Road Layers Research Articles

Improved Identification and Calculation of Horizontal Curves with Geographic Information System Road Layers

Horizontal curve data are collected or calculated by transportation agencies for different purposes because there is always a demand to generate new curve data either to improve the data quality or to extend the data coverage. There are different approaches and technologies for curve data collection. The selection of methods takes into consideration accuracy, cost, and available sources. There is, consequently, a wide interest in extracting curve information from available road network data of the geographic information system (GIS). When the cost of GIS data extraction is much lower than the cost of other approaches, it is significant to improve the accuracy of GIS curve identification and calculation. This paper analyzes errors related to existing GIS curve calculation methods and introduces a new method to identify and to calculate horizontal curves with improved accuracy. The new method uses regression analysis of road vertex direction–location profiles to calculate curve radii. A freeway segment on Interstate 80 in Nevada, including the eastbound and westbound directions, was selected to evaluate the accuracy of the new method. The evaluation compared the curve calculation results and the accurate curve information from project contract plans. The evaluation results proved the effect of the new procedure on improving the accuracy of horizontal curve identification and estimation. The new method can be implemented as a GIS tool to scan GIS road networks automatically and create horizontal curve data layers. This new method can also be used to generate curve data from GPS survey data.

Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base.

Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and mixed recycled aggregates were compared. Different specimens of unbound recycled mixtures demonstrated increased resistance properties. The formation of new cement hydrated particles was observed, and pozzolanic reactions were discovered by electronon microscopy in these novel materials. The properties of recycled concrete aggregates and mixed recycled aggregates suggest that these recycled materials can be used in unbound road layers to improve their mechanical behaviour in the long term.

Feasibility study of cement-treated 0–8 mm recycled aggregates from construction and demolition waste as road base layer

Recently, both nationally and internationally, cement-treated granular materials (CTGMs) have been widely used as road base layer. However, all the researches on CTGM with recycled aggregates (RA) are limited to the coarse fraction, with a size range of 0–40 mm. In Spain, one of the recycled materials most commonly produced in construction and demolition waste (CDW) treatment plants is a mixture with around 75% of fine recycled aggregates (hereby called FRA), with 5–8 mm nominal maximum size. This material is commonly used in pipe bedding, an application that provides little or no added-value. The intent of this paper is to study the feasibility of using CTGM made with FRA as road base layer. For this purpose, six mixtures have been produced, comprising 0–8 mm FRA and 0–40 mm coarse aggregates, made of mixed recycled aggregates and recycled concrete aggregate. The main mechanical (unconfined compressive strength and modulus of elasticity) and durability (dimensional changes) properties were studied and the effects of size and aggregates’ source were analysed. To the best of the authors’ knowledge, this is the first study on the use of the fine fraction of CDW in the production of CTGM to be used as road base layer. It suggests that it is feasible to produce CTGM with 0–8 mm RA (SC20) from CDW for that purpose. In addition, CTGM with FRA have better mechanical properties and dimensional changes than CTGM with coarse recycled aggregates (SC40).

A review of specifications for lateritic materials for low volume roads

Most laterite or lateritic soils do not comply with traditional specifications for road layers. This is a particular problem when materials are required for low volume roads. However, experience with many lateritic materials has shown that they can be successfully used with specifications that are outside traditional requirements. A review of various specifications concluded that the specifications used in Brazil are probably those based on the most pertinent and detailed research. This paper discusses the wide range of specifications suggested internationally for lateritic materials and compares the properties of a number of lateritic materials successfully used in roads in various sub-Saharan countries with the Brazilian specifications suggested for interim use in southern Africa.

