Overview on transportation infrastructure research in Portugal

Editor's Corner paperThe road infrastructures in Portugal have a great importance in the general transportation system, and the investments made in the last decades in the Portuguese road network resulted in road infrastructures of very good quality, classified by OECD (Organization for Economic Cooperation and Development) in the best places between the OECD countries. Concomitantly, the number of road accidents in Portugal deeply decreased into values only observed a few decades ago, when the traffic volume was substantially lower, which allowed to save significant amounts of the state budget. These excellent indicators obtained in Portugal are also a consequence of the advanced state of development of the Road Industry in cooperation with the main Research Centers in this field, namely the University of Minho. However, new challenges are currently posed to the transportation infrastructure Research Centers and Industry in Portugal, due to the economic crisis in the EU (European Union) and because the Portuguese road network is almost complete, needing essentially to be maintained. In fact, the pressure to get the most out of existing networks will continue to grow in Portugal, while the Portuguese companies working in this field are pursuing new opportunities to use their experience in the construction of new roads in emerging markets, namely in Eastern Europe, Northern Africa and Arabic countries, Portuguese-speaking African and American countries (Brazil, Angola and Mozambique), among others.(undefined

Fabrico de misturas betuminosas de alto módulo a menores temperaturas com betume 35/50 e parafinas

A indústria da pavimentação contribui de forma significativa para a emissão de gases causadores do efeito estufa e do desequilíbrio da atmosfera terrestre. Recentemente têmse desenvolvido um conjunto de novas tecnologias para reduzir a temperatura de produção e aplicação das misturas em obra, que ainda são mais relevantes para as misturas de alto módulo (MBAM) que são produzidas a temperaturas mais elevadas. Este estudo tem por objectivo avaliar se é possível reduzir a temperatura de fabrico e compactação das MBAM sem comprometer o seu desempenho mecânico. Para tal, produziu se uma mistura convencional AC 20 base 10/20 (MBAM) que se comparou com uma mistura equivalente modificada com parafinas AC 20 base 35/50+Sasobit® (MBAM) produzida a menores temperaturas. Este aditivo aumenta a viscosidade do betume nas temperaturas de serviço e reduz a mesma durante o fabrico (favorecendo o envolvimento dos agregados a menores temperaturas). Neste trabalho procedeu-se à formulação das misturas MBAM, à caracterização dos ligantes, à selecção da temperatura de produção da MBAM modificada e à comparação entre o desempenho das MBAM modificada e convencional, realizando ensaios de sensibilidade à água, módulo de rigidez, fadiga e deformação permanente. Foi possível concluir que a MBAM modificada tem uma sensibilidade à água e uma resistência à fadiga e à deformação permanente equivalente à MBAM convencional. Apenas se verificou uma ligeira quebra (12%) no valor do módulo de rigidez da MBAM modificada, para uma elevada redução da temperatura de fabrico e compactação (35ºC), o que permite diminuir bastante os custos energéticos, ambientais e com o betume

The importance of the use phase on the LCA of environmentally friendly solutions for asphalt road pavements

In order to assess sustainability of products and processes, different methodologies have been developed and used in the last years. In the road pavement construction area, most methodologies used for Life Cycle Assessment (LCA) are essentially focused in the construction phase. The present paper analyses the importance of the use phase of a road in the LCA of different paving alternatives, namely by evaluating energy consumption and gaseous emissions throughout the road pavement's life. Therefore, a new LCA methodology for road pavements was developed, and the results of its application to a case study involving the construction of alternative pavement structures are discussed. The study intends to assess the influence of using more sustainable paving construction alternatives (asphalt recycling vs. conventional asphalt mixtures), and/or different surface course materials (which have a higher influence on the rolling resistance and, therefore, affect the performance during the use phase). The LCA results obtained for this case study showed that the reductions in energy consumption and gaseous emissions obtained during the use phase, for pavement alternatives with a lower rolling resistance surface course, are higher than the total amount of energy consumption and gas emissions produced during construction. It is therefore clear that some improvements in the characteristics of the surface course may have an effect over the road use phase that will rapidly balance the initial costs and gas emissions of those interventions. The LCA results obtained also showed that the sustainability of pavement construction may also be improved using recycled asphalt mixtures.The authors would like to acknowledge the support given by the Portuguese Foundation for Science and Technology (FCT) to the Territory, Environment and Construction Centre, through the Project PTDC/ECM/119179/2010 and the strategic Project PEst-OE/ECI/UI4047/2014

