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Modelling of the variation of granular base materials resilient modulus with material characteristics and humidity conditions

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Journal of Road Engineering 2024年第1期4卷 27-35页

作者： Jean-Pascal Bilodeau Erdrick Leandro Perez-Gonzalez Ali Saeidi Departement de Genie Civil et Genie des Eaux Universite LavalQuebecG1V 0A6Canada Departement des Sciences Appliquees Universite du Quebeca ChicoutimiChicoutimiG7H 2B1Canada

This study aims to quantify the susceptibility of granular materials used in pavements to changes in moisture content and propose a correlation model to incorporate this susceptibility into seasonal analyses.The fines content and the percentage of fractured coarse aggregates were identified as direct indicators of the resilient modulus susceptibility to changes in water content.The results showed that the percentage of fractured coarse aggregates particles(FR)has a more significant impact on the resilient modulus(Er)of crushed granular materials used in pavement construction than the combined indicator of the fines content and sample volumetrics(nf).Crushed granular materials with a higher percentage of fractured coarse aggregates are relatively insensitive to changes in the degree of saturation,but become more sensitive as the fine fraction porosity decreases.An adjusted model was proposed based on the existing formulation,but considers a complex parameter to describe and adjust the sensitivity of base granular materials to variations in moisture content with respect to fabrication charac-teristics,fines content and volumetric properties.The model shows that the variation of Er values is below10%for fully crushed granular materials.However,it reaches approximately±12%for materials with 75%of crushed coarse aggregates andþ40%and-25%for materials with FR=50%.This model could help select good ag-gregates characteristics and adjust grain-size distribution for environments where significant moisture content variations can occur in the pavement system,such as in the Province of Quebec(Canada).As it is based on pa-rameters that can be easily determined or estimated,it also represents a valuable tool for detailed design and analysis that can consider material characteristics.

关键词： resilient modulus Degree of saturation Humidity conditions Unbound granular materials Pavement base

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resilient modulus prediction of soft low-plasticity Piedmont residual soil using dynamic cone penetrometer

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第2期10卷 323-332页

作者： S.Hamed Mousavi Mohammed A.Gabr Roy H.Borden Department of Civil Construction and Environmental Engineering North Carolina State University

Dynamic cone penetrometer（DCP） has been used for decades to estimate the shear strength and stiffness properties of the subgrade soils. There are several empirical correlations in the literature to predict the resilient modulus values at only a specific stress state from DCP data, corresponding to the predefined thicknesses of pavement layers（a 50 mm asphalt wearing course, a 100 mm asphalt binder course and a200 mm aggregate base course）. In this study, field-measured DCP data were utilized to estimate the resilient modulus of low-plasticity subgrade Piedmont residual soil. Piedmont residual soils are in-place weathered soils from igneous and metamorphic rocks, as opposed to transported or compacted soils.Hence the existing empirical correlations might not be applicable for these soils. An experimental program was conducted incorporating field DCP and laboratory resilient modulus tests on "undisturbed" soil specimens. The DCP tests were carried out at various locations in four test sections to evaluate subgrade stiffness variation laterally and with depth. Laboratory resilient modulus test results were analyzed in the context of the mechanistic-empirical pavement design guide（MEPDG） recommended universal constitutive model. A new approach for predicting the resilient modulus from DCP by estimating MEPDG constitutive model coefficients（k;,k;and k;） was developed through statistical analyses. The new model is capable of not only taking into account the in situ soil condition on the basis of field measurements,but also representing the resilient modulus at any stress state which addresses a limitation with existing empirical DCP models and its applicability for a specific case. Validation of the model is demonstrated by using data that were not used for model development, as well as data reported in the literature.

