Behavior of Some Pavement Foundation Materials Under Repeated Loading

1997 ◽  
Vol 1577 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Manuel C. M. Nunes ◽  
Andrew R. Dawson
Keyword(s):  
Resilient Modulus ◽  
Bottom Ash ◽  
Triaxial Tests ◽  
Repeated Loading ◽  
Specimen Preparation ◽  
Road Pavement ◽  
Wide Range ◽  
Type Of Behavior ◽  
Resilient Behavior ◽  
Secondary Materials

A wide range of alternative materials for pavement construction were studied, and assessment techniques to enable and increase their use were developed. Five secondary materials and a conventional crushed granite were considered for use in an unbound form or lightly treated with various binders (including primary and secondary binders) in a total of 11 road pavement subbase materials. The secondary materials studied were minestone, china clay sand, slate waste, fly ash, and furnace bottom ash. The laboratory program set up for this research essentially was based on repeated-load triaxial tests, and the techniques used for specimen preparation, conditioning, and testing for resilient behavior are described. In particular, the modifications of the procedures recommended by the European Committee for Standardization necessary for testing secondary materials are identified and described. The analysis of the resilient behavior of the materials studied led to the identification of two groups with identical characteristics: unbound type of behavior (which included lightly treated mixtures), and treated type of behavior. A definition of boundaries for those groups was attempted. The mechanical properties of these materials necessary for use in analytical methods of pavement design are also presented, and the implications of treatment in terms of triaxial strength and resilient modulus are discussed.

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

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.

Direct STEM ADF imaging of gold on silicon (111)

1989 ◽  
Vol 47 ◽  
pp. 472-473
Author(s):  
P. Xu ◽  
E. J. Kirkland ◽  
J. Silcox
Keyword(s):  
Film Growth ◽  
Heavy Atom ◽  
High Vacuum ◽  
Dark Field ◽  
Thin Metal Film ◽  
Base Pressure ◽  
Ultra High Vacuum ◽  
Specimen Preparation ◽  
Dark Field Imaging ◽  
Wide Range

Many studies of thin metal film growth and the formation of metal-semiconductor contacts have been performed using a wide range of experimental methods. STEM annular dark field imaging could be an important complement since it may allow direct imaging of a single heavy atom on a thin silicon substrate. This would enable studies of the local atomic arrangements and defects in the initial stage of metal silicide formation.Preliminary experiments were performed in an ultra-high vacuum VG HB501A STEM with a base pressure of 1 × 10-10 mbar. An antechamber directly attached to the microscope for specimen preparation has a base pressure of 2×l0-10 mbar. A thin single crystal membrane was fabricated by anodic etching and subsequent reactive etching. The specimen was cleaned by the Shiraki method and had a very thin oxide layer left on the surface. 5 Å of gold was deposited on the specimen at room temperature from a tungsten filament coil monitored by a quartz crystal monitor.

Effects of fines on liquefaction behaviour in well-graded materials

2017 ◽  
Vol 54 (10) ◽  
pp. 1460-1471 ◽  
Author(s):  
Katherine A. Kwa ◽  
David W. Airey
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
State Parameter ◽  
Triaxial Tests ◽  
Particle Sizes ◽  
Graded Materials ◽  
Fines Content ◽  
Cyclic Resistance ◽  
Wide Range ◽  
Soil Behaviour

This study uses a critical state soil mechanics perspective to understand the mechanics behind the liquefaction of metallic ores during transport by ship. These metallic ores are transported at relatively low densities and have variable gradings containing a wide range of particle sizes and fines contents. The effect of the fines content on the location of the critical state line (CSL) and the cyclic liquefaction behaviour of well-graded materials was investigated by performing saturated, standard drained and undrained monotonic and compression-only cyclic triaxial tests. Samples were prepared at four different gradings containing particle sizes from 9.5 mm to 2 μm with fines (<75 μm) contents of 18%, 28%, 40%, and 60%. In the e versus log[Formula: see text] plane, where e is void ratio and [Formula: see text] is mean effective stress, the CSLs shifted upwards approximately parallel to one another as the fines content was increased. Transitional soil behaviour was observed in samples containing 28%, 40%, and 60% fines. A sample’s cyclic resistance to liquefaction depended on a combination of its density and state parameter, which were both related to the fines content. Samples with the same densities were more resistant to cyclic failure if they contained higher fines contents. The state parameter provided a useful prediction for general behavioural trends of all fines contents studied.

scholarly journals A Methodology for Determination of Resilient Modulus of Asphaltic Concrete

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
A. Patel ◽  
M. P. Kulkarni ◽  
S. D. Gumaste ◽  
P. P. Bartake ◽  
K. V. K. Rao ◽  
...  
Keyword(s):  
Resilient Modulus ◽  
Triaxial Tests ◽  
Asphaltic Concrete ◽  
Empirical Relationships ◽  
Cyclic Triaxial Tests ◽  
Electronic Circuitry ◽  
Quality Check ◽  
R Value ◽  
Vast Variation

