STRESS RELAXATION MODULUS OF EPOXY ASPHALT MIXTURE

An experimental measurement of dynamic properties, including dynamic modulus and phase angle, of asphalt mixtures with varying saturation levels of moisture has been carried out in the study. The specimens of asphalt mixture were compacted with three different air void contents and two different levels of moisture saturation. The relaxation modulus expressed by Prony series was estimated from the Prony series expression of dynamic modulus. The purpose of this study is to identify the effect of air voids on dynamic properties that affect and control moisture susceptibility of asphalt mixtures and then compare the stress relaxation behavior of asphalt mixtures between dry and moisture conditioning. The results show that dynamic properties are quite sensitive to temperature and loading frequency in dry and different saturation levels of moisture. Moreover, and the smaller the air voids and saturation level, the greater the increase in dynamic modulus and rate of stress relaxation, indicating better resistance to cracking and less moisture susceptibility.

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Evaluation of the Effects of Filler Fineness on the Properties of an Epoxy Asphalt Mixture

Materials ◽

10.3390/ma14082003 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2003

Author(s):

Wei Xu ◽

Jintao Wei ◽

Zhengxiong Chen ◽

Feng Wang ◽

Jian Zhao

Keyword(s):

Particle Size ◽

Average Particle Size ◽

Asphalt Mixture ◽

Average Particle ◽

Fine Dust ◽

Bonding Structure ◽

Epoxy Asphalt ◽

Mineral Powder ◽

Marshall Stability ◽

Mixture Sample

The type and fineness of a filler significantly affect the performance of an asphalt mixture. There is a lack of specific research on the effects of filler fineness and dust from aggregates on the properties of epoxy asphalt (EA) mixtures. The effects of aggregate dust and mineral powder on the properties of an EA mixture were evaluated. These filler were tested to determine their fineness, specific surface area and mineral composition. The effects of these fillers on the EA mastic sample and mixture were evaluated. The morphology of the EA mastic samples was analyzed using scanning electron microscopy (SEM). The effects of the fillers on the Marshall stability, tensile strength and fatigue performance of the EA mixture were evaluated. The dust from the aggregates exhibited an even particle size distribution, and its average particle size was approximately 20% of that of the mineral powder. The SEM microanalysis showed that the EA mastic sample containing relatively fine dust formed a tight and dense interfacial bonding structure with the aggregate. The EA mixture sample containing filler composed of dust from aggregate had a significantly higher strength and longer fatigue life than that of the EA sample containing filler composed of mineral powder.

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STRESS RELAXATION OF MAGNETORHEOLOGICAL FLUIDS

International Journal of Modern Physics B ◽

10.1142/s0217979202012803 ◽

2002 ◽

Vol 16 (17n18) ◽

pp. 2655-2661

Author(s):

W. H. LI ◽

G. CHEN ◽

S. H. YEO ◽

H. DU

Keyword(s):

Stress Relaxation ◽

Viscoelastic Model ◽

Relaxation Modulus ◽

Damping Function ◽

Mr Fluids ◽

Large Step ◽

Linear Viscoelastic ◽

Predicted Values ◽

Two Parameters ◽

Step Strain

In this paper, the experimental and modeling study and analysis of the stress relaxation characteristics of magnetorheological (MR) fluids under step shear are presented. The experiments are carried out using a rheometer with parallel-plate geometry. The applied strain varies from 0.01% to 100%, covering both the pre-yield and post-yield regimes. The effects of step strain, field strength, and temperature on the stress modulus are addressed. For small step strain ranges, the stress relaxation modulus G(t,γ) is independent of step strain, where MR fluids behave as linear viscoelastic solids. For large step strain ranges, the stress relaxation modulus decreases gradually with increasing step strain. Morever, the stress relaxation modulus G(t,γ) was found to obey time-strain factorability. That is, G(t,γ) can be represented as the product of a linear stress relaxation G(t) and a strain-dependent damping function h(γ). The linear stress relaxation modulus is represented as a three-parameter solid viscoelastic model, and the damping function h(γ) has a sigmoidal form with two parameters. The comparison between the experimental results and the model-predicted values indicates that this model can accurately describe the relaxation behavior of MR fluids under step strains.

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Effect of Cure State on Stress Relaxation in 3501-6 Epoxy Resin

Journal of Engineering Materials and Technology ◽

10.1115/1.2812254 ◽

1997 ◽

Vol 119 (3) ◽

pp. 262-265 ◽

Cited By ~ 7

Author(s):

S. R. White ◽

A. B. Hartman

Keyword(s):

Stress Relaxation ◽

Epoxy Resin ◽

Creep Compliance ◽

Numerical Technique ◽

Matrix Material ◽

Relaxation Modulus ◽

Master Curves ◽

Creep Tests ◽

Three Point Bending ◽

Direct Inversion

Little experimental work has been done to characterize how the viscoelastic properties of composite material matrix resins develop during cure. In this paper, the results of a series of creep tests carried out on 3501–6 epoxy resin, a common epoxy matrix material for graphite/epoxy composites, at several different cure states is reported. Beam specimens were isothermally cured at increasing cure temperatures to obtain a range of degrees of cure from 0.66 to 0.99. These specimens were then tested in three-point bending to obtain creep compliance over a wide temperature range. The master curves and shift functions for each degree of cure case were obtained by time-temperature superposition. A numerical technique and direct inversion were used to calculate the stress relaxation modulus master curves from the creep compliance master curves. Direct inversion was shown to be adequate for fully cured specimens, however it underpredicts the relaxation modulus and the transition for partially cured specimens. Correlations with experimental stress relaxation data from Kim and White (1996) showed that reasonably accurate results can be obtained by creep testing followed by numerical conversion using the Hopkins-Hamming method.

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A Direct Experimental Determination of the Elastic Contribution of Chain Entangling in a Tightly Crosslinked Elastomer

Rubber Chemistry and Technology ◽

10.5254/1.3535875 ◽

1982 ◽

Vol 55 (1) ◽

pp. 62-65

Author(s):

W. Batsberg ◽

O. Kramer

Keyword(s):

Stress Relaxation ◽

Elastic Equilibrium ◽

Relaxation Modulus ◽

Chain Scission ◽

Experimental Result ◽

Strained State ◽

Equilibrium Stress ◽

Linear Chains ◽

Network Methods

Abstract The experimental result, that the equilibrium force is nearly equal to the pseudoequilibrium force immediately prior to quenching and irradiation, allows the following conclusions: (1) Chain scission during crosslinking is not a serious problem. (2) The network of highly entangled linear chains is effectively at elastic equilibrium immediately prior to crosslinking in the strained state. This would not be the case if the entangled structure remained untrapped. (3) The effect of chain entangling in tightly crosslinked elastomers is large, also at elastic equilibrium. In fact, it is almost quantitatively equal to the pseudo-equilibrium stress relaxation modulus of the uncrosslinked linear polymer. This result is in agreement with the results from the Langley and the two-network methods.

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