关键词： Dynamic cone penetrometer(DCP) resilient modulus Mechanistic-empirical pavement design guide(MEPDG) Residual soils Subgrade soils

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Preliminary Investigation on Establishing a New resilient modulus Test Approach for Reduced Size Asphalt Mixture Samples Smaller Than 100 mm Diameter

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Journal of Traffic and Transportation Engineering 2020年第3期8卷 93-105页

作者： Ratnasamy Munaindy Francis Xavier Fauzan Jakarni Salihudin Hassim Department of Civil Engineering Universiti Putra MalaysiaSerdangSeri Kembangan 43400Malaysia

The performance evaluation of existing flexible pavements has become a priority issue for many highway maintenances engineers.To make appropriate rehabilitation and management decisions,the engineers most often rely on efficient methods for the determination of the strength of pavement layers.resilient modulus is a very important parameter to be identified and used in pavement design.The resilient moduli of asphalt mixtures are typically measured using the indirect tension test procedure in compliance with the ASTM D4123 standard that is superseded by ASTM D7369.The standard requirement is that the prepared specimens for the tests should have a minimum height of the sample over its diameter ratio of 0.4.Generally,specimens used in the tests are either a nominal 100 mm or 150 mm in diameter with a minimum thickness over diameter ratio of 0.4.However,100 mm diameter core specimens taken from site wearing courses with thicknesses ranging from 40 mm to 50 mm most often do not fulfil the minimum ratio of 0.4 after they are trimmed for testing.Since there was no any option,part of the binder courses had to be trimmed to make up for the minimum ratio requirement.This tends to result in inaccurate assessment of the resilient modulus values of the samples.As such,a new procedure was explored to test specimens smaller than 100 mm in diameter.This may minimize the material volume requirement from the field and also for the fabrication of smaller samples in the laboratory.Based on the available thickness of wearing course or overlay,the appropriate sizes were determined.For a two-layer system a 56.3 mm diameter was deemed necessary while a 37.5 mm diameter was observed to be appropriate for a three-layer system.Such an approach for resilient modulus test using miniature specimens of 56.3 mm and 37.5 mm in diameter has a great potential for practical relevance for the industry.

关键词： resilient modulus new procedure cost time and less destructive.

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A geomechanics classification for the rating of railroad subgrade performance

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Railway Engineering Science 2022年第3期30卷 323-359页

作者： Antonio Gomes Correia Ana Ramos Department of Civil Engineering ISISEUniversity of MinhoGuimara˜esPortugal

The type of subgrade of a railroad foundation is vital to the overall performance of the track structure.With the train speed and tonnage increase,as well as environmental changes,the evaluation and influence of subgrade are even more paramount in the railroad track structure performance.A geomechanics classification for subgrade is proposed coupling the stiffness(resilient modulus)and permanent deformation behaviour evaluated by means of repeated triaxial loading tests.This classification covers from fine-to coarse-grained soils,grouped by UIC and ASTM.For this achievement,we first summarize the main models for estimating resilient modulus and permanent deformation,including the evaluation of their robustness and their sensitivity to mechanical and environmental parameters.This is followed by the procedure required to arrive at the geomechanical classification and rating,as well as a discussion of the influence of environmental factors.This work is the first attempt to obtain a new geomechanical classification that can be a useful tool in the evaluation and modelling of the foundation of railway structures.

关键词： Subgrade resilient modulus Permanent deformation Geomechanical classification

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Laboratory Evaluation of Fiber-Modified Asphalt Mixtures Incorporating Steel Slag Aggregates

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Computers, Materials & Continua 2022年第3期70卷 5967-5990页

作者： Adham Mohammed Alnadish Mohamad Yusri Aman Herda Yati Binti Katman Mohd Rasdan Ibrahim Department of Civil Engineering and Built Environment Universiti Tun Hussein Onn MalaysiaParit Raja86400Malaysia Department of Civil Engineering Universiti Tenaga NasionalKajang43000Malaysia Department of Civil Engineering Universiti MalayaKuala Lumpur50603Malaysia

