failure is shown to impact pinch and swell characteristics with high rates of material softening causing the formation of thick necks between swells by limiting the successful localisation of strain. The flow regime and yielding characteristics of the matrix do not impact pinch and swell structure formation itself, so long as the matrix is less competent. To aid analysis of the structures and help derive the flow properties of rocks in the field, we define three stages of pinch and swell development and offer suggestions for measurements to be made in the field. Our study suggests that Mohr–Coulomb behaviour combined with viscous flow is an appropriate way to represent the heterogeneous rocks of the middle to lower crust. This type of mid-crustal rheological behaviour has significant influence on the localization of strain at all scales. For example, inclusion of Mohr–Coulomb brittle failure with viscous flow in just some mid-crustal layers within a crustal scale model will result in strain localisation throughout the whole crustal section allowing the development of through-going high strain structures from the upper crust into the middle and lower crust. This localization then has a significant effect on developing near-surface structures.

The Influence of Plasticizer Content and Type on the Rheological Behaviour of Plastisol Used in Coated Fabrics

2000 ◽  
Vol 30 (1) ◽  
pp. 50-50
Author(s):  
A. Zadhoush ◽  
M. A. Alsharif
Keyword(s):  
Statistical Analysis ◽  
Power Law ◽  
Research Work ◽  
Rheological Behaviour ◽  
Flow Properties ◽  
Newtonian Flow ◽  
Plasticizer Content ◽  
Rheological Measurements ◽  
Coated Fabrics ◽  
Power Law Index

Coating pastes need to have very specific rheological properties because of the methods in which they are applied. Composition of the paste can be formulated in such a manner to achieve the desired rheological behaviour. In this research work rheological measurements of paste with nine various plasticizer content using DOP and DOA, and PVC-E with three k-values (69, 70, 75) were studied. The results indicate that pastes are characterized by a non-Newtonian pseudoplastic flow under the studied conditions. The power-law index ( n) values of the pastes show that the flow properties of pastes change to Newtonian flow above 50 phr plasticizer content. It was also found that the consistency index (k) of the pastes were decreased with increasing plasticizer content. Statistical analysis carried out show very good correlation between the studied parameters.

scholarly journals Pinch and swell structures: evidence for strain localisation by brittle–viscous behaviour in the middle crust

Solid Earth ◽  
2015 ◽  
Vol 6 (3) ◽  
pp. 1045-1061 ◽  
Author(s):  
R. L. Gardner ◽  
S. Piazolo ◽  
N. R. Daczko
Keyword(s):  
Viscous Flow ◽  
Country Rock ◽  
Shear Bands ◽  
Rheological Behaviour ◽  
Scale Model ◽  
Flow Properties ◽  
Strain Localisation ◽  
Near Surface ◽  
Middle Crust ◽  
Alternative Representation

Abstract. The flow properties of middle crustal rocks are commonly represented by viscous flow. Examples of pinch and swell structures found in a high strain zone at St. Anne Point (Fiordland, New Zealand) and Wongwibinda (N.S.W., Australia) suggest pinch and swell structures may be initiated by brittle failure of the more competent layer in conjunction with subsequent material softening. On this basis we develop a numerical model where Mohr–Coulomb constitutive strain localising behaviour is utilised to initiate pinch and swell structure development. Results show that pinch and swell structures develop in a competent layer in both Newtonian and non-Newtonian flow, provided the competent layer has sufficient viscosity contrast and can localise strain to form shear bands. The flow regime and strain localising characteristics of the surrounding country rock appear not to impact pinch and swell structure formation. The degree of material softening after the initial strain localising behaviour is shown to impact pinch and swell characteristics, while extensive material softening causes the formation of thick necks between swells by limiting the focused localisation of strain into shear bands. To aid analysis of the structures and help derive the flow properties of rocks in the field, we define three stages of pinch and swell development and offer suggestions for measurements to be made in the field. Our study suggests that Mohr–Coulomb strain localising behaviour combined with viscous flow is a viable alternative representation of the heterogeneous rheological behaviour of rocks seen in the middle crust. This type of mid-crustal rheological behaviour can have significant influence on the localisation of strain at all scales. For example, inclusion of Mohr–Coulomb strain localising behaviour with viscous flow in just some mid-crustal layers within a crustal-scale model can result in significant strain localisation, extending from the upper crust into the middle crust. This localisation also influences the development of near-surface structures.

