Dissertations / Theses on the topic 'Roads Base courses'

Because there is a difference in stiffness between a bridge deck and the materials used in the approach embankment, traffic loading will cause the pavement to deform relative to the bridge deck and form a ‘bump’ at the end of the bridge. This causes drivers’ discomfort and accelerated damage to the pavement. The use of concrete approach slabs constructed so as to slope down from the bridge deck beneath the pavement has been proposed as a means of alleviating this problem. In this thesis, experimental and theoretical work have been carried out to investigate the behaviour of approach slabs under repeated loading. The work is broadly divided into six sections : 1. The development of a testing facility for the testing of model approach slabs under controlled conditions. 2. The assessment of the capability and performance of the testing facility. 3. The planning and conduct of the laboratory testing for the investigation of the deformation behaviour of pavements subjected to traffic loading. 4. The formulation of a three-dimensional finite element program using Fourier transforms for the analysis of the problem. 5. The planning and conduct of monotonic and cyclic drained triaxial tests for the investigation of residual strain behaviour. 6. The analysis of the residual strains in the model embankments and the development of a numerical method for the prediction of permanent displacements. A testing facility has been developed to provide simulated traffic loading on model pavements underlain by approach slabs. Three series of tests have been carried out to investigate the effect of the orientation of the approach slab on the deformation behaviour of the pavements. It is found that with the use of inclined slabs, the deformation in the pavement surface is more gradual than for the case where a horizontal slab is used. In other words, the bump usually formed at the end of a horizontal slab can be eliminated. A finite layer method is developed in this thesis, which provides an efficient means for investigating by the moving wheel. the cyclic stresses generated in the road embankment The effect of the approach slab orientation and the pavement stiffness on the soil response can be examined. Cyclic triaxial tests have been conducted using a fully automated GDS triaxial testing system. The aim of these tests was to investigate the soil residual strain behaviour. The cyclic stress paths have been estimated from the finite layer analyses. The triaxial test results showed that the residual axial strain after the first loading cycle increased linearly with the logarithm of the number of cycles (for the 50 loading cycles carried out for each test). This relationship was to be dependent on the stress level and the gradient of the stress path. The residual strains in the model pavements have been backfigured from two of the tests. The residual strains after the first loading cycle were found to vary non—linearly with the logarithm of the number of loading cycles. However, the non—linearity was less pronounced for the initial 50 cycles or so. A stress path method was developed to utilise the cyclic test data for the prediction of residual axial strains in the pavement layers. Based on this method, the residual strains in the pavement layers after the first loading cycle can be computed. The residual deformations are then obtained by integrating the strains obtained for all the layers. This method was applied to one of the model pavement tests and the results are found to agree reasonably well with the observed values. There are a number of improvements that can be made to this method of prediction, for instance, the incorporation of a non-linear stress-strain law to predict the first cycle deformation. Also, the measurement of the actual stresses acting in the model pavements would be useful in determining the appropriate stress paths for subsequent cyclic tests.

The aim of this research project is to develop an improved backcalculation procedure, for the determination of flexible pavement properties from the Falling Weight Deflectometer (FWD) test results. The conventional backcalculation methods estimate the pavement layer moduli assuming full adhesion exists between layers in the analysis process. The method developed in this research can predict the interface condition between the wearing and the base courses in addition to the layer moduli, which can be considered an improvement to the existing procedures. A two stage database procedure has been used to predict the above parameters and to facilitate the determination of the deflection insensitive parameters. The need for this improvement arises from the large number of debonding failures which have been reported in the literature between the wearing and base courses, and the theoretical studies which identified the significance of including the interface bonding condition in the analysis process. The validation of the improved method has been carried out firstly by comparing the backcalculated results for ninety theoretical pavements with their hypothetical values, and secondly by comparing the improved procedure results with other well known programs such as WESDEF and MODULUS. Full scale pavement testing using the FWD has been performed and the backcalculated results compared with measured values for the pavement materials. Indirect tensile tests for resilient modulus of bituminous materials were carried out on cores extracted for the pavements, whereas Dynamic Cone Penetrometer (DCP) tests were conducted for the unbound materials. The Backcalculated and the physically measured results correlated well, validating the improved procedure.