The use of cyclic triaxial tests in the characterization of portuguese UGM

Coarse aggregate is widely used in the unbound granular layers (UGM) of roads, in particular as granular sub-base and base. However, although various studies have been conducted on these materials, their mechanical behaviour still has not been properly characterized, in Portuguese conditions, especially due to reasons connected to the heterogeneity of the rock masses from which they come from. This has special importance for Portuguese pavement technology. In the attempt of contributing for a better knowledge of that behaviour, a work was developed having the aim of obtain the mechanical characterization and the establishment of behaviour models for crushed materials coming from different lithologies, namely limestone and granite, susceptible of being used as UGM. This paper describes the principal results obtained from the work and pointing out the main directives that can be extracted from it, in terms of the global behaviour of a road pavement

Avaliação da influência da camada de desgaste na sustentabilidade dos pavimentos rodoviários

A noção de que os recursos que a humanidade tem usado não são ilimitados tem levado à implementação de práticas mais sustentáveis. Sendo os pavimentos rodoviários infraestruturas cuja construção, utilização e reabilitação provoca impactes ambientais consideráveis, torna-se indispensável a procura de novas técnicas e processos construtivos, com vista à mitigação das suas consequências. No presente artigo, para além de uma Análise do Ciclo de Vida dos pavimentos rodoviários, apresentam-se os resultados de um estudo laboratorial no qual se pretende avaliar a influência do tipo de camada de desgaste utilizada num pavimento, na variação do consumo de energia necessária à circulação.Financiado por fundos FEDER através do Programa Operacional de Competitividade - COMPETE e por fundos nacionais através da FCT - Fundação para a Ciência e a Tecnologia - no âmbito do Projeto PLASTIROADS - PTDC/ECM/119179/2010 e do Projeto Estratégico - UI 4047 - 2011-201

Asphalt mixtures produced with 100% reclaimed materials

The environmental and economic benefits of using Reclaimed Asphalt Pavement (RAP) material in hot mix asphalt (HMA) applications could be pushed up to the limit, by producing totally recycled HMAs (100% RAP), but the performance of this alternative must be satisfactory. In fact, these mixtures could possibly present a lower performance due to the behaviour of the aged binder, which loses its lighter fractions with time. In order to improve the mixture properties, a binder rejuvenator should be used. Thus, in the present study, the utilization of a used motor oil as a rejuvenator was evaluated. This would allow the modification of the aged binder, restoring some of its original properties and promoting an adequate performance of the mixture. The optimal amount of oil was determined by conventional bitumen tests, using the achievement of a bitumen with a penetration grade above, as the selection criterion for the definition of the amount of oil. Once the amount of rejuvenator (oil) was defined, laboratory specimens were prepared and tested for water sensitivity, permanent deformation, stiffness and fatigue, in order to confirm that the totally recycled mixture will perform as good as a conventional mixture used for comparison purposes.Fundação para a Ciência e a Tecnologia (FCT