Calculation of Compensation to Parcels for Land Alternation Considering the Range of Adjoining Zone to Road

The parcels of land alteration by existing manual work was very inefficient in terms of time and costs. Especially it caused many difficulty in estimating compensation since the work didn't take into account the range of adjoining zone to road. This study selected Gimje City of Jeollabuk-Do as a study site and could analyze the numbers and areas of parcels of land alteration considering the range of adjoining zone to road based on cadastral maps and wide road layers from new address system. Also this study applied a fuzzy membership function according to occupation ratio to road, and analyzed compensation by the range of adjoining zone to road using individual public land price information of the parcels for land alternation. Especially, the change aspect of public and private parcels could be investigated by the range of adjoining zone to road according to the fuzzy membership function. And this study could provide very efficient data in determining the priority of the parcels for land alternation through calculating compensation of the parcels for land alternation by Eup Myeong Dong according to the range of adjoining zone to road.

EXPERIMENTAL INSIGHTS OF USING WASTE MARBLE FINES TO MODIFY THE GEOTECHNICAL PROPERTIES OF A LATERITIC SOIL

Marble spoil waste is an environmental nuisance. The effects of adding waste marble fines (WMF) on the plasticity, strength and permeability of a lateritic clay have been investigated for its potential use as a soil modifier or stabilizer of road pavement layer materials or earth-building materials. The chemical compositions of the WMF and soil were determined using X-ray fluorescence and atomic absorption spectrometry, respectively. The specific gravity, Atterberg limits, compaction, strength and permeability characteristics of the soil were determined for varying proportions of the soil-WMF blends. The properties of the natural soil – classified as clay of low plasticity (CL) andA-7-6(7), according to unified soil classification and AASHTO classification systems, respectively – were improved after the addition of 10% WMF such that it behaves like a silt of low plasticity. Therefore, WMF is recommended as a low-cost soil modifier or stabilizer for lateritic soil and well-suited for road construction applications.

Carbonation dominates the acid intake of recycled concrete aggregate subjected to intermittent leaching

Recycled concrete aggregate (RCA) is being encouraged to use as substitute materials of the virgin aggregate for the pavement materials. RCA used in road layers is submitted to intermittent leaching. The leachant neutralizes the alkali of the RCA and the leaching intermission promotes the carbonation of the RCA’s residual mortar. Both processes introduce acid to the RCA, releasing the pH-dependent toxic constituents of the RCA to the local aquifer. In this study, the acid intake caused by the leachant renewal and leachate decantation is calculated and compared with the acid intake induced by the carbonation during the leaching intermission. It is found that carbonation dominates the acid intake of the leached RCA layer while the renewal-decantation process acts only secondary role. The use of open-graded RCA base overlain by a dense pavement is recommended to reduce the carbonation rate of the RCA and to retard the leaching pH-dependent toxic elements to the local aquifer.

Fatigue durability of asphalt-cement mixtures

Abstract This paper focuses on examinations of asphalt-cement mixtures (ACM). This is a recycled material which can be used in road pavement layers. In the article stiffness modulus tests and fatigue tests of asphalt-cement mixtures were shown. The authors decided to lead research on fatigue durability of asphalt-cement mixtures to set fatigue characteristics of these materials. So far in research or other works any adequate fatigue criterion for ACM mixtures has not been developed. As a result of the examinations a level of fatigue damage was suggested. For new fatigue damage a strain level in one million load cycle was estimated. Based on that a fatigue design criterion for asphalt-cement mixtures was estimated.

Identification of Landfill Site by Using Geospatial Technology and Multi Criteria Method- A Case Study of Kathmandu, Bhaktapur and Lalitpur District of Nepal

Landfill is a mode of municipal solid waste disposal. Thus, it is imperative to select relevant site for land filling in order to curtail environmental damage and harmful impacts on wellbeing of public. Through the decades, rummage around various places for landfill site has been going on concerning its distance from artery road, resident area and water surface in order to prevent serious health and environmental hazards. In case of Nepal, Sisdole landfill site at Okharpauwa VDC in Nuwakot is struggling to manage garbage produced by the Kathmandu valley. The valley alone mounds to 700 metric tons of garbage on a daily basis that would loosened carrying capacity of the place really soon. With the intention of uncovering suitable site for alternative to present disposal site, the Multi criteria method has been applied in GIS domain. Here, data layers of land use pattern, residential areas, urban areas, roads and water bodies of the Kathmandu, Lalitpur and Bhaktapur district were mainly considered. The buffer zones were created to those 5 layers assigning various decisive factors to determine area around them within a certain distance. Then, weightings were assigned to each criterion as per their relative importance and ratings. Furthermore, weights were integrated in GIS environment to generate suitable site. Lastly, comparative study of data layers suggested that next site for dumping refuse could be the Bhaktapur district.DOI: http://dx.doi.org/10.3126/ije.v4i1.12183International Journal of Environment Volume-4, Issue-1, Dec-Feb 2014/15, page : 121-129