Western Australia (WA) has a road network of approximately 177,700 km, including a 17,800 km stage highway system (Main Roads Western Australia 2009). This infrastructure supports a population of only about two million, and road funds always have to be carefully considered when allocated to highway authorities or other organisations. Pavement design is a process intended to find the most economical combination of suitable materials and layer thicknesses for construction. The pavement must have a carefully-specified unbound granular base to further reduce construction costs, and must be surfaced with an approximately 30 mm asphalt surface in WA. High quality aggregates are therefore required for the base course layer of a pavement because of its proximity to the road surface. Traffic loads on the road surface result in high stress levels on the base course layer. Consequently, Hydrated Cement Treated Crushed Rock Base (HCTCRB) was developed.Current pavement analysis and design in WA is thought to be sub-standard. A number of highways and roads in WA are exhibiting extensive surface damage as a result of the increasing numbers of vehicles in use. Since pavement analysis and design in WA relies predominantly on empirical design, experience and basic experimentation, explanations for the damage occurring under present conditions are difficult to determine and assess.In most areas of the USA and Europe, pavement design and analysis has entered a new era with mechanistic design replacing empirical design. Unlike the empirical approach, a mechanistic approach seeks to explain pavement characteristics under real operational pavement conditions (loads, material properties of the pavement structure, and environments), and is based on design parameters derived from sophisticated tests which can simulate real pavement conditions in the test protocol (WSDOT 2008). The mechanistic approach to pavement design produces more relevant and useful results and these procedures, along with linear elastic analysis, were introduced into Australia by the 1987 NAASRA Guide (NAASRA 1987), of which the revised version became the AUSTROADS Guide (Austroads 2004) to the Structural Design of Road Pavements. AUSTROADS published a National Pavement Research Strategy which has been the keystone for the national co-ordination of pavement research, both within government and industry.Adaptation of the Cement Modified Crushed Rock Base concept has brought about an excellent road base material for Western Australia (WA) by the addition of a small amount of cement (1-2% by mass) to a fresh crushed rock material. The mix is stockpiled for a hydration period, and after that retreated before construction, unlike the traditional concept for cement modified/stabilised materials. This material is usually called Hydrated Cement Treated Crushed Rock Base (HCTCRB), a name established by Western Australia Mainroads (MRWA). More than 250,000 tonnes of HCTCRB has been used at a cost in excess of $10 million over the last eight years.Recently, as a result of early damage on new highways and roads in WA, MRWA and its contractors and organisations have attempted to identify the cause of this damage. HCTCRB, which is currently the best option for base course materials in WA, and Crushed Road Base (CRB), the original road base material, need to be re-examined to overcome the shortcomings in terms of analysis, design, and application. All of the factors involved in HCTCRB and CRB for today’s pavement conditions have been extrapolated far beyond the bounds of the original data, and current experience shows these require detailed re-investigation.This research aimed to study on the characteristics of CRB and HCTCRB and to determine reliable mathematical material models for the improvement in the current pavement design criteria. This study also investigated both elastic and plastic behaviour of CRB and HCTCRB. In this study, there were two relevant factors of both pavement materials which are considered in order to fulfil a lack of understanding in realistic conditions in pavements of the current pavement design. 1) The material strength which indicates the limitation and stability of pavement materials under traffic loads. This study employed the Mohr-Coulomb failure envelope to define the limitation of material implementation and also brought in the resilient modulus of materials to be the significant input parameter for multilayer finite element analysis to characterise the stress distribution in pavements. 2) The pavement failure of long term road performance relating to the design life of pavements. The permanent deformation behaviour and the shakedown concept under various stress conditions, simulated from repeated load triaxial (RLT) tests, therefore, were taken into account to investigate such long-term performance of HCTCRB and CRB and then the implementation of the findings was made to the current pavement analysis and design. Furthermore, more reliable mathematic models of base course materials for short and long term performance during their service life were established based on the laboratory test results of this study.

This research provides a comprehensive study of the static and dynamic behaviours of rock with various materials and different techniques for use in pavement applications. An improvement in dynamic behaviour of rock was associated with the glass, cement and slag presences. The stiffness of rock/rubber mixtures was found to be affected by the glass addition. Moreover, artificial intelligence approaches appeared a high ability to develop a model to predict resilient modulus of base and subbase.

