scholarly journals Evaluation of Cost-Effective Modified Binder Thin Chip and Cape Seal Surfacings on an Anionic Nano-Modified Emulsion (NME)-Stabilised Base Layer Using Accelerated Pavement Testing (APT)

2021 ◽  
Vol 11 (6) ◽  
pp. 2514
Author(s):  
Gerrit J. Jordaan ◽  
Wynand J. vd M. Steyn ◽  
Andre Broekman
Keyword(s):  
Cost Effective ◽  
Base Layer ◽  
Accelerated Pavement Testing ◽  
Modified Binders ◽  
Chip Seal ◽  
Load Simulator ◽  
Pavement Testing ◽  
Modified Binder ◽  
Design And Testing ◽  
Selection Of

Emulsion stabilisation of base layers surfaced with chip seals often proves problematic, with chips punching into the base and early distress. This can be aggravated by the use of modified binders that restricts the evaporation of moisture from pavement layers. The introduction of new-age (nano)-modified emulsion (NME) stabilisation has the advantage that water is chemically repelled from the stabilised layer, resulting in an accelerated development of strength. A need was identified to evaluate the early-life performance of selected chip and Cape seals, together with identified modified binders on anionic NME-stabilised base layers constructed with materials traditionally classified as unsuitable, using archaic empirically derived tests. Three different chip seal surfacings with unconventional modified binders were constructed and evaluated using accelerated pavement testing (APT) with the Model Mobile Load Simulator—3rd model (MMLS3). The objectives of the experimental design and testing were to evaluate the binder performance, chip seal performance in terms of early loss of chips before chip orientation, punching of the chips into the anionic NME-stabilised base and deformation characteristics of a Cape seal that was hand-laid using an anionic NME slurry without any cement filler. It was shown that that chip seal surfacings can be used at low risk, on a base layer containing materials with fines exceeding 22%. The selection of specific modified binders can reduce risks associated with chip seal surfacings, which can impact construction limitations. The recommended use of elastomer-modified binders on newly constructed or rehabilitated layers, resulting in moisture entrapment, needs to be reconsidered.

scholarly journals Evaluation of cost-effective thin modified binder seals on Nano-Modified Emulsion (NME) stabilised base layers using Accelerated Pavement Testing (APT)

2021 ◽  
Author(s):  
Gerrit J Jordaan ◽  
Wynand J VdM Steyn ◽  
Andre Broekman
Keyword(s):  
Cost Effective ◽  
Base Layer ◽  
Accelerated Pavement Testing ◽  
Modified Binders ◽  
Chip Seal ◽  
Standard Normal ◽  
Chip Seals ◽  
Pavement Testing ◽  
Modified Binder ◽  
Design And Testing

Emulsion stabilisation of base layers surfaced with chip seals often proves problematic with chips punching into the base and early distress. This can be aggravated by the use of modified binders that restricts the evaporation of moisture from pavement layers. The introduction of New-age (Nano) Modified Emulsion (NME) stabilisation has the advantage that water is chemically repelled from the stabilised layer resulting in an accelerated development of strength. A need was identified to evaluate the early life performance of selected chip seals, together with identified binders. Three different chip seal surfacings with unconventional modified binders were constructed and evaluated using Accelerated Pavement Testing (APT) with the MMLS3. The objectives of the experimental design and testing were to evaluate binder performance, early loss of chips before chip orientation at low temperatures, punching of the chips into the NME stabilised base, deformation characteristics of a Cape seal and the effect of the use of a standard normal modified binder. This paper contains details of the NME base layer, the binder and seal selection and the test results. It is shown that a cost-effective thin chip seal in combination with a suitable binder can be used on a NME stabilised base with confidence.