Resilient modulus, , is an important parameter for designing pavements. However, its determination by resorting to cyclic triaxial tests is tedious and time consuming. Moreover, empirical relationships, correlating to various other material properties (namely, California Bearing Ratio, CBR; Limerock Bearing Ratio, LBR; R-value and the Soil Support Value, SSV), give vast variation in the estimated results. With this in view, an electronic circuitry, which employs bender and extender elements (i.e., piezo-ceramic elements), was developed. Details of the circuitry and the testing methodology adopted for this purpose are presented in this paper. This methodology helps in determining the resilient modulus of the material quite precisely. Further, it is believed that this methodology would be quite useful to engineers and technologists for conducting quality check of the pavements, quite rapidly and easily.

scholarly journals Resilient modulus and cumulative plastic strain of frozen silty clay under dynamic aircraft loading

2021 ◽  
Vol 3 (10) ◽  
Author(s):  
Xiaolan Liu ◽  
Xianmin Zhang ◽  
Xiaojiang Wang
Keyword(s):  
Plastic Strain ◽  
Resilient Modulus ◽  
Confining Pressure ◽  
Frozen Soil ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Research Findings ◽  
Cumulative Plastic Strain ◽  
Construction Operation ◽  
Compaction Degree

AbstractThis paper describes an investigation into the factors influencing the resilient modulus and cumulative plastic strain of frozen silty clay. A series of dynamic triaxial tests are conducted to analyze the influence of the temperature, confining pressure, frequency, and compaction degree on the resilient modulus and cumulative plastic strain of frozen silty clay samples. The results show that when the temperature is below − 5 °C, the resilient modulus decreases linearly, whereas when the temperature is above − 5 °C, the resilient modulus decreases according to a power function. The resilient modulus increases logarithmically when the frequency is less than 2 Hz and increases linearly once the frequency exceeds 2 Hz. The resilient modulus increases as the confining pressure and compaction degree increase. The cumulative plastic strain decreases as the temperature decreases and as the confining pressure, frequency, and compaction degree increase. The research findings provide valuable information for the design, construction, operation, maintenance, safety, and management of airport engineering in frozen soil regions.

scholarly journals STRUCTURAL DEVELOPMENT AND RESEARCH OF TECHNOLOGICAL PARAMETERS OF MACHINES FOR CENTRIFUGAL -PLANETARY VIBRATION TREATMENT

2020 ◽  
pp. 41-50
Author(s):  
Leonid Yaroshenko ◽  
Igor Kupchuk ◽  
Mykhailo Zamrii
Keyword(s):  
High Efficiency ◽  
Metal Removal ◽  
Three Dimensional ◽  
High Hardness ◽  
Working Environment ◽  
Repeated Loading ◽  
Structural Development ◽  
Technological Parameters ◽  
Advantages And Disadvantages ◽  
Wide Range

The paper analyzes current state and prospects of further development of technology and equipment for mechanization and automation of finishing and cleaning of details. It is stated that the most effective for this purpose are the methods of abrasive machining, which include bulk galvanizing, vibration, centrifugal-rotary and centrifugal-planetary processing. These methods reduce the complexity and cost of processing, which in some cases reaches 20% of the total cost of manufacturing parts. Each of these methods has a different level of efficiency, certain advantages and disadvantages, the level of versatility and scope of effective application. The processes of vibration processing are quite deeply studied, for its industrial mass-produced technological equipment, but they have certain shortcomings that limit their use for further widespread implementation. Centrifugal-rotary processing is a more productive process of three-dimensional finishing and cleaning treatment, but its scope is limited by the possibility of processing parts that are not complex, usually flat. The most productive methods of finishing and cleaning of details include centrifugal-planetary volume processing which high efficiency is caused by repeated loading of particles of working load by inertial forces that creates preconditions for the solutions of a wide range of technological problems, for example, processing of details of difficult form, small weight and the sizes from materials of high hardness or viscosity that represents a serious problem for other methods of volume processing. The constructive scheme is offered in the work and the influence of the composition of the abrasive free-granular working environment on the productivity of the machine for centrifugal-planetary processing of details is investigated. The kinetics of metal removal from the surface of machined parts using different types of abrasive working environment is analyzed. The results of comparative machining of parts in a torus vibrating machine and a machine for centrifugal-planetary machining are given. It is shown that the simultaneous use of centrifugal-planetary and vibration processing methods allows to increase the intensity of the process while ensuring high quality machining of parts of relatively complex shape. The constructive scheme of the machine which allows to implement the specified combined method of processing is offered and described.

scholarly journals Influence of Gradation on Resilient Modulus of High Plasticity Soil-Gravel Mixture

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Chuang Liu ◽  
Tian-Zeng Ren ◽  
Rui Zhang ◽  
Qian-Feng Gao ◽  
Jian-Long Zheng
Keyword(s):  
Resilient Modulus ◽  
Economic Benefits ◽  
Construction And Demolition Waste ◽  
Triaxial Tests ◽  
High Plasticity ◽  
Demolition Waste ◽  
Gravel Content ◽  
Coarse Aggregates ◽  
Mixing Method ◽  
Skeleton Structure

