Centro de Estudios de Carreteras
The activities undertaken by the Centro de Estudios de Carreteras in 2003 revolved around high-level technical assistance, applied research and technological development, all of which dealt with planning, constructing and carrying out maintenance work on the highway networks, together with traffic engineering and road safety activities.
One major part of the work was commissioned by the Directorate General of Roads (DGR) of the Ministry of Fomento, but the Centre also collaborated with other DGs of the State and Regional Administrations, and public and private companies. The Centre played a very active part in several European projects during the course of 2003.
SCRIM device for routine measurement of skid resistance in the HERMES Project test conducted in Nantes (France)
The completion of a series of accelerated full scale pavement tests for the DGR of the Ministry of Fomento was a particular important case of works and studies conducted by the LABORATORY OF ROAD INFRASTRUCTURE. The tests were performed between 1997 and 2003, with the aim of assessing the durability of different subgrades for road pavements. In particular, studies involved lime and cement stabilized soil courses with different thicknesses, placing interlayers of geotextiles, the use of soil with varying qualities, etc. The studies were conducted for two different subgrade moisture contents: first of all, under construction moisture conditions, and, secondly, after flooding the embankment soil until the water table reached a certain level. The results proved to be of particular interest in designing and devising support for road pavements, because they made it possible to classify different solutions from a durability perspective, and offer numerous aspects that amount to a novelty that will affect the treatment that has hitherto been given at the transition between earthworks and the pavement itself.
Evaluation of response models
A series of materials for wearing courses was also studied as part of this test programme: highly porous asphalt, gap graded asphalt mixes for wearing courses, cold thin layers, etc., to find out how they performed with respect to tyre-pavement adhesion and the way the surface texture evolves with traffic running on it.
Technical assistance was also given to the DGR of the Ministry of Fomento in finding design solutions, and three new activities began towards the end of the year. The first involves analysing the pavement design methods used by different European countries, comparing the way they put these methods into practise and the pavements that they use, with the situation in Spain.
The aim of the second task is to draw up a series of recommendations for road pavements of tunnels based upon Spanish and European practise, whereas the third activity will consist of preparing a manual for designing the bridge approaches. The period for conducting these studies ranges from one to two years.
A series of recommendations for the new drafting of the port pavement design document ROM 4.1-94 "Designing and Constructing Port Pavements" has been prepared for the Public Entity Puertos del Estado. In 2003, the reports for the ports of Avilés and Almería were issued, as part of the agreement "Monitoring the performance of port pavements, 2001/02 Campaign", and the groundwork was started for the next monitoring campaign. A document of recommendations was also prepared for designing and constructing concrete pavements containing metallic fibres, a material applied in port pavements. Another similar document is soon to be published concerning open graded asphalt as a carrier of cement grout.
Guidelines for pavements with cement treated layers
Two studies concerning the use of waste materials on roads were undertaken for the Directorate General of Environmental Quality and Evaluation (DGEQE) of the Ministry of Environment. The first of these involved the use of scrap tyres in bituminous materials, technical documents being prepared and regulations proposed that serve as support material for applying the technique; all of this was based upon laboratory studies and monitoring case studies where this technique has been put into practise. The second study consisted of preparing technical documents about the use of construction and demolition by-products in different road pavement layers.
Instrumentation of a pavement with deflection sensors
Work progressed on the activities carried out for different regional administrations, such as the Regional Administration of País Vasco, the aim of which is to draw up a technical standard for pavement design. As part of this agreement, pavement design bases have been established and compared with the results of the inspections that took place in preceding years. This work is expected to be completed in the first half of 2004. Work also began on the tasks involved in an agreement to advise the company GIASA (Gestión de Infraestructuras de Andalucía, S.A.), dependent upon the Regional Government of Andalucía.
One aspect of this agreement concerns updating the Technical Standard "Pavement Design for the Andalucía Road Network" (1999), and other tasks include designing and putting into operation a database containing the characteristics and performance of the sections constructed following the contents of that document, and preparing a Set of Technical Specifications to be annexed to that technical standard. A report about the specifications of organic matter content in the PG-3 article on graded aggregates was also prepared for the Regional Government of Asturias. Furthermore, instrumentation was laid, data taken and the results analysed for a recycled section, with a view to obtaining information about the way in which this type of material is affected by strain and stress caused by traffic. This work was commissioned by the Laboratori General d´Assaigs i Investigacions, which is taking part in a European project on pavement recycling.
One of the most remarkable activities carried out for other organisations involved collaborating with the Instituto Español del Cemento y sus Aplicaciones (IECA), with the help of an ad hoc committee of experts in the sector, in preparing a manual about road bases and sub-bases cement treated materials.