Prediction of Pavement Fatigue for California Department of Transportation Accelerated Pavement Testing Program Drained and Undrained Test Sections

1996 ◽  
Vol 1540 (1) ◽  
pp. 105-114
Author(s):  
Fenella Long ◽  
John Harvey ◽  
Clark Scheffy ◽  
Carl L. Monismith
Keyword(s):  
Fatigue Life ◽  
Laboratory Testing ◽  
Testing Procedure ◽  
Base Layer ◽  
Department Of Transportation ◽  
California Department ◽  
Accelerated Pavement Testing ◽  
Actual Performance ◽  
Pavement Structures ◽  
Pavement Testing

The use of laboratory testing and mechanistic analysis to predict the fatigue life of the California Department of Transportation accelerated pavement testing (CAL/APT) heavy vehicle simulator (HVS) test sections is investigated. Two pavement structures are investigated: a drained pavement that includes an asphalt-treated permeable base layer and an undrained conventional asphalt concrete pavement. The fatigue life under HVS accelerated loading for both sections is predicted using the laboratory testing procedure from SHRP A-003A, which is based on tests of actual pavement samples using the flexural fatigue beam test. This fatigue life is compared with predictions from the SHRP A-003A surrogate equation for flexural testing, the Shell model, and the Asphalt Institute model. The critical tensile strains for the fatigue calculations using the models investigated were determined using linear elastic theory. Ranges of moduli for the pavement layers were determined from extensive material testing, and 24 moduli combinations were made. The effect of pavement type, changes in moduli, and the HVS loading conditions on the tensile strain and fatigue life predictions between the models is discussed. Reasons for differences between predicted fatigue lives and their implications are also discussed. Predicted fatigue life is compared with actual performance under HVS loading for the drained pavement.

Detection and Monitoring of Cracks in Asphalt Pavement Under Texas Mobile Load Simulator Testing

1997 ◽  
Vol 1570 (1) ◽  
pp. 10-22 ◽  
Author(s):  
N.-K. J. Lee ◽  
F. Hugo ◽  
K. H. Stokoe
Keyword(s):  
Surface Layer ◽  
Longitudinal Direction ◽  
Main Mode ◽  
Accelerated Pavement Testing ◽  
Surface Cracking ◽  
Longitudinal Stiffness ◽  
Load Simulator ◽  
Surface Distress ◽  
Pavement Testing ◽  
Falling Weight

The Texas mobile load simulator (TxMLS) is a newly developed accelerated pavement testing device used to evaluate pavement performance under real trafficking loads. This evaluation is performed by applying trafficking loads and monitoring surface distress, such as cracking and rutting, in conjunction with a number of other measurements of the pavement, such as those conducted with the falling weight deflectometer, multidepth deflectometer, strain gauge, pressure cells, and seismic (stress-wave) tests. A procedure for monitoring the progressive degradation of the asphalt surface was developed using the spectral-analysis-of-surface-waves (SASW) technique. This procedure was applied with the TxMLS and proved to be equally effective. SASW tests that were performed intermittently between trafficking phases on trafficked and untrafficked areas show ( a) the effect of temperatures and frequencies on the asphalt moduli, ( b) the importance of temperature and frequency corrections in analyzing the degradation of the asphalt surface layer, and ( c) the long-term trends in surface-wave velocities (and hence, moduli) of the surface layer with increasing number of load applications. It was found that stiffness of the asphalt layer in the longitudinal direction was progressively reduced under trafficking. Concurrently, surface cracking progressively increased. The reduction in longitudinal stiffness occurred at a faster rate than the crack growth. In contrast, the reduction in the stiffness of the asphalt layer in the transverse direction was slower, probably because the main mode of cracking was transverse. The feasibility of using SASW testing as a predictor of degradation and imminent cracking was confirmed with these studies.

Rut Initiation Mechanisms in Asphalt Mixtures as Generated under Accelerated Pavement Testing

2005 ◽  
Vol 1940 (1) ◽  
pp. 136-145 ◽  
Author(s):  
Salil Gokhale ◽  
Bouzid Choubane ◽  
Tom Byron ◽  
Mang Tia
Keyword(s):  
Asphalt Mixtures ◽  
Department Of Transportation ◽  
Accelerated Pavement Testing ◽  
Subsequent Investigation ◽  
Florida Department ◽  
Vehicle Simulator ◽  
Pavement Testing ◽  
Modified Binder ◽  
Styrene Butadiene ◽  
Heavy Vehicle Simulator