This study examines the use of concrete waste by-products as a new source of road construction material in Western Australia (WA). The amount of construction waste in Western Australia increases annually, whilst natural rock aggregate is in shortage.This research focuses on whether recycled concrete, derived from various sources such as by-products from the processes of manufacturing ready-mixed concrete and waste from construction and demolition (C&D), is a viable option for use as a base and sub-base course material in road building in WA.A series of laboratory tests were conducted to determine the physical, engineering and performance properties of selected research materials to evaluate their respective potential utilisation. The results demonstrate that the concrete waste materials selected from the companies: Holcim Ltd, All Earth, Capital Demolition and C&D Recycling are suitable for use as base and sub-base layers of flexible pavement in Western Australia.

Australia produces approximately 40% of the world’s bauxite and over 30% of the world’s alumina. Each year, about 25 million tonnes of bauxite residue is produced in Australia, requiring storage and maintenance. The construction and operation of such large impoundment areas is costly. During the extraction of alumina from bauxite ore using the Bayer process, a fine residue is produced called Red Mud. In West Australia, Darling Range bauxite deposits contain high levels of quartz which result in a coarse residue fraction also being produced. This fraction has been termed Red Sand with a typical particle size in excess of 90 microns. Typically, red mud and red sand are produced in almost equal quantity. Processing of red sand can neutralise the residual caustic and lower the salt content as required. Magnetic separation is also possible to produce a high silica fraction having low iron oxide content. The sustainable use of coarse bauxite residues for road construction is an attractive option with a high potential for large volume reuse.This study focuses on whether red sand is a viable option for use as a road base, embankment fills and as seawall fills in Western Australia. Red sand comes from bauxite ore, a product of intense tropical weathering. Hence, there are various physical properties resulting from the weathering process. Thus it is necessary to fully understand the characterisation of red sand with respect to its engineering properties in the initial part of this research. To satisfy minimum requirements of road bases, a soil stabilisation technique (a Pozzolanic- Stabilised Mixture, PSM) was used. The intent of this stabilisation technique was to use Western Australia’s by-products as stabilising materials. A Pozzolanic - Stabilised Mixture consisting of Class F fly ash (a by-product from a coal power station) and activators (the byproduct from the quicklime manufacturing in terms of lime kiln dust) were employed to develop pozzolanic activity. Once the appropriate mixture of red sand, fly ash, and activators was established (based on a maximum dry density and a value of unconfined compressive strength), a set of laboratory tests were performed which included a triaxial compressive strength test, a resilient modulus test, and a permanent deformation test.Comparisons were made between the stabilised red sand and the conventional road base material in Western Australia (crushed rock added with 2% General Purpose (GP) Portland Cement named Hydrated Cemented Treated Crushed Rock Base, HCTCRB). As for the use of red sand for embankments, the representative stabilised red sand (from red sand for road bases) was used to be an alternative fill embankment material. A testing program to evaluate the important properties of stabilised red sand for embankments including permeability, compressibility and strength was undertaken. The permeability, compressibility, and strength of the representative type of red sand were examined to assess the suitability of red sand as seawall fill. The application of red sand and stabilised red sand on three structures (road bases, embankments and seawalls) is also discussed.