Road LCA: the dedicated ECORCE tool and database

This paper presents a specific tool called “ECORCE” (French acronym for ECO-comparator applied to Road Construction and Maintenance) dedicated to the road pavement life cycle assessment. This tool aims to reduce the consumption of materials, water, and energy by means of evaluating impacts. The environmental assessment has been based on the LCA framework established by the SETAC and ISO 14040 series of standards, as well as by NFP 01010 for French products. The pavement life cycle is divided into the initial construction and maintenance operations. Several functional units can be defined in order to compare roads or road layers that have been designed to offer the same service. The system is built by selecting the processes to be considered during the impact assessment; this selection step relies on lists of main processes, such as road materials, road equipment, and material transport. The keys to building this tool were to specifically propose simple functionalities for road engineers and researchers, allow for quick case study implementation, and display a user-friendly interface. Moreover, the tool takes into account civil engineering practices and provides a set of dedicated data related to road materials, road works, and earthworks. ECORCE also allows easily changing input data (geometry, operations, materials, and transport distances); its output screens and tables offer several approaches to investigating environmental LCA results on roads. It becomes possible to compare not only the materials used in a given layer but also the pavement structures composed of several layers using various mixed materials. Lastly, the tool is able to assess initial construction and maintenance policies. Various road structures and their associated traffic conditions may be examined with ECORCE. Results obtained with the tool are detailed in the paper for a highway case study aimed at demonstrating its possible uses. These results highlight that the relative magnitude of impacts from each main process can be analyzed for road design optimization. The tool reveals that road pavement materials have more impact than other processes such as transport and non-road equipment running within the life cycle. The investigation of standard road practices can thus focus on various alternative materials and pavement structures, depending on the configurable functional units already implemented in the tool, as explained in this paper. The highway case study and accompanying sensitivity testing campaign serve to discuss the benefits of this tool.

Shrinkage cracking of cement treated demolition waste as a road base

This paper presents the shrinkage cracking characteristics of cement treated demolition waste as a road base layer, which was produced by using recycled crushed concrete and masonry aggregates from construction and demolition waste (CDW). The developed method to estimate the crack pattern was based on the structural properties of cement treated demolition waste measured in the laboratory and the average climatic conditions recorded in the Netherlands. The influences of four mixture variables (masonry content, moisture content, cement content and degree of compaction) on the crack pattern were investigated. Results show that the proposed estimation model can predict the crack pattern of cement treated demolition waste comparable to the crack spacing observed in the field. The masonry variation in CDW is a key factor to determine its shrinkage cracking characteristics.

Low-Volume Roads with Neat Sand Bases

Vast areas of Southern Africa are covered with surficial sands of Tertiary to Quaternary age. These consist of aeolian sands that are widespread in the western areas of South Africa, Namibia, Botswana, Zimbabwe, and Angola and reach as far north as the Democratic Republic of Congo, as well as coastal and alluvial sands more prevalent in the eastern areas of South Africa, Mozambique, and Tanzania. Many of these sands are extremely thick and blanket most conventional construction materials, which occur only at inaccessible depths beneath them. The sands, consisting mostly of particles within the size range of 0.06 to 2.0 mm, are normally well outside standard base course specifications for roads and are routinely rejected for use. However, experience in several countries has shown that such materials can be successfully used in the upper layers of low-volume road pavements. This finding led to an investigation into the possible specification of sand for use as base; the investigation concluded that the successfully used sands appeared to be restricted to those that were dark red, which is indicative of the presence of significant iron. It was suspected that the iron was possibly producing some form of self-cementation that increased the strength of the sand, making it successful. This paper describes the results of a follow-up investigation in which several sands, including some that were not red but appeared to be successful in road pavement layers, were investigated. Sampling and testing have shown that the aluminum content also appears to have a beneficial effect on the materials and that iron is not necessarily the main contributor to performance. A preliminary test regime and suggested material specification for the use of neat sands as base are introduced.