Avaliação do desempenho de misturas betuminosas temperadas

A diminuição do consumo de combustíveis e das emissões de gases com efeitos de estufa são um grande desafio da sociedade actual. No fabrico de misturas betuminosas desenvolveram-se recentemente diversas tecnologias para redução da temperatura de produção e aplicação em obra que promoveram a produção de misturas betuminosas temperadas (MBT). Inúmeros benefícios no uso das MBT têm potenciado o seu crescente desenvolvimento, destacando-se a redução das emissões no fabrico e a diminuição do combustível gasto nos queimadores. Na colocação em obra, as MBT garantem uma trabalhabilidade adequada à sua aplicação e compactação a menores temperaturas, reduzindo a produção de fumos, possibilitando o transporte a longas distâncias, alargando a época de pavimentação, e permitindo a sua aplicação a temperaturas atmosféricas inferiores. Neste trabalho compara-se o desempenho mecânico de uma mistura betuminosa (AC 14 Surf 50/70) produzida a temperaturas convencionais e a menores temperaturas (125 a 135 ºC), através da introdução de dois aditivos (Sasobit® e Cecabase®). Foram determinadas as propriedades dos ligantes base e modificados (penetração, anel e bola, viscosidade e reologia) para observação do comportamento, determinação das temperaturas de fabrico e aferição da percentagem de aditivo. A caracterização das misturas foi realizada inicialmente em laboratório (propriedades volumétricas, sensibilidade à água e resistência à deformação permanente), realizando-se em seguida um trecho experimental onde foram extraídos provetes para determinação das características anteriormente referidas, além do módulo de rigidez. Em comparação com a mistura convencional, conseguiu-se reduzir a temperatura das MBT cerca de 15 a 25 ºC mantendo idênticas propriedades volumétricas e mecânicas em laboratório, o que não se conseguiu no trecho devido a um problema de contaminação com o combustível usado no queimador

Pavement recycling: an environmentally sustainable rehabilitation alternative

The preservation of environment by reducing the use of material and natural resources together with important economic savings have led pavement recycling to be a prime solution for pavement maintenance/rehabilitation. It is based on sustainable development, by reusing materials reclaimed from the pavements and reducing the disposal of asphalt materials. The present paper focuses on the analysis of a heavily trafficked urban road rehabilitation project. The original pavement design did not take into account the current traffic levels which are considerably above the initial values. The pavement was reaching failure in several areas and needed urgent measures to avoid complete failure. The pavement condition was a result of lack of structural strength and a deficient drainage. A semi-rigid pavement structure was proposed in order to improve the bearing capacity of the pavement and minimize the maintenance operations in the future. The operations involved cold “in situ” recycling of part of the existing bituminous layers and the top part of the granular layers with the addition of cement, and the overlay with new bituminous mixtures incorporating a significant percentage of materials reclaimed from the surface course of the same pavement. This solution allowed the maintenance of the pavement level (without the need for footpath reconstruction) and minimized the use of new materials, contributing towards a sustainable development

Betumes modificados com resíduos para aplicação em misturas convencionais e recicladas

O principal objetivo deste trabalho é o desenvolvimento de ligantes que maximizem a utilização de resíduos e reduzam a quantidade de betume novo a utilizar nas misturas betuminosas. Deste modo, diferentes percentagens de óleo de motor usado e polietileno de alta densidade reciclado foram adicionados a um betume convencional e, posteriormente, a 50 % de betume envelhecido. Os betumes modificados e finais foram caracterizados através do ensaio de penetração, temperatura de amolecimento e viscosidade. Concluiu-se que a mistura reciclada com 50 % de material fresado e betume modificado apresenta características mecânicas superiores à mistura convencional e não apresenta riscos a nível ambientalFinanciado por fundos FEDER através do Programa Operacional de Competitividade – COMPETE e por fundos nacionais através da FCT – Fundação para a Ciência e Tecnologia no âmbito da bolsa de doutoramento (SFRH/BD98379/2013

Innovative low noise surfaces : comparison of damping and absorption

While sound absorption is an acoustic related property reasonably well known and currently used to characterize low noise surfaces, damping is a property commonly used in other domains to define the energy dissipation of a material but rarely used to characterize this important mechanism in road pavements. This paper compares noise related properties such as damping and absorption of five road pavement surfaces. Two of which are innovative and therefore expected to be low noise since they have high voids content, incorporate fine grading aggregates and expanded clay. Other two incorporate rubber and waste high-density polyethylene giving them an elastic and stiff behaviour respectively. The fifth is a conventional material, asphalt concrete, used for control. Sound absorption tests and mechanical impedance tests were carried out in 30x30 cm slabs at 20ºC. To measure absorption, an impedance tube with an open end was put on the surfaces. To determine damping, the response of a hammer impact measured by an accelerometer on suspended slabs was analysed. Results show that the innovative surfaces have better acoustic related properties while the surface with high-density polyethylene provided the worst results. Furthermore, a strong correlation of damping and air voids was found.(undefined