A pavement construction designed to cope with the different type of traffic loads; it is exposed to and at the same time it can resist the effect of the climate. A road structure consists of sub- and superstructure which is divided by a boundary known as terrace. During the construction of unbound layers (base course and sub-base course) in the superstructure, it is always ensured that the material meet the requirements for bearing capacity and the degree of compaction. These parameters are controlled by various laboratory tests and control methods. To obtain increased knowledge of the material and improve the quality of the compaction in the field, it is necessary to perform laboratory tests in order to determine material properties. A base course material 0/ 32 mm limestone from Gotland (Hejdeby) was investigated in this study. To determine properties of the material various laboratory tests such as proctor compaction test, Micro-Deval, Los Angeles, and grain distribution curve are conducted. To investigate how grain size distribution affects technical properties of the material, the 0/32 mm material was modified with two different samples; grain size distribution of 2/32 mm excluding superior material content, and 0+/32 mm with enhanced superior material content. The purpose of this study was to examine changes in material behavior during proctor compaction. Two aspects of changes in material behavior were emphasized in this study; the optimal water content and maximum dry density, as well as changes of both. As a reference for the limestone features, a traditional 0/32 mm tonalite material (granite) from Vällstaverket was used relating to proctor investigation. Material's resistance to abrasion and fragmentation was investigated by two methods: Micro-Deval and Los Angeles. The results were compared with other rock materials. Furthermore the bearing capacity of the material was verified by examination of the Young's modulus and degree of compaction, as well as properties of water content and dry density, at three trial areas on Gotland. This is performed with various methods such as static plate loading test, light weight deflectometer, density gauge/SDG200, and water/sand volume meter measurement test. By comparing results from different methods of measurement, it may indicate a relationship between these. Test area 3 consists of two smaller test areas which have different water content. The bearing capacity (Young's modulus) and the degree of compaction were measured after each roller passage. Different relationships were obtained between the amount of roller overpass, with Young's modulus of material; as well as degree of compaction. It was found in this study that limestone from Gotland (Hejdeby) maintain its position as construction material for the unbound layers of the road. The result from static plate load which indicated high E V2 values (Young's modulus) was obtained from the field, and it suggests that a fine bearing capacity can be achieved in the use of limestone.

Este trabalho apresenta um estudo comparativo da eficiência de diferentes geossintéticos no reforço de base de pavimentos de obras viárias com ensaios de arrancamento de pequeno porte. Utilizou-se geogrelhas de polipropileno, poliéster e de fibra de vidro e geotêxtil tecido de polipropileno. Um solo com 58% de argila (subleito) e um pedregulho areno-siltoso (camada de base) foram empregados. Os ensaios de arrancamento foram executados com diferentes combinações entre solos e geossintéticos. Nestes foi utilizado um novo sistema de medida direta de deslocamentos ao longo da inclusão com sensores óticos a laser. Além de analisar os resultados com curvas força de arrancamento x deslocamentos, foi possível utilizar gráficos rigidez x deformação para determinar o melhor geossintético no reforço de base de pavimentos. Como o corpo-de-prova de geossintético é de tamanho reduzido, garante-se a mobilização completa do reforço durante o ensaio de arrancamento e assim, é possível obter a deformação do mesmo. A abertura frontal da caixa de arrancamento tem influência no valor da força máxima ao arrancamento registrada no ensaio. Os resultados mostram que a interação solo-reforço é mais importante que a rigidez não-confinada do geossintético no comportamento do material em situação de confinamento no interior do maciço de solo. Observou-se que a resistência de junta, a geometria e o agulhamento da geogrelha, além da granulometria do solo, afetam a rigidez inicial do sistema. A melhor opção para os solos e geossintéticos estudados segue a seguinte ordem: (1) geogrelha de polipropileno, (2) geogrelha de poliéster, (3) geotêxtil tecido de polipropileno e (4) geogrelha de fibra de vidro.
This work presents an evaluation of various geosynthetics efficiency in reinforced base course of road pavements using small scale pullout tests. It was used polypropylene, polyester and glass fiber geogrids and polypropylene woven geotextile. A soil with 58% of clay (subgrade), and a sandy-silty gravel (base course) were used. The pullout tests were conducted with different combinations among soils and geosynthetics. In these tests, a new system of direct measurement of inclusion displacements with laser optical sensors was used. Beyond analyzing the results with curves pullout force x displacements, it was possible to use graphics rigidity x deformation in order to determinate the best geosynthetic in base course reinforcement. As the geosynthetic specimen is of small size, the complete mobilization of the reinforcement is guaranteed and, therefore, it is possible to obtain its deformation. The frontal aperture of the pullout box influences the maximum pullout resistance. The results show that the soil-reinforcement interaction is more important than the unconfined rigidity of the geosynthetic on the material behavior in confinement situation inside the soil block. The joint resistance, the geogrid geometry and its nailing, besides the soil particles size, affect the initial system rigidity. Therefore, they are important for base course reinforcement of road pavements. The results showed that the best option for the soils and geosynthetics studied are in the following order: (1) polypropylene geogrid, (2) polyester geogrid, (3) polypropylene woven geotextile and (4) glass fiber geogrid.