A variety of works were carried out for private companies, including the addition of acrylic fibre to bituminous mixes in order to make them more cohesive, for Fisipe Barcelona; a description of silicomanganese slag for Ferroatlántica; a description of zinc slag for Asúa-Erandio; the initiation of studies concerning the manufacture of a special binder for roads made of crushed granulated slag for Prefasa; the start of research work into the filler Grikol for slurry seals, the aim of which is to prevent the formation of layers of ice, for the Centro de Investigación Elpidio Sánchez Marcos; modified mix studies with Sasobit, which makes it possible to lower the manufacturing temperature, for Iberceras; research work on thermo-adhesive emulsions for Cepsa-Proas; and a description of the high stiffness mixes for Proas, or of a bituminous binder for Nynas.
3-layer pavement
The following were just some of the technical assistance activities performed in 2003: studying and developing the structure of 3-layer pavements for Probisa, defining the bearing capacity of the container yard at Fasa Renault in Valladolid, describing the mixes used for the Plasencia Cañaveral expressway for Ferrovial-Agromán, and designing a suitable pavement for withstanding the loads exerted by 120 tons tractor and trailer systems; the latter work is due to be completed in 2004, and was commissioned by Aceralia.
Measurement with sensors installed in a pavement
After the publication in 2002 of the activities involved in the first stage, the Laboratory of Road Infrastructure made further progress in 2003 with self-financed research work for the Foro de Ligantes Bituminosos (Asphalt Forum). On this occasion the work focused on studying the effects of bituminous binders on the resilient modulus, ageing and the resistance to fatigue of bituminous mixtures. This work was carried out in collaboration with numerous companies belonging to the sector (BP, CIESM, Elsan, Nynas, Proas, Probisa an Repsol-YPF). Mention must also be made here of the research work conducted into the dynamic performance of flexible pavements, which has constituted the basis for a doctoral thesis.
Finally, where European projects are concerned, reference must be made to the participation of the Centre in the SCORE project, which specialises in improving cold recycling techniques using emulsions and foamed bitumen, of great environmental interest, and of application into road maintenance and rehabilitation.
The AREA OF FULL SCALE EVALUATION has continued to collaborate with the Directorate General of Roads (DGR) in matters concerning pavement rehabilitation and providing advice for maintenance management, taking part not only in updating the pavement inventories, but also in the auscultation of the National Road Network. Where the auscultation of the road surface characteristics was concerned, work carried on with the annual skid resistance campaign that is systematically conducted on the roads in the eastern half of Spain, with a view to detecting zones with poor adhesion, so that the surface characteristics can be improved by using the required rehabilitation techniques. Work began on preparing the next auscultation campaign for 2004, for which it is also planned to take into account the ongoing measurement of the macrotexture of all the pavements, in order to complete the information provided by the measurement of the Sideway Force Coefficient.
The Centre has continued to use the Ground Penetrating Radar (GPR) equipment to measure the thickness of the layers that make up the road pavement on the National Road Network, and an initial relationship has been established between GPR data and pavement surface cracks. Furthermore, the first report on the Close Proximity Method (CPX) for measuring noise level on wearing courses was prepared. The Centre also collaborated with the Ministry of Fomento in training its personnel by giving them inspection, auscultation and pavement maintenance courses.
Crash cushions protecting a tolling area
On an international level, technical work progressed on the HERMES project, carrying out research work into friction measurement on highways, and the activities are now at the final report stage. In this sense, the Centre has taken part in reviewing all the sections, coordinating their standardisation and coherence. The Centro de Estudios de Carreteras has also participated in the European FORMAT project (Fully Optimised Road Maintenance) (2002-2005), and the SAMARIS project (Sustainable and Advanced Materials for Road Infrastructure) (2003-2005), in which the Centre is responsible for Work Package 6, concerning "Techniques for Recycling".
One of the main activities carried out for the AREA OF TRAFFIC AND ROAD SAFETY was the weigh-in-motion campaign with portable dynamic scales on the National Road Network, the 3-year campaign being completed in 2003. Information was compiled from 70 different points on the road network (including motorways, expressways, and bi-directional 2-lane roads). Weigh-in-motion scales were used because they enable the operator to automatically obtain the gross weight of each vehicle that has passed through the sites, as well as the axle loads. This equipment not only provides information about weight, but also the time at which each vehicle passes through the point, its speed, its length and its wheelbase. A visual sample of the traffic at each one of the locations was also taken at the same time, with a view to finding out other characteristics, such as the licence number (which makes it possible to deduce where the vehicle came from and its age), the type of wheels on each axle (single or double), and whether or not the trucks are running with one axle raised, or the tare and the maximum permitted weight; when this information is compared with the weight provided by the scales, this gives insight into the load of each vehicle compared to the maximum permitted load.
