Permanent Deformation of Steel under Slowly Repeated Load

1954 ◽  
Vol 3 (15) ◽  
pp. 314-317
Author(s):  
Minoru KAWAMOTO ◽  
Tadakazu SAKURAI ◽  
Morio SEKI
Keyword(s):  
Permanent Deformation ◽  
Repeated Load

Performance of Virginia’s Early Foamed Warm Mix Asphalt Mixtures

2018 ◽  
Vol 2672 (28) ◽  
pp. 178-189 ◽  
Author(s):  
Stacey D. Diefenderfer
Keyword(s):  
Dynamic Modulus ◽  
Permanent Deformation ◽  
Warm Mix Asphalt ◽  
Department Of Transportation ◽  
High Dynamic ◽  
Repeated Load ◽  
And Performance ◽  
Virginia Department ◽  
Performance Grading ◽  
Air Void

The Virginia Department of Transportation began allowing the use of warm mix asphalt (WMA) in 2008. Although several WMA technologies were investigated prior to implementation, foamed WMA was not. This study evaluated the properties and performance of foamed WMA placed during the initial implementation of the technology to determine whether the technology had performed as expected. Six mixtures produced using plant foaming technologies and placed between 2008 and 2010 were identified and subjected to field coring and laboratory testing. Coring was performed in 2014, resulting in pavement ages from 4 to 6 years. Three comparable hot mix asphalt (HMA) mixtures were cored at 5 years for comparison. Cores were evaluated for air-void contents and permeability and were subjected to dynamic modulus, repeated load permanent deformation, and overlay testing. In addition, binder was extracted and recovered for performance grading. Similar properties were found for the WMA and HMA mixtures. One WMA mixture had high dynamic modulus and binder stiffness, but overlay testing did not indicate any tendency for premature cracking. All binders had aged between two and three performance grades above that specified at construction. WMA binders and one HMA binder aged two grades higher, and the remaining two HMA binders aged three grades higher, indicating a likely influence on aging of the reduced temperatures at which the early foamed mixtures were typically produced. Overall results indicated that foamed WMA and HMA mixtures should be expected to perform similarly.

Expedited Testing Program for Performance Characterization of Asphalt Mixtures

2019 ◽  
Vol 2673 (12) ◽  
pp. 225-233
Author(s):  
Intikhab Haidar ◽  
Charles W. Schwartz ◽  
Sadaf Khosravifar
Keyword(s):  
Permanent Deformation ◽  
Performance Testing ◽  
Testing Procedure ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Test Specifications ◽  
Research Grade ◽  
Repeated Load ◽  
Lengthy Process

The past two decades have seen significant efforts to standardize a series of simplified test methods to characterize the dynamic modulus (DM) and repeated load permanent deformation (RLPD) performance characteristics of asphalt mixtures using the asphalt mixtures performance tester (AMPT). While the current AASHTO T 79 test specifications for the AMPT are faster and easier to perform than their preceding research grade test protocols, there is still reluctance among highway agencies and industry to conduct performance testing using the AMPT. One significant reason is the lengthy process of sample preparation and testing for the DM and RLPD tests. Two studies to expedite this process are reported here. First, the potential for abbreviating the DM testing procedure was examined. It provides the option to fully exclude testing at 40°C by adding an additional frequency of 0.01 Hz at 20°C. This approach reduces time for testing as well as for sample conditioning at high temperature. Second, the possibility of reducing the total number of required specimens was evaluated. The variation of the DM under repetitive testing and the appropriateness of performing the RLPD test on samples already tested for DM were evaluated. The results showed that specimen damage or densification because of DM testing is insignificant. As a consequence, DM test specimens can be re-used for RLPD testing, reducing the required number of samples from 12 to 9.

Experimental Study on Permanent Deformation of Fine Sandy Subgrade Filling in Coastal Region

2019 ◽  
Vol 814 ◽  
pp. 419-424
Author(s):  
Ding Zhou
Keyword(s):  
Water Content ◽  
Permanent Deformation ◽  
Coastal Region ◽  
Fine Sand ◽  
Test Method ◽  
Factors Affecting ◽  
Permanent Strain ◽  
Shaped Particle ◽  
Repeated Load ◽  
Performance Analyze

By using repeated load triaxial test method, test results of permanent strain of fine sand were obtained. The main factors affecting permanent strain of fine sand samples are water content, degree of compaction and deviator stress. Permanent strain of sand is less sensitive to moisture when compared to clay and silt. Well compacted fine sand subgrade is less affected by the change of water content, which illustrates a more stable long-term performance. Analyze from meso-structure, the ellipsoid shaped particle is less stable than sphere shaped one under the effect to repeated load. Fine sand with smaller amount of ellipsoid shaped particle would have better dynamic behaviors. Predicting models of permanent strain with basic soil physical properties were established using regression analysis.

Repeated compressive loading of a sand

1979 ◽  
Vol 16 (4) ◽  
pp. 798-802 ◽  
Author(s):  
P. N. Gaskin ◽  
G. P. Raymond ◽  
F. Y. Addo-Abedi ◽  
J. S. Lau
Keyword(s):  
Threshold Stress ◽  
Resilient Modulus ◽  
Permanent Deformation ◽  
Compressive Loading ◽  
Triaxial Tests ◽  
Failure Strength ◽  
Stress Cycles ◽  
Repeated Load ◽  
Static Failure

Twelve repeated load drained triaxial tests to at least 105 cycles on a sand are reported. A threshold stress of about 50% of the static failure strength was found. Below the threshold stress, the permanent deformation and resilient modulus reached constant values. Above the threshold stress, the permanent deformation began to increase rapidly and the resilient modulus to decrease as the number of stress cycles increased. The importance of keeping the traffic stress in the pavement below the threshold stress is outlined.

Numerical and Graphical Method to Assess Permanent Deformation Potential for Repeated Compressive Loading of Asphalt Mixtures

2000 ◽  
Vol 1723 (1) ◽  
pp. 150-158 ◽  
Author(s):  
Rajesh K. Bhairampally ◽  
Robert L. Lytton ◽  
Dallas N. Little
Keyword(s):  
Strain Energy ◽  
Graphical Method ◽  
Permanent Deformation ◽  
Compressive Loading ◽  
Hydrated Lime ◽  
Numerical Approach ◽  
Empirical Models ◽  
Asphalt Mixtures ◽  
Deformation Potential ◽  
Repeated Load

Repeated-load permanent deformation testing has long been a popular way to characterize the performance of asphalt mixtures and to account for damage that leads to rutting. A number of empirical models have been used to fit repeated-load permanent deformation data. One such model, developed by Tseng and Lytton in 1989, fits permanent deformation data of most asphalt mixtures well. However, some mixtures exhibit a rate of damage that is in excess of that predicted by the 1989 Tseng and Lytton model. A numerical adaptation of the Tseng and Lytton empirical model is presented that readily characterizes such damage-susceptible mixtures. The excessive rate of damage is explained and reconciled in terms of plastic work theory and dissipated strain energy. The numerical approach is used to demonstrate the corrective effects of two types of additives to the mixtures: a recycled coproduct and hydrated lime.

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