Innovative Assessment Tests and Indicators for Performance-based Asphalt Mix Design

Innovative Assessment Tests and Indicators for Performance-based Asphalt Mix Design
Author: Hamza Alkuime
Publisher:
Total Pages: 626
Release: 2019
Genre: Pavements, Asphalt
ISBN:

Asphalt mixes are designed to provide adequate resistance to various distresses including cracking, rutting, and moisture damage. Recently, more efforts are directed towards including performance assessment tests during the design and production of asphalt mixes. Performance-Engineered Mix Design (PEMD) or Balanced Mix Design (BMD) is a new and innovative design approach that incorporates performance assessment tests to optimize the design of asphalt mixes to provide adequate performance. Although transportation agencies are motivated to implement the PEMD approach, several research knowledge gaps and concerns need to be addressed before PEMD successful implementation. This research study aims to advance, develop, and implement performance-engineered design approach and specifications to extend the service life of asphalt pavements.The first phase of this research developed and evaluated a new and innovative monotonic cracking performance indicator called Weibull Cracking Resistance Index (WeibullCRI). The proposed indicator describes the entire load-displacement curve, which overcomes the limitations of the existing performance indicators. First, WeibullCRI was examined using an extensive laboratory evaluation of 16 different asphalt mixes. The results indicated that WeibullCRI was sensitive to variation in binder content and binder PG and the results were in good agreement with the expected cracking resistance based on the composition of the studied mixes. In addition, WeibullCRI had low variability in test results and higher number of various statistical groups. Next, the applicability of WeibullCRI as a unified approach to analyze the results of various monotonic assessment tests was investigated using data generated by other researchers and reported in the literature. The results indicated that WeibullCRI is able to interpret the testing results of various monotonic performance assessment tests (i.e., IDT- intermediate temperature, Semi-Circle Bending [SCB]- intermediate temperature, SCB-low temperature, Disk-Shaped Compact Tension [DCT], and Simple Punching Shear Test [SPST]) and various displacement measurement methods (i.e., actuator vertical displacement and Crack Mouth Opening Displacement [CMOD]). WeibullCRI was also sensitive to variation in test conditions (i.e., specimen notch depth, thickness, and air void content) and mix composition proportions (i.e., binder content, binder grade, aggregate type, NMAS, aging, rejuvenator dosages, and Recycled Asphalt Pavement [RAP] materials).The second phase of this study reviewed and evaluated the current monotonic cracking performance assessment tests and indicators including the developed WeibullCRI used to assess asphalt mix resistance to cracking. In this phase, the testing requirements of various test standards, key publications, concepts, calculation methods, physical meaning, and advantages and disadvantages of various performance indicators were reviewed. Then, the study investigated the validity of the most promising testing standards and indicators. Three testing standards and 12 performance indicators were considered. Several aspects were examined including 1) investigate the fundamental meaning of the variation in the load-displacement curve in terms of the change in mix resistance to cracking, 2) sensitivity of performance indicators to mix compositions, 3) variability in test results, 4) number of various statistical groups, 5) correlation between various performance indicators, 6) direct correlation between laboratory results of monotonic performance tests and indicators with the observed field cracking, and 7) ability to develop PEMD specifications. A comprehensive laboratory investigation was conducted using 33 different asphalt mixes included six Laboratory Mixed-Laboratory Compacted (LMLC) and 10 Plant Mixed-Laboratory Compacted (PMLC) asphalt mixes, and 17 field projects with known cracking performance. The results showed that WeibullCRI calculated from the IDT test to have the lowest test variability, maximum number of Tukey's honestly significant difference (HSD) groups, and have excellent correlation with cyclic cracking resistance assessment indicators as compared to the other monotonic performance indicators. In addition, the results demonstrated that there was no direct correlation between all monotonic performance indicators and the observed field cracking performance, therefore an alternative approach was proposed, evaluated, and validated to develop performance thresholds for the selected performance indicators. Three pass/fail cracking performance thresholds were proposed for WeibullCRI to distinguish between asphalt mixes with good, fair, and poor cracking resistance using the proposed approach.The third phase of this study focused on the development and evaluation of a new cyclic cracking assessment test called Multi-Stage Semi-circle bending Dynamic (MSSD). The test offers advantages over the available monotonic and dynamic cracking assessment tests and addresses major concerns to implement the PEMD (i.e., performance test validity, complex specimen preparation, and testing time). The developed MSSD test simulates the repeated loading (cyclic) in a reasonable testing time (less than 9 hours per test regardless of mix type), has a fixed loading sequence that works for mixes with different characteristics (e.g., mix composition, percent air void content, thickness, etc.), and utilizes testing equipment and specimen geometry similar to that used in monotonic tests. The laboratory evaluation results showed that the proposed test and its derived performance indicators were sensitive to mix composition and had lower variability compared to other dynamic tests. In addition, the MSSD performance indicators correlated well with the observed cracking performance in the field and were able to distinguish between projects with good and poor resistance to cracking. Based on the evaluation results, three pass/fail cracking performance thresholds were proposed to distinguish between asphalt mixes with good, fair, and poor resistance to cracking.The fourth phase of this research examined the most promising tests and performance indicators to evaluate the resistance of asphalt mixtures to rutting. Two tests (i.e., Hamburg Wheel Tracking test [HWTT], and Asphalt Pavement Analyzer [APA] rut test) and three rutting performance indicators (i.e., HWTT rut depth after 15,000 passes [HWTT15000], HWTT rut depth at 20,000 passes [HWTT20000], and APA rut depth after 8,000 cycles [APA8000]) were considered. An intensive laboratory investigation was conducted that included six LMLC, 10 PMLC, and field cores extracted from 17 field projects. The research findings showed that both HWTT and APA rut test provided similar rutting assessment for the evaluated mixes. The study recommended using the HWTT over the APA rut test since HWTT can be also used to assess the resistance of asphalt mixtures to moisture damage to moisture damage. Also, the study recommended using HWTT15000 over HWTT20000 as a performance indicator since it requires less testing time.The final phase of this research provided recommendations of the best testing standards, performance indicators, and performance specifications to assess asphalt mix resistance to cracking and rutting. In addition, it provided guidelines to demonstrate the use of the proposed tools during the design and/or production of asphalt mixes. It also proposed standards testing procedures for the newly developed WeibullCRI performance indicator and MSSD test.

