Compressive Yield Stress of Cement Paste

1994 ◽  
Vol 370 ◽  
Author(s):  
Kelly T. Miller ◽  
Wei Shi ◽  
Leslie J. Struble ◽  
Charles F. Zukoski
Keyword(s):  
Yield Stress ◽  
Calcium Aluminate ◽  
General Property ◽  
Volume Fraction ◽  
Initial Structure ◽  
Compressive Behavior ◽  
Initial Volume ◽  
Initial Volume Fraction ◽  
Compressive Yield Stress ◽  
Aluminate Cement

AbstractCompressive yield stresses have been measured for pastes (0.35 ≤ w/c ≤ 0.50) of portland cement, calcium aluminate cement, and weakly and strongly flocculated alumina (Φ0 = 0.20) using the centrifuge sediment height technique. Equilibrium sediment heights are reached quickly, allowing all measurements to be taken during the cement's induction period. The compressive behavior showed little dependence on the compressive history. Compressive yield stress was, however, dependent upon initial volume fraction, decreasing as the initial volume fraction increases. This behavior was observed in both the cements and alumina suspensions, implying that strong dependencies on initial structure may be a general property of the compressive behavior of flocculated suspensions.

Initiation of underwater granular avalanches: Influence of the initial volume fraction

2008 ◽  
Vol 20 (11) ◽  
pp. 111701 ◽  
Author(s):  
M. Pailha ◽  
M. Nicolas ◽  
O. Pouliquen
Keyword(s):  
Volume Fraction ◽  
Initial Volume ◽  
Initial Volume Fraction

Numerical Evaluation of Micro- to Macroscopic Mechanical Behavior of Plastic Foam

2007 ◽  
Vol 340-341 ◽  
pp. 1025-1030
Author(s):  
Isamu Riku ◽  
Koji Mimura
Keyword(s):  
Mechanical Behavior ◽  
Strain Hardening ◽  
Loading Condition ◽  
Volume Fraction ◽  
Plastic Foam ◽  
Uniform Compression ◽  
Initial Volume ◽  
Initial Volume Fraction ◽  
Characteristic Value ◽  
Initial Modulus

In this study, we employ the two-dimensional homogenization model based on molecular chain network theory to investigate the micro- to macroscopic mechanical behavior of plastic foam under macroscopic uniform compression. A parametric study is performed to quantify the effect of a characteristic value of matrix, distribution and initial volume fraction of voids, and the macroscopic triaxiality of loading condition on the deformation behavior of the foam. The results suggest that the onset of localized shear band at the ligament between voids together with the microscopic buckling of the ligament leads to the macroscopic yield of the foam. The initial modulus and the macroscopic yield stress of the foam have no dependence on the characteristic value of matrix. Furthermore, as the microscopic buckling of the ligament is promoted in case of high initial volume fraction of voids and high triaxiality loading condition, the macroscopic yield point appears at early deformation stage. After the macroscopic yield, macroscopic strain hardening appears in the macroscopic response and a remarkable strain hardening is shown in case of high initial volume fraction of voids and high triaxiality loading condition due to the considerable increase of the density of the foam in these cases.

Initiation of Submarine Granular Avalanches: Role of the Initial Volume Fraction

2008 ◽  
Author(s):  
Mickaël Pailha ◽  
Olivier Pouliquen ◽  
Maxime Nicolas ◽  
Albert Co ◽  
Gary L. Leal ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Initial Volume ◽  
Initial Volume Fraction

scholarly journals Granular collapse in a fluid: Role of the initial volume fraction

2011 ◽  
Vol 23 (7) ◽  
pp. 073301 ◽  
Author(s):  
L. Rondon ◽  
O. Pouliquen ◽  
P. Aussillous
Keyword(s):  
Volume Fraction ◽  
Initial Volume ◽  
Initial Volume Fraction ◽  
Granular Collapse

A two-phase flow description of the initiation of underwater granular avalanches

2009 ◽  
Vol 633 ◽  
pp. 115-135 ◽  
Author(s):  
MICKAËL PAILHA ◽  
OLIVIER POULIQUEN
Keyword(s):  
Critical State ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
State Theory ◽  
Phase Flow ◽  
Two Phase ◽  
Initial Volume ◽  
Initial Volume Fraction ◽  
Critical State Theory

