Permanent deformation response parameters of asphalt mixtures for a new mix-confined repeated load test

2013 ◽  
Vol 20 (5) ◽  
pp. 1434-1442 ◽  
Author(s):  
Gong-yun Liao ◽  
Yi-wen Yang ◽  
Xiao-ming Huang ◽  
Jin-yuan Xiang
Keyword(s):  
Permanent Deformation ◽  
Asphalt Mixtures ◽  
Load Test ◽  
Deformation Response ◽  
Repeated Load

Preliminary Field Validation of Simple Performance Tests for Permanent Deformation: Case Study

2003 ◽  
Vol 1832 (1) ◽  
pp. 209-216 ◽  
Author(s):  
Fujie Zhou ◽  
Tom Scullion
Keyword(s):  
Dynamic Modulus ◽  
Permanent Deformation ◽  
Mixture Design ◽  
Asphalt Mixtures ◽  
Load Test ◽  
Performance Tests ◽  
Field Validation ◽  
Dynamic Modulus Test ◽  
Repeated Load

Simple performance tests (SPTs) to be used with the Superpave® volumetric mixture design procedure were recently recommended by NCHRP Project 9-19 (Simple Performance Test for Superpave Mix Design). Field validation of the SPTs is critical to their final acceptance and implementation in Superpave mixture design practice. Special Pavement Studies-1 (SPS-1) prematurely rutted sections on US-281 in Texas were used to validate the SPTs for permanent deformation, including the dynamic modulus test and repeated-load test and associated rutting indicators E*/sin δ and flow number ( F n), respectively. The results of this case study clearly show that both the dynamic modulus test and E*/sin δ and the repeated-load test and F n can effectively distinguish the good mixtures from the bad. Compared with E*/sin δ, F n can better differentiate the performance of asphalt mixtures. These results preliminarily validated both SPTs for permanent deformation. In addition, the location of the tertiary point in the plot of permanent strain versus number of load repetitions is clarified; a simple linear model needs to be added in order to determine the F n. Furthermore, the possibility of using the number of load repetitions ( Nps) corresponding to the initial point of the secondary stage to characterize the rutting resistance of asphalt mixtures is discussed. The new indicator proposed is supported by the limited data presented in this paper and can be easily determined and can reduce test duration significantly.

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.

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.

Characterization of Permanent Deformation of Asphalt Mixtures with Minimum Strain Rate, LVECD Program, and Triaxial Stress Sweep Test

2017 ◽  
Vol 2631 (1) ◽  
pp. 96-104 ◽  
Author(s):  
Dahae Kim ◽  
Y. Richard Kim
Keyword(s):  
Permanent Deformation ◽  
Single Layer ◽  
Asphalt Mixtures ◽  
Triaxial Stress ◽  
Structural Level ◽  
Flow Number ◽  
Specific Test ◽  
Rutting Resistance ◽  
Testing Effort ◽  
Repeated Load

The rutting resistance of asphalt concrete is typically assessed by using flow number tests in the lab in accordance with AASHTO TP 79. However, the flow number represents the rutting resistance of the material with regard to ranking for only a specific test condition. A significant amount of testing effort is needed to evaluate rutting resistance by using the flow number test under various loading conditions and temperatures. Therefore, researchers have developed alternative test methods to reduce the testing effort. For example, the incremental repeated-load permanent deformation test and the triaxial stress sweep (TSS) test are two promising protocols that can predict the permanent deformation of asphalt mixtures efficiently and accurately. This study compares the minimum strain rates (MSRs) obtained from incremental repeated-load permanent deformation and TSS tests to examine the ability of the TSS test to analyze the MSRs of asphalt mixtures. In addition, the viscoplastic shift model calibrated from the TSS test that is implemented in the layered viscoelastic pavement analysis for critical distresses (LVECD) program was used to predict the rut depths of 16 pavement sections from four sources. The MSRs and rut depths predicted from the LVECD program were compared with actual measured rut depths. The results of this study indicated that the MSR results could only be used to rank the rutting susceptibility of single-layer asphalt pavements. For a multilayered pavement system, structural level analysis is necessary to predict the accurate rutting performance and rut depths of the test sections.

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