Ageing Effect on Aerial Lime Mortars Rheology

2008 ◽  
Vol 587-588 ◽  
pp. 872-876
Author(s):  
M.P. Seabra ◽  
Joao A. Labrincha ◽  
Victor M. Ferreira
Keyword(s):  
Rheological Properties ◽  
Water Intake ◽  
Ageing Time ◽  
Volume Ratio ◽  
Rheological Behaviour ◽  
Ageing Effect ◽  
Flow Properties ◽  
Intake Process ◽  
Key Characteristics ◽  
Lime Mortars

One of the key characteristics of fresh mortars is their rheological behaviour since it determines the material workability and has a clear influence on the hardened product final properties. Indeed, mortars rheological properties are extremely important since several factors, related with placement, consolidation, durability and strength depend on the flow properties of the mortar paste. In this work, the effect of ageing time on the rheological properties of fresh aerial lime-based mortars was investigated. Mortars having a 1/3 binder/aggregate volume ratio were studied as a function of ageing time. The influence of a water retaining agent (0.1 wt. %) addition in these mortars was also analysed. Mixing and ageing have a clear influence in the water intake process ruling over the rheological behaviour of this type of mortars.

scholarly journals Rheology, Mechanical Properties and Porosity of Ternary Alkali-Activated Binders Based on Mining Mud Waste with Waste Glass and Metakaolin

CivilEng ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 236-253
Author(s):  
Abdelhakim Benhamouda ◽  
João Castro-Gomes ◽  
Luiz Pereira-de-Oliveira
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Yield Stress ◽  
Relative Yield ◽  
Rheological Behaviour ◽  
Waste Glass ◽  
Plastic Viscosity ◽  
Rheological Parameters ◽  
Alkali Activated Binders ◽  
Alkali Activated

Alkali-activated materials have the potential to replace Portland cement in certain applications. To better understand these binders’ properties, it is relevant to study their rheological behaviour at early ages, like in the case of Portland cement paste. There are already many studies on the rheological behaviour of these materials in the available literature, using fly ash, metakaolin, and ground granulated blast furnace slag as precursors. However, this study discusses the rheological behaviour, mechanical properties, and porosity of ternary alkali-activated binders based on mining mud waste, waste glass, and metakaolin. The precursor consisted of a volume mix of 70% of tungsten mining waste mud, 15% glass waste, and 15% of metakaolin. The activator was a combination of sodium hydroxide and sodium silicate solution. Five activator/precursor (A/P) ratios (0.37, 0.38, 0.39, 0.40, and 0.4) were studied. The result showed that the activator/precursor ratio affects the rheology of paste and their rheological behaviour fit the Bingham model. The relative yield stress (g) and plastic viscosity (h) increased inversely with the A/P ratio, while the workability increased proportionally. Furthermore, some empirical models are proposed to describe the characteristic of yield stress: plastic viscosity and spread diameter versus the A/P ratio and time with a correlation between the rheological parameters and the spread diameter. The increase in A/P ratio has also followed a decrease in compressive strength in all tested samples for all the ages. As expected, an increase of the porosity accompanied the increase of the A/P ratio.

scholarly journals Rheological Behavior of Sumac (Rhus coriaria L.) Extract as Affected by Temperature and Concentration and Investigation of Flow Behavior with CFD

2020 ◽  
Vol 10 (6) ◽  
pp. 7120-7134
Keyword(s):  
Arrhenius Equation ◽  
Flow Behavior ◽  
Rheological Behaviour ◽  
Effect Of Temperature ◽  
Sudden Expansion ◽  
Flow Properties ◽  
Rotational Viscometer ◽  
Different Temperatures ◽  
Rhus Coriaria ◽  
Temperature Ranges

The purpose of this study is to investigate the rheological properties of sumac extract in different concentrations at different temperatures as well as its flow behavior in sudden expansion-contraction and at 90o elbow with CFD. The rheological behaviour of sumac extract in different concentrations (45.65%, 50.44%, 55.53%, 60.32%, and 65.13% total solids) were evaluated using a rotational viscometer at different temperatures (10, 20, 30, 40 and 50 C). Sumac extract samples showed Newtonian flow properties in these temperature ranges. Arrhenius equation was used to determine the effect of temperature. Ea value varied in the range of 11.16-34.35 kJ/mol, which diminished with a decrease in concentration. Power and Exponential models were used to characterize the effect of concentration on flow behavior. Time average velocity vector and contours, vorticity contours, kinetic energy contours, and pressure contours are given to show the flow behavior of sumac extract.

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