A theoretical model based on a depth-averaged version of two-phase flow equations is developed to describe the initiation of underwater granular avalanches. The rheology of the granular phase is based on a shear-rate-dependent critical state theory, which combines a critical state theory proposed by Roux & Radjai (1998), and a rheological model recently proposed for immersed granular flows. Using those phenomenological constitutive equations, the model is able to describe both the dilatancy effects experienced by the granular skeleton during the initial deformations and the rheology of wet granular media when the flow is fully developed. Numerical solutions of the two-phase flow model are computed in the case of a uniform layer of granular material fully immersed in a liquid and suddenly inclined from horizontal. The predictions are quantitatively compared with experiments by Pailha, Nicolas & Pouliquen (2008), who have studied the role of the initial volume fraction on the dynamics of underwater granular avalanches. Once the rheology is calibrated using steady-state regimes, the model correctly predicts the complex transient dynamics observed in the experiments and the crucial role of the initial volume fraction. Quantitative predictions are obtained for the triggering time of the avalanche, for the acceleration of the layer and for the pore pressure.

scholarly journals Experimental demonstration of negative refraction with 3D locally resonant acoustic metafluids

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Benoit Tallon ◽  
Artem Kovalenko ◽  
Olivier Poncelet ◽  
Christophe Aristégui ◽  
Olivier Mondain-Monval ◽  
...  
Keyword(s):  
Experimental Data ◽  
Yield Stress ◽  
Multiple Scattering ◽  
Silicone Rubber ◽  
Acoustic Waves ◽  
Scattering Theory ◽  
Negative Refraction ◽  
Volume Fraction ◽  
Experimental Demonstration ◽  
Acoustic Beam

AbstractNegative refraction of acoustic waves is demonstrated through underwater experiments conducted at ultrasonic frequencies on a 3D locally resonant acoustic metafluid made of soft porous silicone-rubber micro-beads suspended in a yield-stress fluid. By measuring the refracted angle of the acoustic beam transmitted through this metafluid shaped as a prism, we determine the acoustic index to water according to Snell’s law. These experimental data are then compared with an excellent agreement to calculations performed in the framework of Multiple Scattering Theory showing that the emergence of negative refraction depends on the volume fraction $$\Phi$$ Φ of the resonant micro-beads. For diluted metafluid ($$\Phi =3\%$$ Φ = 3 % ), only positive refraction occurs whereas negative refraction is demonstrated over a broad frequency band with concentrated metafluid ($$\Phi =17\%$$ Φ = 17 % ).

scholarly journals Physicochemical, Mineralogical, and Mechanical Properties of Calcium Aluminate Cement Concrete Exposed to Elevated Temperatures

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3855
Author(s):  
Amirmohamad Abolhasani ◽  
Bijan Samali ◽  
Fatemeh Aslani
Keyword(s):  
Temperature Rise ◽  
Calcium Aluminate ◽  
Elevated Temperatures ◽  
Ultrasonic Pulse Velocity ◽  
Pulse Velocity ◽  
Calcium Aluminate Cement ◽  
Cement Concrete ◽  
Sem Images ◽  
Strength Deterioration ◽  
Aluminate Cement

One commonly used cement type for thermal applications is CAC containing 38–40% alumina, although the postheated behavior of this cement subjected to elevated temperature has not been studied yet. Here, through extensive experimentation, the postheated mineralogical and physicochemical features of calcium aluminate cement concrete (CACC) were examined via DTA/TGA, X-ray diffraction (XRD), and scanning electron microscopy (SEM) imaging and the variation in the concrete physical features and the compressive strength deterioration with temperature rise were examined through ultrasonic pulse velocity (UPV) values. In addition, other mechanical features that were addressed were the residual tensile strength and elastic modulus. According to the XRD test results, with the temperature rise, the dehydration of the C3AH6 structure occurred, which, in turn, led to the crystallization of the monocalcium dialuminate (CA2) and alumina (Al2O3) structures. The SEM images indicated specific variations in morphology that corresponded to concrete deterioration due to heat.

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