Effect of Tire Configuration on the Performance of a Low-Volume Road Exposed to Heavy Axle Loads

A series of response measurements was conducted at an instrumented low-volume road test site to determine the effects of different tire con-figurations of a heavy vehicle on the performance of the road structure. After the measurements were made, a true three-dimensional finite element model was developed with PLAXIS 3D 2012 software. The aim of the modeling was to find explanatory factors between the measured stress–strain relationships and confirmed permanent deformations, rutting in particular, at test site conditions. A model was created with reasonable material parameters. The model produced stress levels and road surface deflections that are comparable with the measured values. The mobilizing levels of shear strains seem to explain the notable permanent deformation at the test site despite the relatively low amount of heavy traffic. The shear strain levels can also be used as an efficient tool in evaluating the effects of other variables, such as road structural layers, construction materials, and environmental conditions, on the risk that structural deterioration of roads may occur when the intensity of loading increases.

Impacts of Spatial Extend and Site Location on Calibration of Urban Growth Models

During the last decades, cities in sub-saharan Africa have undergone rapid urban growth due to increased population growth and high economic activities. This research explores the impacts of varying modelling settings including spatial extend and its location for the city of Nairobi using a cellular automata (CA) urban growth model (UGM). Our UGM used multi-temporal satellite-based data for classification of urban land-use of 1986, 2000 and 2010, road data, slope data and exclusion layer. Monte-Carlo technique was used for model calibration and Multi Resolution Validation (MRV) technique for validation. Simulation of urban land-use was done up to the year 2030 when Kenya plans to attain Vision 2030. Three spatial grid sizes varying in extent and location were applied in the UGM calibration and validation. Thus, this research explored the impacts of varying spatial extent (grid) and location on urban growth modelling and hence can contribute to an improved sustainable planning and development. This is useful for future planning as the Nairobi grows and expands into the peri-urban areas.

New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal

In recent years, with the rapid growth of economy and sharp rise of motor vehicles in China, the pavement skid resistance in tunnel portals has become increasingly important in cold region. However, the deicing salt, snow removal with machine, and other antiskid measures adopted by highway maintenance division have many limitations. To improve the treatment effect, we proposed a new snow-melting approach employing electric heat tracing, in which heating cables are installed in the structural layer of road. Through the field experiment, laboratory experiment, and numerical investigation, structure type, heating power, and preheating time of the flexible pavement heating system in tunnel portal were systematically analyzed, and advantages of electric heat tracing technology in improving the pavement skid resistance in tunnel portal were also presented. Therefore, such new technology, which offers new snow-melting methods for tunnel portal, bridge, mountainous area, and large longitudinal slope in cold region, has promising prospect for extensive application.

Instrumentation for Monitoring Pavement Performance in Cold Regions

AbstractThe mechanistic–empirical (ME) design guide developed under the National Cooperative Highway Research Program represents a true change in the approach to engineering road structures. Changes in material properties with seasonal variations in moisture and temperature condition, which influence the mechanical response of the materials and hence the structural response of road layers, forced reliance on empirical measures to predict performance. These empirical functions will require calibration to ensure the prediction model is responsive to local conditions including adopted construction practice. The performance of pavements in cold regions clearly reveal the need to properly measure the distribution of stresses, strains, moisture, and thermal regimes, within road layers over a period of time. This paper presents the design, implementation, and use of a practical road instrumentation monitoring system capable of capturing all structural and environmental data for roadways. This proposed road insta...