My work deals with monitoring communications sections, which were renovated zrecyklováním existing surface. I documented these communications and to assess their condition after the time of use. Subscribed sections I put into the database PMS.

Le manque de granulats de qualité dans certaines régions françaises tend à devenir un problème majeur pour les entreprises de travaux publics. En effet, avec une consommation annuelle de 200 millions de tonnes de granulats, la route se doit de faire face en imaginant de nouvelles solutions comme la valorisation de certains matériaux.La craie, située entre roche et sol, possède une place particulière dans le monde des travaux publics. En effet, si son usage est relativement bien maîtrisé en vue de la réalisation de remblais ou de couches de forme, il en est tout autrement des couches d'assise de chaussées.Ce type de matériau est usuellement rejeté de la conception des assises de chaussées car il ne s'insère pas dans les guides normatifs utilisés par les professionnels de la route. Les performances mécaniques et la grande sensibilité à l'eau de ce matériau ne lui permettent pas d'entrer dans les spécifications requises par les normes. Cependant, il est tout à fait envisageable que la craie trouve sa place de manière totale ou partielle en assise de chaussée.Ce matériau que l'on trouve en abondance dans certaines régions françaises pauvres en granulats "haut de gamme" (Nord-Pas de Calais, Champagne-Ardenne...), pourrait ainsi palier un certain manque, participer à la préservation de ressources naturelles et économiser frais et pollution générés par un approvisionnement lointain.Ces travaux menés en partenariat entre le Laboratoire de Génie Civil de l'Ecole Centrale de Lille et le Laboratoire Routier Eurovia de Loos ont donc pour but de proposer des pistes d'amélioration des performances mécaniques de la craie en vue de sa valorisation en assise de chaussée routière

Les géosynthétiques sont utilisés depuis les années 70 dans le renforcement des plateformes granulaires reposant sur des sols de faible portance pour des applications de routes non revêtues. La complexité des mécanismes développés et la diversité des produits de renforcement nécessitent encore d’étudier ces plateformes renforcées. Un essai au laboratoire permettant de tester des plateformes à échelle réelle a été développé. Une plateforme granulaire non revêtue reposant sur un sol de faible portance a été reproduite. Un protocole de mise en place de ce sol a été élaboré pour assurer son homogénéité et la répétabilité des essais. Une instrumentation spécifique a été développée pour collecter le maximum de mesures utiles pour l’interprétation du transfert de charge et du comportement des géogrilles utilisées. Trois types de géogrille ont été testées : une géogrille extrudée et deux géogrilles tricotées de rigidité différente. Après de nombreux essais de faisabilité, dix essais ont été effectués sous un chargement cyclique sur plaque circulaire, la plateforme testée a été placée dans un banc d’essai de 1,8 m de large, 1,9 m de long et 1,1 m de haut. Sur la base du même protocole de mise en œuvre, des essais de circulation avec un Simulateur Accélérateur de Traffic (SAT) ont été effectués. Ce simulateur a été spécifiquement conçu et construit pour cette application. Pour ces essais, la plateforme testée a été placée dans le banc d’essai allongé à 5 m. La plateforme a été soumise à deux types de sollicitations : un chargement cyclique sur plaque et un chargement de circulation. Des essais de répétabilité ont permis de vérifier le protocole mis en place. A partir des essais, plusieurs observations ont pu être faites sur le comportement des plateformes granulaires, le sol peu porteur, et sur l’efficacité du renforcement. De plus, ces essais ont permis de montrer que le chargement de circulation est beaucoup plus endommageant que le chargement sur plaque. Parallèlement à ces essais, un modèle numérique a été développé en se basant sur la méthode des différences finies avec le logiciel FLAC 3D. Cette modélisation a permis de prédire le comportement de la plateforme sous le premier chargement de plaque
Geosynthetics were used since 1970 in the base course reinforcement supported by soft subgrade in unpaved road application. The various factors and parameters influencing the dominant mechanism and its relative contribution on the platform improvement explain the need of more investigations in this topic. In this research work, large-scale laboratory test was developed to study the reinforcement contribution in the unpaved road improvement. Therefore, an unpaved platform was built of 600 mm of artificial subgrade supporting a base course layer. A detailed experimental Protocol was established regarding the soil preparation, the installation and the soils compaction procedure to reproduce the site conditions and insure the platform repeatability for each test. Three geosynthetics were tested first under a cyclic plate load test. Cyclic load was performed on the prepared platform, with a maximum load of 40 kN resulting in a maximum applied pressure of 560 kPa. The platform was subjected to 10,000 cycles with a frequency of 0.77 Hz. An advanced and complete soil instrumentation was provided in order to collect the maximum data needed for thorough analysis. Quality control tests were performed before each test to verify the soil layers homogeneity and properties. Two base course thicknesses were tested under this test condition, 350 and 220 mm. Once the developed protocol was confirmed under the circular plate load tests, further tests using the Simulator Accelerator of Traffic (SAT) were performed. Indeed, the laboratory prepared platform was placed in a larger box of 1.8 m in large, 5 m in length and 1.1 m in height. The prepared platform was subjected to two solicitations: a particular plate and traffic load. The Simulator Accelerator of Traffic was developed specially for this application. A machine that simulates the traffic load under an effective length of 2 m and a velocity of 4 km/h. The two areas were instrumented: the area under the circulation load, and the area under the plat load, located aside. In addition, a numerical model based on the differential element method using FLAC 3D was developed. The model simulated the circular plate load test with the same platform configuration under monotonic load. The results were compared to the first monotonic load applied on the rigid plate experimentally