Development of Performance Based Test Procedures for Asphalt Mixtures

Development of Performance Based Test Procedures for Asphalt Mixtures
Author: Julie E. Kliewer
Publisher:
Total Pages: 450
Release: 1994
Genre: Aggregates (Building materials)
ISBN:

In 1987, Congress authorized a 5 year $150 million dollar research program called the Strategic Highway Research Program (SHRP). SHRP was divided into four major areas, including the asphalt research program. The asphalt research program was divided into six major research contracts, one such contract, SHRP-003A was called Performance Related Testing and Measuring of Asphalt Aggregate Interaction and Mixtures. Oregon State University performed the portion of this contract related to the development and validation of accelerated test procedures for aging, low temperature cracking, and moisture sensitivity of asphalt-aggreagte mixtures. This thesis contains five independent papers that discuss elements of the development, validation, and or implementation of these accelerated test procedures. In the first paper, the relationship between field performance and laboratory aging properties of asphalt-aggregate mixtures is discussed, including the relative importance of asphalt binder and aggregate type on the amount of aging experience. Based on this work recommended aging procedures are presented to simulate different environmental conditions and pavement age. The second paper makes use of the large body of resilient modulus data conducted as part of the SHRP research effort to compare data obtain in the diametral and the triaxial mode. It is not possible to give a relationship between triaxial and diametral resilient modulus, without describing specimen geometry and other test conditions. The third paper discusses the effect of aging on the thermal cracking properties of asphalt-aggregate mixtures. The temperature at which aging occurs affects the way cold temperature fracture properties change with time. Low temperatures result in quenching of the aging process, while high temperatures result in continued aging. The fourth paper discusses work conducted in association with the Oregon Department of Transportation to extend the environmental conditioning system (ECS) test procedure for moisture assessment to open graded mixtures. Comparison in the ECS of mixtures with and without anti-strip agents added indicates that they don't always decrease moisture damage potential. The final paper presents a discussion of asphalt chemistry and its relationship to asphalt-aggregate mixture performance. Using the SHRP asphalt model, aging and low temperature performance data collected at Oregon State University is explained.

Development of a Friction Performance Test for Compacted Asphalt Mixtures

Development of a Friction Performance Test for Compacted Asphalt Mixtures
Author: Rebecca S. McDaniel
Publisher:
Total Pages:
Release: 2018-03
Genre:
ISBN: 9781622605118

In a previous JTRP project published in 2010, Identification of Laboratory Techniques to Optimize Superpave HMA Surface Friction Characteristics, a laboratory procedure to polish and test the frictional properties of asphalt mixtures was developed. Subsequently, the procedure has been used in other research efforts to evaluate the frictional properties of recycled asphalt pavement (RAP) and local (possibly marginal) aggregate blends and for other testing purposes. Most notably, the procedure has been developed into Indiana Test Method (ITM) 221, "Acceptance Procedures for HMA Surface Mixture Coarse Aggregates for ESAL ¿10,000,000." The method requires compaction, polishing and testing of 500 mm by 500 mm (20 in. by 20 in.) square slabs of asphalt mix. This research project was initiated based to explore the possibility of expanding use of the lab polishing/testing procedure to test gyratory specimens or field cores. It was envisioned that such a method could be used during mix design as a check on potential frictional properties and/or as a quality acceptance test. A means of fabricating a circular test ring from seven cylindrical specimens was developed and used to test five different plant produced mixtures. Comparisons of ITM 221 slabs, gyratory specimens compacted to different air void contents and field cores showed cylindrical specimens could yield similar results to the accepted slab test method.

Simple Performance Tests

Simple Performance Tests
Author: Matthew W. Witczak
Publisher: Transportation Research Board
Total Pages: 25
Release: 2005
Genre: Pavements
ISBN: 0309088437

"Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration."

Engineering Properties of Asphalt Mixtures and the Relationship to Their Performance

Engineering Properties of Asphalt Mixtures and the Relationship to Their Performance
Author: Gerald A. Huber
Publisher: ASTM International
Total Pages: 237
Release: 1995
Genre: Asphalt emulsion mixtures
ISBN: 0803120028

Thirteen papers presented at the conference on [title], held in Phoenix, Arizona, December, 1994, discuss the products of the strategic highway research program, the Superpave method of mix design, and test methods for fatigue cracking and permanent deformation. Lacks an index. Annotation c. by Book

Precision of the Dynamic Modulus and Flow Number Tests Conducted with the Asphalt Mixture Performance Tester

Precision of the Dynamic Modulus and Flow Number Tests Conducted with the Asphalt Mixture Performance Tester
Author: Ramon Francis Bonaquist
Publisher: Transportation Research Board
Total Pages: 211
Release: 2011
Genre: Technology & Engineering
ISBN: 0309213363

TRB’s National Cooperative Highway Research Program (NCHRP) Report 702: Precision of the Dynamic Modulus and Flow Number Tests Conducted with the Asphalt Mixture Performance Tester describes the development of precision statements for the dynamic modulus and flow number tests conducted with the Asphalt Mixture Performance Tester.