Estimation of Resilient Modulus of Unbound Aggregates Using Performance-Related Base Course Properties

LTRC is conducting a research project to determine the seasonal variation of subgrade resilient modulus (MR) in an effort to implement PavementME. One objective of that project, which is presented in this paper, was to locally calibrate the Enhanced Integrated Climate Model’s (EICM Fenv) curve for seasonal subgrade MR changes. Shelby tube sampling was conducted on six different roadways to a depth of approximately 7.92 m beneath the shoulder pavement’s base course. The AASHTO T-99 MR test method was used on all samples with an additional eight specimens being tested with NCHRP 1–28A MR test method. Four soils from Louisiana which were not from the six roadways were also tested and included in the analyses. Once the MR tests were completed and plotted, it was noticed that there was a rather large scatter (R2 = −0.266) around the EICM Fenv curve. The authors hypothesized that this occurred due to the density differences between in situ and remolded specimens. Further analyses confirmed this hypothesis. LTRC developed a new method based on the EICM Fenv method to determine the relationship between changes in subgrade MR as a function of changes in moisture content with the in situ moisture content and MR used as the control. This method differs from the EICM Fenv in that the EICM Fenv uses optimum moisture content as the controlling parameter. The LTRC method can be used for design purposes as well as level 2 inputs into the EICM.

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Evaluation of the influence of compaction energy on the resilient behavior of lateritic soil in the field and laboratory

Soils and Rocks ◽

10.28927/sr.2021.071321 ◽

2021 ◽

Vol 44 (4) ◽

pp. 1-14

Author(s):

Paula Pascoal ◽

Amanda Sagrilo ◽

Magnos Baroni ◽

Luciano Specht ◽

Deividi Pereira

Keyword(s):

Resilient Modulus ◽

Chemical Characterization ◽

Correlation Coefficients ◽

Lateritic Soil ◽

Triaxial Tests ◽

Optimum Water Content ◽

Compaction Energy ◽

Base Course ◽

Physical And Chemical ◽

Resilient Behavior

This article presents the study of the resilient behavior of three soil horizons from a deposit of lateritic soil employed in a pavement structure in Rio Grande do Sul, Brazil. The use of lateritic soils in pavement layers is a common practice in Brazil and due to its peculiarities, its behavior must be investigated. The methodology consisted of physical and chemical characterization and resilient modulus determination. Samples from the three horizons, compacted at standard, intermediate and modified energy, were analyzed. In addition, undisturbed samples extracted from the interior and top layer of the embankment were submitted to repeated load triaxial tests for resilient modulus determination. The results indicated that the soil exhibit good behavior for pavement subgrade applications, perhaps as subbase or base course layers. The compound and universal models yielded the best correlation coefficients. Furthermore, the results showed that as the compaction energy increased, the resilient modulus also increased, as long as they are within the optimum water content and compaction degree limit. However, when subjected to immersion in water for four days, the resilient behavior decreased about 73% in relation to unsaturated samples.

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Evaluation of Laboratory Performance and Structural Contribution of Cold Recycled Versus Hot Mixed Intermediate and Base Course Asphalt Layers in New Hampshire

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198119844761 ◽

2019 ◽

Vol 2673 (6) ◽

pp. 467-476 ◽

Cited By ~ 1

Author(s):

Rasool Nemati ◽

Eshan V. Dave ◽

Jo E. Sias ◽

Eric S. Thibodeau ◽

Ryan K. Worsman

Keyword(s):

New Hampshire ◽

Complex Modulus ◽

Resilient Modulus ◽

Asphalt Binder ◽

Asphalt Mixtures ◽

Direct Tension ◽

Local Conditions ◽

Laboratory Performance ◽

Structural Contribution ◽

Base Course

Depending on the local conditions and structural design of the pavement, multiple asphalt concrete layers including base, intermediate, and wearing courses are used. Typically, the base and intermediate layers have larger aggregate sizes and lower total asphalt binder contents as compared with the wearing course. Recently, cold recycled (CR) asphalt mixtures have gained attention as an alternative to the typical base, and to some extent intermediate courses, because of economic and environmental advantages. Challenges with CR include the potential high variability of recycled asphalt pavement (RAP) and lack of knowledge in relation to structural contribution and long-term performance of such layers. This study investigates four different types of CR and four hot mixed plant-produced asphalt mixtures (three intermediate courses and one base course) that are typical mixtures used in New Hampshire. The laboratory performance evaluation is conducted through the resilient modulus (Mr), complex modulus (E*), semi-circular bend and direct tension cyclic fatigue (S-VECD) tests. Pavement performance prediction is carried out using the results from S-VECD approach in the FlexPAVETM software. The test results indicate that the performance of CR is highly affected by the amount of oil distillate percentage in the emulsion as well as the amount of recovered binder in the RAP. While having a relatively lower rutting resistance capability, the CR mixtures maintained an acceptable fatigue performance. As compared with CR mixtures, hot mixed intermediate and base course mixtures indicated better rutting performance while having lower resistance to cracking.