Thesis (Ph. D.)--University of Texas at Austin, 2005.
Vita. Includes bibliographical references (215-221) Also available online via UMI (http://il.proquest.com/brand/umi.shtml) and the University of Texas Libraries websites (http://www.lib.utexas.edu/).

碩士
元智大學
工業工程與管理學系
96
The on-road courier routing operation is the most critical part of air-express companies. With good routing guidelines, couriers can serve larger areas, thus the company can save the labor cost and the vehicle routing cost. Facing the ever-increasing labor and fuel costs, finding good solutions to the on-road courier routing problems becomes imperatively important to the air-express companies. This study treats the courier routing problem in suburban areas and dense urban areas as traveling salesman problem (TSP) and multi-stop location-routing problem (MSLRP), respectively. In suburban areas, the courier routing problem is formulated such that the couriers would drive to visit each customer point (delivery or pickup) exactly once to minimize the total traveled distance. Two novel approaches: stepwise-ACO (SACO) and cheapest insertion stepwise-ACO (CISACO) are proposed. Three pickup emerging patterns are tested in the numerical experiments. The results under 1-update rule show that CISACO is superior to SACO, and both approaches are better than the cheapest insertion (CI) heuristic in terms of total traveled distance. Further experiments on n-update rules show that the 1-update rule cannot guarantee the minimum total traveled distance by the three routing approaches. However, it is rather robust that CISACO approach performs no worse than the SACO approach, which is far superior to the CI approach, regardless of the updated rules or pickup patterns. In dense urban areas, the courier routing problem is formulated in such a way that the couriers would find appropriate locations of vehicle stops, each stop covering several customer ends by a foot route, to minimize the total system costs. Two solving strategies are proposed: sequential and refined strategies. The sequential strategy is used to obtain the preliminary solutions for locating the vehicle stops, assigning the customer points to each vehicle stop, and determining the foot tours and vehicle tour. The refined strategy is to further improve the routing efficiency based on the results of the sequential strategy. The numerical experiments show that the number of vehicle stops decreases with the threshold value, regardless of the strategies used. The total vehicle routing distance also decreases with the threshold value. However, the total foot routing distance will increase with the threshold value. The refined strategy is superior to the sequential strategy in terms of total delivery costs and time, for larger threshold value. Moreover, the influences of different customer distributions on the final results are also investigated with three different instance types. The air-express companies are recommended to introduce our proposed routing algorithms to examine their on-road couriers’ operations. The minimum routing distance or cost obtained by our proposed algorithms can benchmark the couriers’ and managers’ objective experiences in the on-road courier routing operations.