Vigorous and continued efforts by researchers and engineers have contributed towards maintaining environmental sustainability through the utilization of waste materials in civil engineering applications as an alternative to natural sources.In this study,granite aggregates in asphaltic mixes were replaced by electric arc furnace(EAF)steel slag aggregates with different proportions to identify the best combination in terms of superior performance.Asphalt mixtures showing the best performance were further reinforced with polyvinyl alcohol(PVA),acrylic,and polyester fibers at the dosages of 0.05%,0.15%,and 0.3%by weight of the aggregates.The performance tests of this study were resilient modulus,moisture susceptibility,and indirect tensile fatigue cracking test.The findings of this study revealed that the asphalt mixtures containing coarse steel slag aggregate exhibited the best performance in comparison with the other substitutions.Moreover,the reinforced asphalt mixtures with synthetic fibers at the content of 0.05%exhibited an almost comparable performance to the unreinforced asphalt mixtures.Modifying the asphalt mixtures with PVA,acrylic,and polyester fibers at the proportion of 0.15%have improved the fatigue cracking resistance by 41.13%,29.87%,and 18.97%,respectively.Also,the fiber-modified asphalt mixtures with PVA,acrylic,and polyester have enhanced the fatigue cracking resistance by about 57%,44%,and 39%,respectively.The results of the resilient modulus demonstrated that as the fiber content increase,the resilient modulus of the reinforced asphalt mixtures decreases.Therefore,introducing synthetic fibers at the content of 0.3%has slightly decreased the resilient modulus in comparison with unreinforced mixtures.On the other hand,the results of the mechanisticempirical pavement design showed that the reinforced asphalt mixes with a high content of synthetic fibers have shown lower service life than the control mixes due to the low resilient modulus.On the contrary,based on the laboratory results,the asphalt m

关键词： Steel slag aggregate polyvinyl alcohol fiber acrylic fiber polyester fiber cracking resistance resilient modulus

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Rutting prediction models for flexible pavement structures: A review of historical and recent developments

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Journal of Traffic and Transportation Engineering(English Edition) 2021年第3期8卷 315-338页

作者： Auinash Kumar Singh Jagdish Prasad Sahoo Department of Civil Engineering Indian Institute of Technology RoorkeeRoorkee 247667India Department of Civil Engineering Indian Institute of Technology KanpurKanpur 208016India

Rutting is the major distress mode in flexible pavements occurring due to the repeated movement of traffic loading. Deformation in the pavements comprise of both recoverable(elastic) and irrecoverable(plastic) part. Overall deformation occurring in the flexible pavement system due to continuous vehicular movement is contributed from all the components of pavement. A number of empirical models have been proposed by several researchers for analysis and prediction of accumulated rutting in different components of pavement. The accumulated permanent strain has been expressed as the function of the number of load applications and deviator stress applications in most of the models proposed;however, factors such as stress state, moisture content, material type and environmental conditions also impose a significant influence on the permanent deformation characteristics of pavement materials under cyclic loading. In this article, a comprehensive review has been carried out covering every aspect of deformation related to distress occurring in pavements. Important rut models, modeling approaches and modern concepts in the rutting analysis of pavement structures have been presented. In addition to review, fallacy existing in the current design practices related to adaptation of stiffness parameters and negligence of shear strength aspect of subgrade soil has been also presented with the support of literatures.

关键词： Road engineering Permanent deformation Rutting models resilient modulus Shear strength

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NONLINEAR VISCOSITY OF SUBGRADE SOILS UNDER CYCLIC LOADING

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岩石力学与工程学报 2001年第6期20卷 875-881页

作者： Li Jiang (Department of’Civil Engineering, Morgan State University USA) (LRSM Institute of Rock and Soil Mechanics, The Chinese Academy of Sciences, Wuhan 430071 China) Morgan State University 美国

Experimental investigations of nonlinear shear viscosity of subgrade soils under periodic loading are conducted. Unsaturated subgrade soil samples are prepared to conduct triaxial shear tests under repeated loading that is used to simulate the cyclic stress induced by vehicles. Investigations included three aspects. First, a new nonlinear viscous model is introduced to describe the relation of shear stress and shear strain rate. This relation was reduced from the constitutive law of nonlinear poroviscosity suggested by the author before. Second, related constitutive parameters are investigated and calibrated with experimental results from triaxial shear tests. The nonlinear viscous parameters are assumed to be a function of deviatoric strain and loading repetitions. Third, both viscous and elastic behavior of soils associated with the deviatoric strain and the cyclic loading repetition is tudied. The correlation between shear viscosity and resilient modulus is discussed as well. This is the first attempt to find any correlation between soil viscosity and elasticity through laboratory investigations. In contrast, in traditional numerical computations (e.g.. the finite element method), the extra viscous term added to the governing equation is assumed to be related to system mass and rigidity.