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Use of Shredded Rubber in Unbound Granular Flexible Pavement Layers

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198196154700114 ◽

1996 ◽

Vol 1547 (1) ◽

pp. 96-106 ◽

Cited By ~ 1

Author(s):

Richard H. Speir ◽

Matthew W. Witczak

Keyword(s):

Resilient Modulus ◽

Constitutive Models ◽

Friction Angle ◽

Flexible Pavement ◽

Partial Replacement ◽

Universal Model ◽

Rubber Blends ◽

State Highway ◽

Base Course ◽

Aggregate Base

The major objective of the research was to conduct a study into the feasibility of using shredded rubber as a partial replacement for aggregate within conventional base and subbase materials in a flexible pavement system. A graded aggregate base and sand subbase meeting specifications for the Maryland State Highway Administration were used. The rubber used in the study consisted of a shredded product with 60 to 70 percent retained on a 9.5-mm (⅜-in.) sieve. This size was selected because of the relatively inexpensive cost to produce it and because of its adaptability to an aggregate blend. Modified and standard Proctor, California bearing ratio (CBR), and resilient modulus tests were conducted on the base/subbase-rubber blends with up to 15 percent rubber content by weight. The aggregate base blend resulted in significant decreases in both CBR and nonlinear resilient modulus at 15 percent rubber. These significant reductions led the authors to conclude that the use of shredded rubber in a dense-graded aggregate base course is not feasible. In contrast, the sand-subbase blends resulted in insignificant changes to the CBR, friction angle, permeability, and resilient modulus at higher rubber percentages. It was concluded that the sand-rubber sub-base exhibits little change compared with the virgin sand-subbase material. As a result the use of shredded rubber may be a technically feasible alternative in the construction process. Finally, two constitutive models were used in the resilient modulus analysis: the conventional K1, K2 model and a universal model incorporating an octahedral stress term (k1, k2, k3 model). Direct comparisons revealed greatly improved predictability and accuracy with the universal model for assessing the nonlinear behaviors of both aggregate types evaluated.

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Correlation Between Resilient Modulus and Permanent Deformation During a Large Scale Model Experiment of Unbound Base Course

Lecture Notes in Civil Engineering - Proceedings of the 4th Congrès International de Géotechnique - Ouvrages -Structures ◽

10.1007/978-981-10-6713-6_37 ◽

2017 ◽

pp. 377-384 ◽

Cited By ~ 1

Author(s):

Makhaly Ba

Keyword(s):

Model Experiment ◽

Large Scale ◽

Resilient Modulus ◽

Permanent Deformation ◽

Scale Model ◽

Large Scale Model ◽

Base Course

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Resilient Properties and Fatigue Damage in Stabilized Recycled Aggregate Base Course Material

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1611-04 ◽

1998 ◽

Vol 1611 (1) ◽

pp. 28-37 ◽

Cited By ~ 7

Author(s):

Khaled Sobhan ◽

Raymond J. Krizek

Keyword(s):

Elastic Modulus ◽

Fly Ash ◽

Fatigue Damage ◽

Damage Accumulation ◽

Resilient Modulus ◽

Recycled Aggregate ◽

Fiber Reinforced ◽

Base Course Material ◽

Course Material ◽

Base Course

A stabilized fiber-reinforced base course material composed largely of recycled concrete aggregate with small amounts of portland cement and fly ash was subjected to repeated flexural loading to evaluate its resilient properties and progressive accumulation of fatigue damage. Cyclic load-deformation data were recorded continuously during the entire fatigue life until fracture to determine ( a) the magnitude and variation of cumulative plastic strain and dynamic elastic modulus as a function of the number of loading cycles, ( b) a range for the resilient modulus, and ( c) the effect of fiber inclusions on the dynamic material properties and rate of damage accumulation. The extent of fatigue damage was calculated as a fatigue damage index, which is based on the cumulative energy dissipated (absorbed) during cyclic loading. All beam specimens used in this experimental program contained (by weight) 4 percent cement, 4 percent fly ash, and 92 percent recycled aggregate; the fiber-reinforced specimens contained an additional 4 percent (by weight) hooked-end steel fibers. Results show that the resilient modulus in flexure varies between about 2.75 GPa (400,000 lbf/in2.) and 10.4 GPa (1.5 million lbf/in.2) and the degradation of the dynamic elastic modulus does not exceed 25 percent of the initial modulus. Miner’s Rule of linear summation of damage is applicable to unreinforced material but not to fiber-reinforced material. In general, a modest amount of reinforcing fibers was very effective in retarding the rate of fatigue damage accumulation in this lean cementitious composite.

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