Exploration Results of Applying Limestone Powder in Crushed-Stone-Sand Mixtures for Road Pavement Layers

This paper presents results of exploration related to C2 and C6 crushed-stone-and-sand ready mixtures strengthened with limestone powder used in road pavement layers. Limestone powder is an industrial waste, which in Ararat region is in big volumes. The samples were taken composed of different fractions of crushed-stone and two types of sand produced from crushed basalt and crushed gravel, and were tested. The composition of ready mixtures meets the requirements of corresponding standard on grain size. To these mixtures limestone powder was added of the percentage range 0-30% of the mixture mass. The main purposes of experimental exploration were to determine the influence of different percentages of limestone powder on compression strength of crushed-stone-and-sand ready mixtures and optimal content of powder. The change of the influence grade was studied by applying different types of sands. Three cylindrical samples were made for each percentage of limestone powder according to a standard method. Compressive strengths of samples have been determined. It was concluded, that the applying limestone powder in C2 and C6 ready mixtures contributes to the cohesion of stone grains as well as to obtaining high indicators of compaction in road pavement layers. The received results allow to arrive to a conclusion that applying limestone powder according to the optimal range distinctly increases the strength characteristics of crushed-stone-sand ready mixtures which in tur contributes the effective implementation of the compacting process. Especially the influence grade is considerable in C6 ready mixtures containing a large amount of crushed stone, as well as in mixtures using sands with smaller fineness modulus.

Influence of quality and variation of recycled masonry aggregates on failure behavior of cement treated demolition waste

Cement treatment of construction and demolition waste (CDW) is a good option as a road base layer with a higher load spreading capacity for pavements. However, the quality and variation of recycled masonry in CDW change considerably in practice and this certainly influences the mechanical properties of cement treated demolition waste. This paper presents the influence of quality and variation of recycled masonry aggregates on its failure and indirect tensile strength by carrying out experimental tests in the laboratory and employing lattice modeling to analyze the fracture process. Numerical analysis and experimental results indicate that the masonry content is an important factor to determine the mechanical properties of the mixture. The failure of cement treated demolition waste originates either in the bonding layer between aggregates and matrix or through some low-quality masonry particles along the loading direction.

High-Modulus Geocells for Sustainable Highway Infrastructure

Technological innovation in geosynthetics such as high modulus (stiff) geocells (cellular confinement systems) can help achieve a more sustainable highway infrastructure. Research, testing, field trails, and case studies demonstrate how geocells increase pavement performance on one hand, while achieving sustainable goals on the other. Recent published research and testing of high-modulus Novel Polymeric Alloy (NPA) geocell-reinforced bases are briefly reviewed in this paper. NPA geocells improved strength and rigidity of flexible pavements as indicated by: increased modulus of structural layers, reduced stresses to the lower layers and decreased surface degradation. Field trials validate that NPA geocells improve the modulus of road base layers, even while reducing the structural thickness and utilizing on-site or recycled materials for structural infill. Sustainable roads can be built with less virgin resources and a smaller environmental footprint, while extending the pavement service life and decreasing maintenance.

Experimental verification of numerical model of integral bridge

The paper presents the results of analyses of displacements for a real reinforced concrete integral bridge. The research consisted of the measurement of vertical displacement in the middle of the span and lateral displacement of the abutment. Ten load cases were considered. Two of them concerned vehicles placed motionlessly, the rest ones – braking vehicles. Moreover, the influence of initial braking velocity was analysed. The results of research were compared with numerical simulations. Two options of numerical models were considered. In the first case, cooperation between construction of span and road layers was ignored, but in the second one it was not. In the both options, the same soil conditions were assumed.Cooperation between construction and road layers was took into consideration by the increase of stiffness of span. A real heterogeneous cross section was reduced to homogeneous one. Road layers were converted to equivalent concrete layers. Neutral axis, moment of inertia and thickness were calculated for a reduced cross section and applied into model.Relations between displacements and duration were presented for load cases with braking vehicles. Displacements due to braking forces and static load were compared.