关键词： shear viscosity deviatoric stress deviatoric strain nonlinearity resilient modulus stress invariant strain invariant strain rate constitutive relationship poroviscosity

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Impact of Freeze-Thaw Cycles on Compressive Characteristics of Asphalt Mixture in Cold Regions

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Journal of Wuhan University of Technology(Materials Science) 2015年第4期30卷 703-709页

作者：司伟 LI Ning 马骉 REN Junping WANG Hainian HU Jian Key Laboratory for Special Area Highway Engineering of Ministry of Education Chang'an University The Second Highway Engineering of China Communications Construction Company Ltd.

Low average temperature, large temperature difference and continual freeze-thaw （F-T） cycles have significant impacts on mechanical property of asphalt pavement. F-T cycles test was applied to illustrate the mixtures＇ compressive characteristics. Exponential model was applied to analyze the variation of compressive characteristics with F-T cycles; Loss ratio model and Logistic model were used to present the deterioration trend with the increase of F-T cycles. ANOVA was applied to show the significant impact of F-T cycles and asphalt- aggregate ratio. The experiment results show that the compressive strength and resilient modulus decline with increasing F-T cycles; the degradation is sharp during the initial F-T cycles, after 8 F-T cycles it turns to gentle. ANOVA results show that F-T cycles, and asphalt-aggregate ratio have significant influence on the compressive characteristics. Exponential model, Loss ratio model and Logistic model are significantly fitting the test data from statistics view. These models well reflect the compressive characteristics of asphalt mixture degradation trend with increasing F-T cycles.

关键词： freeze-thaw cycles test compressive strength resilient modulus regression models

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Characterization of subgrade soil mixed with recycled asphalt pavement

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Journal of Traffic and Transportation Engineering(English Edition) 2018年第3期5卷 207-214页

作者： Md Mehedi Hasan Md Rashadul Islam Rafiqul A.Tarefder Department of Civil Engineering University of New Mexico Civil Engineering Technology Colorado State University-Pueblo

Due to awareness to greener environment, use of recycled asphalt material has become popular in asphalt pavement industry. The use of recycled asphalt pavement （RAP） ma- terials in subgrade soil can be an additional scope of utilizing RAP. This study investigates the effect of RAP on the resilient modulus （MR） of subgrade soils mixed with RAP materials. Note that MR is the principal material input parameter for designing asphalt pavement using the recent mechanistic-empirical pavement design software. As a first step of the current study, different percentages of RAP and moisture were thoroughly mixed with subgrade soils. Then, the MR of these RAP mixed soils were determined using the AASHTO T 307 （1999） at different stress levels in the laboratory. Results show that the MR of RAP mixed soil increases with the applied deviatoric and bulk stresses, however, it is less sensitive to applied confining pressure. Use of RAP materials has made the soils stiff enough not to respond to the confining pressure. As expected, the MR value reaches a maximum at the optimum moisture content and increases linearly with RAP content. The MR values and characteristics of the RAP mixed subgrade soils, as determined by the current study, can be used for subgrade design and stabilization using RAP for better pavement design.

关键词： Subgrade Recycled asphalt pavement Moisture resilient modulus Stress

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Assessing the resilient Behavior of Recycled Mix-granulate with Repeated Load CBR Testing

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武汉理工大学学报 2010年第17期32卷 89-93页

作者： ARAY A A A MOLENAAR A A A HOUBEN L J M Road and Railway Engineering Section Delft University of Technology

A new characterization technique,a repeated load CBR test,was used to evaluate the resilient properties recycled mix-granulate unbound base material. This is a mixture of crushed concrete and crushed masonry,so recycled demolition waste,this is used on a wide scale in the Netherlands as road base material. The repeated load CBR test,done with standard CBR testing facility,was conducted to estimate the resilient modulus. For comparison and assessment purposes the tests were carried out with the same material conditions (composition,grading,moisture and compaction degree) as have been applied in earlier triaxial testing in the Road and Railway Engineering Laboratory,Delft University of Technology. The results indicate that the repeated load CBR test yields a good estimate of the stress dependent equivalent modulus for the sample material as bulk,which can be used in mechanistic pavement analysis in the absence of triaxial test results.

关键词： repeated load CBR triaxial resilient modulus recycled mix-granulate

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