Because of low resilient modulus, high plasticity soil is often not allowed to fill road subgrades and is discarded as construction and demolition waste (CDW). To make use of the CDW, this study explored the possibility of improving high plasticity soil with gravel and examined the effect of gravel gradation on the resilient modulus of the soil-gravel mixture. A series of dynamic triaxial tests, tests of voids in coarse aggregate, and X-ray CT scans were carried out on high plasticity soil-gravel mixtures of different gravel contents and gravel gradation types. The test results show that there is a critical gravel content, that is, 44.1%. When the gravel content is less than 44.1%, the mixture shows a dense suspended structure and its modulus increases slowly with increasing gravel content. When the gravel content is greater than 44.1%, the mixture exhibits a dense skeleton structure and the modulus increases rapidly as the gravel content rises. Moreover, as the gravel gradation tends to the lower type, coarse aggregates increase in quantity and contact each other to form a dense skeleton; thus, the modulus increases accordingly. As the gravel gradation approaches the upper type, coarse aggregates decrease in quantity and tend to suspend in the soil, so the modulus decreases. With the increase in contact number, the skeleton structure is continuously improved, and thus the modulus is enhanced progressively. The results indicate that the gravel mixing method with a gravel content of 40%–45% can effectively improve high plasticity soil and shows great environmental and economic benefits.

scholarly journals Experimental Study on Dynamic Resilient Modulus of Lime-Treated Expansive Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zheng Lu ◽  
Yang Zhao ◽  
Shaohua Xian ◽  
Hailin Yao
Keyword(s):  
Moisture Content ◽  
Environmental Changes ◽  
Resilient Modulus ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
The Stability ◽  
Compaction Degree

Dynamic resilient modulus is the design index of highway subgrade design code in China, which is significantly affected by the traffic loads and environmental changes. In this study, dynamic triaxial tests were conducted to investigate the influence of moisture content, compaction degree, cyclic deviator stress, and confining pressure on lime-treated expansive soil. The suitability of UT-Austin model to lime-treated expansive soils was verified. The results indicate that the dynamic resilient modulus of lime-treated expansive soils increases nonlinearly with the increase of compaction degree, while decreases nonlinearly with the increase of dynamic stress level. The dynamic resilient modulus decreases linearly with the increase of moisture content and increases linearly with the increase of confining pressure. Moreover, the moisture content has a more significant effect on the dynamic resilient modulus of lime-treated expansive soil. Therefore, it is necessary to ensure the stability of soil humidity state and its excellent mechanical properties under long-term cyclic loading for the course of subgrade filling and service. Finally, the calculated results of the UT-Austin model for dynamic resilient modulus show a good agreement with the test results.

scholarly journals Possibilities of Use Recycled Materials in Construction Details

2019 ◽  
Vol 279 ◽  
pp. 02011
Author(s):  
Radim Smolka ◽  
Jindřich Sobotka
Keyword(s):  
Thermal Properties ◽  
Economic Costs ◽  
Recycled Materials ◽  
Roof Structure ◽  
Wide Range ◽  
Weather Resistance ◽  
User Friendly ◽  
Flat Roofs ◽  
Secondary Materials

This paper aims to explain the use of secondary materials in design details. Primarily, attention is paid to flat roofs, for which there is currently a wide range of technologies needed for user-friendly operation of a building. Recycled materials are still often looked down on and, therefore, it is important to show that even these elements may work very well in constructions. They must meet strict criteria for static and thermal properties. Furthermore, they must comply with fire and weather resistance requirements. They also have acoustic, secondary and aesthetic function. The roof structure is one of the basic segments that characterize the final properties of the building. Any malfunctions will lead to increased economic costs and degradation of users’ environment.

Analysis of Interesting Materials in the Environmental SEM: You Put What in Your Microscope?

2001 ◽  
Vol 7 (S2) ◽  
pp. 776-777
Author(s):  
John F. Mansfield
Keyword(s):  
Electron Microscope ◽  
Chemical Engineering ◽  
Materials Science ◽  
Variable Pressure ◽  
Environmental Scanning ◽  
Specimen Preparation ◽  
Wide Range ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

The environmental scanning electron microscope (ESEM™) and variable pressure electron microscope (VPSEM) have become accepted tools in the contemporary electron microscopy facility. Their flexibility and their ability to image almost any sample with little, and often no, specimen preparation has proved so attractive that each manufacturer of scanning electron microscopes now markets a low vacuum model.The University of Michigan Electron Microbeam Analysis Laboratory (EMAL) operates two variable pressure instruments, an ElectroScan E3 ESEM and a Hitachi S3200N VPSEM. The E3 ESEM was acquired in the early 1990s with funding from the Amoco Foundation and it has been used to examine an extremely wide variety of different materials. Since EMAL serves the entire university community, and offers support to neighboring institutions and local industry, the types of materials examined span a wide range. There are users from Materials Science & Engineering, Chemical Engineering, Nuclear Engineering, Electrical Engineering, Physics, Chemistry, Geology, Biology, Biophysics, Pharmacy and Pharmacology.

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