120 t dolly transporters (Aceralia)
The work involved in road equipment standardisation (safety barriers, signs and signals, lighting, anti-glare systems, etc.) was another field of activities carried out in the Area of Traffic and Road Safety. In this field, particular mention must be made of the preparation of technical recommendations for road restraint systems in the Region of País Vasco, which involved a study about accidents involving road restraint systems on the National Road Network highways of that Region, and a comparison of the regulations in force in different countries (United States, CEN European Standards, United Kingdom, France and Spain), and the different road restraint systems used in each of these countries.
On an international level, specifically in Europe, the Centre participated in the TREE (Transport Research for European Equipments) thematic network, which is part of the Fifth European Framework Programme for Research and Technological Development. The aim of this thematic network is to set up a transport research database in Europe -and this is already available on Internet on the website of the project (www.tree-transport-facilities.net)-, and to study the demand for using these types of facilities and the potential for establishing joint operating agreements between the different countries.
Monographic article
Foro de Ligantes Bituminosos: A different way of organising research
Foro de Ligantes Bituminosos (Asphalt Binder Forum) came into existence in 1999, when a group of research centres and companies began to carry out joint research work without any external funding. Every centre or company that participates in the Forum has to contribute to the research with the task that is allocated to them: those that have laboratories and resources to carry out the tasks incumbent upon them, do them directly, and those that do not have such means, perform their activities through contracts with other laboratories.
Taking part in the Forum are companies in the bitumen sector (BP, Nynas, Proas, Repsol), construction companies actively involved in research into products (Elsan-Pacsa, Probisa), and research centres and universities (Laboratorio de Caminos de las Escuelas Técnicas Superiores de Ingenieros de Caminos, Canales y Puertos at Barcelona and Madrid Polytechnic Universities, the Elpidio Sánchez Marcos Research Centre), and the activities are coordinated by the Centro de Estudios de Carreteras of CEDEX.
Dynamic Shear Rheometer (DSR)
Relationship between viscosity at 60ºC and the softening point (original)
The idea lying behind the group is to channel in the same direction the self-funded research work undertaken at the different research centres or companies, in such a way that this enhances its effect because a larger amount of resources are available. The research work thus performed enables those involved to coordinate their efforts and take on much more challenging tasks, thereby enabling the results to be more easily accepted by the scientific-technical community, because the findings are endorsed by numerous laboratories, the Administration and companies. The research work is clearly limited to matters of general interest in the sector, and not to the development of new products.
Another advantage in this way of working in a group is that before the research is begun, the equipment and the test methods are calibrated in such a way that results can be compared and procedural irregularities can be corrected. This would otherwise be difficult to detect with other work systems, and analysis criteria and procedures can be unified. The relationship between the working groups is also a formative and enriching experience for all those taking part, and the fact that groups of researchers are focused on one common subject greatly enhances the approaches and analyses.
The Forum has been constituted by mutual agreement among its members. It has not been set up on a permanent basis, but after the first piece of joint research work, all the participants decided to collaborate on a second one, involving other research centres.
The main aim of the first piece of research work was to analyse the relationships between the essential properties of bitumens and the performance of bituminous mixes where rutting was concerned. It is a matter of great interest, given that Europe is in a period of transition between regulations based upon empirical tests and those that use essential properties, this is, regulations that are supported by tests that enable the specialist to directly obtain the engineering properties of the materials.
Variation of deformation rate as a function of the binder nature
The aim of the exercise is to collect data and criteria, based on bituminous mixes and on the climatic and load conditions in Spain, so that these can be taken into account when drawing up the European regulations.
The conclusions that were obtained from the initial research activities constituted a major contribution to the state of the art. It was possible to observe the relationship between the empirical properties of the bitumens that are currently used and the fundamental ones that are expected to be specified in the future; information was obtained about the effects of the basic properties of bitumens in withstanding the formation of ruts, on the basis of an analysis of the performance of 14 types of bitumen; and the effects of bitumen were compared to those of other components of bituminous mixes.
Inverse of the SHRP parameter at 59ºC versus the deformation rate (original)
Furthermore, proposals for improvement were also made for the resistance to rutting test (laboratory track). The findings yielded by this research work were published in a monographic work by CEDEX and also in Spanish technical magazines, and are due to be presented in 2004 at the Euroasphalt & Eurobitumen Conference, where it has been selected as part of the limited number of papers that will be presented in a plenary session.
A second piece of research work is currently under way that carries on along the same lines as the first one. It concerns the relationship between the properties of bitumens and the modulus and the resistance to fatigue and ageing of bituminous mixes
The experimental work basically uses dynamic tests including ring tests that had never been conducted before in Spain. Very few studies of this kind have ever been undertaken on a worldwide scale with the participation of so many laboratories. It is expected that the moduli study phase will be completed by the beginning of 2005, and it is planned that the rest of the studies will be completed in 2006.