The Florida Department of Transportation (FDOT) conducted an experiment to address the effects of polymer modifiers on the performance of Superpave® mixes by using a heavy vehicle simulator. Two fine-graded Superpave mixes were considered. One mix included a virgin binder meeting the requirements of PG 67-22, and the other contained a styrene– butadiene–styrene polymer (SBS)-modified binder meeting those of PG 76-22. Both respective mixes contained the same effective binder content, aggregate components, and gradation. The mixes were designed for 10 million to 30 million equivalent single-axle loads with the use of the standard Superpave mix design methodology. During placement of these mixes, all standard FDOT density requirements and acceptance criteria were applicable. The subsequent investigation showed that the sections with SBS-modified mixture significantly outperformed those with the unmodified mixture. It was also determined that rutting in the unmodified mixture was primarily a function of shear flow, whereas rutting in the SBS-modified mixture was caused mainly by densification. This paper presents a description of the testing program, the data collection effort, and the subsequent analyses and findings, focusing primarily on the initiation mechanisms of rutting in asphalt mixtures as generated and observed under accelerated pavement testing.

Performance of CAL/APT Drained and Undrained Pavements Under HVS Loading

1998 ◽  
Vol 1615 (1) ◽  
pp. 11-20 ◽  
Author(s):  
J. Harvey ◽  
L. Louw ◽  
I. Guada ◽  
D. Hung ◽  
C. Scheffy
Keyword(s):  
Asphalt Concrete ◽  
Design Method ◽  
Surface Profile ◽  
Design Procedure ◽  
Base Layer ◽  
California Department ◽  
Accelerated Pavement Testing ◽  
Pavement Testing ◽  
Fatigue Crack Development ◽  
And Performance

The Heavy Vehicle Simulator (HVS) test results of the first experiment of the California Department of Transportation (Caltrans) Accelerated Pavement Testing Program, known as CAL/APT, are presented. The Goal 1 experiment was designed to validate the existing Caltrans pavement thickness design method for drained (containing an asphalt treated permeable base layer) and undrained (containing aggregate base only) flexible pavements. The pavement performance results include fatigue crack development, surface profile, and vertical deflections. The observed performance of the two types of structures is compared. The effects of construction compaction of the asphalt concrete, bonding between asphalt concrete lifts, the relative performance of the drained and undrained structures under the controlled HVS environment, and comparison of the observed performance and performance expected by the thickness design procedure are presented and discussed.

Accelerated Pavement Testing to Evaluate the Reinforcement Effect of Geogrids in Flexible Pavements

2020 ◽  
Vol 2674 (10) ◽  
pp. 134-145
Author(s):  
Bingye Han ◽  
Pawel Polaczyk ◽  
Hongren Gong ◽  
Rong Ma ◽  
Yuetan Ma ◽  
...  
Keyword(s):  
Permanent Deformation ◽  
Flexible Pavements ◽  
Performance Testing ◽  
Base Layer ◽  
Reinforcement Effect ◽  
Accelerated Pavement Testing ◽  
Forensic Evaluations ◽  
Base Course ◽  
Pavement Testing ◽  
Response Testing

This study presents an accelerated pavement testing (APT) to evaluate the reinforcement effect of geogrids in flexible pavements. A full-scale conventional three-layer flexible pavement structure was constructed, and was divided into one unreinforced section and two reinforced sections with base reinforced by geogrids placed at different depth of base course. The testing program was divided into three parts: performance testing, response testing, and forensic evaluations. The performance testing recorded the development of surface permanent deformation with the number of loadings. The falling weight deflectometer (FWD) was employed to investigate deflections and moduli of flexible pavements in the response testing. The excavation of pavements was to further analyze reinforcement mechanisms. Test results demonstrated the benefits of incorporating geogrids in base course in reducing the permanent deformation and improving the modulus of base course. Compared with the unreinforced section, accumulated permanent deformations in the two reinforced sections decreased significantly, with a drop of 13%–37%, and the back-calculated moduli of the reinforced base increased by 58%–78% after APT. It was possible that sufficient permanent deformation was needed for mobilizing geogrids to constrain lateral movements of granular particles, to increase the overall structural behavior of the reinforced base course, and to improve the stress distribution on the subgrade. These interaction mechanisms were also confirmed in the pavement trench. For a pavement system consisting of a thin surface and base layer, the proper placement position of geogrids was at the base–subgrade interface for this test and loading arrangement.

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