Estudio experimental de las propiedades térmicas, hidráulicas y mecánicas de rellenos geotérmicos sometidos a diferentes condiciones de operación y propuesta de alternativas

RESUMEN: La investigación tiene como eje central la caracterización de rellenos geotérmicos y el estudio de la evolución de sus propiedades con el tiempo, en condiciones normales y extremas de operación. Inicialmente se evaluó el uso de rellenos geotérmicos con alta relación agua/sólido. Se determinaron la conductividad térmica, la resistencia mecánica y la permeabilidad de cinco rellenos con diferentes cantidades de agua, cemento, arena y bentonita. Además, estas formulaciones fueron sometidas a ciclos de calor-frío, hielo-deshielo y humedad-sequedad. A continuación, se propusieron y caracterizaron rellenos geotérmicos de tipo mortero fluido, con menor contenido de agua que los anteriores, y para cuya composición se emplearon diferentes adiciones y aditivos con el objetivo de mejorar sus propiedades térmicas, mecánicas e hidráulicas. Entre las conclusiones de este estudio destaca la mayor eficiencia de los rellenos de tipo mortero desde el punto de vista del rendimiento térmico, rendimiento mecánico y durabilidad, abriendo la posibilidad de su uso en aplicaciones de mayor exigencia térmica, mecánica y medioambiental.ABSTRACT: The central axis in this research is the characterisation of geothermal grouting materials and the study of the evolution of their properties along time, under normal and extreme operating conditions. Initially, the use of grouts with high water/solid ratio was evaluated. Thermal conductivity, mechanical resistance and permeability of five grouts with different amounts of water, cement, sand and bentonite were determined. Besides, these formulations were subjected to cold-heat, freeze-thaw, and dryness-humidity cycles. Next, nine fluid mortars, with lower water content, were proposed and characterised. In these formulations, different additions and additives were used with the aim to improve its thermal, mechanical and hydraulic properties. Among the conclusions of this study, highlights the higher efficiency of the fluid mortars from the point of view of the thermal, mechanical and durability performances, offering the opportunity to be used in applications of higher thermal and environmental demands.Quisiera agradecer al Ministerio de Economía y Competitividad por la financiación recibida para la realización de esta investigación a través de los proyectos IPT-2011-0877-920000 y BIA2013- 40917-R. Así como a la Universidad de Cantabria y la Escuela de Doctorado por todas las gestiones realizadas y a los laboratorios LAGUC y LADICIM por su colaboración

Decision support model for the selection of asphalt wearing courses in highly trafficked roads

The suitable choice of the materials forming the wearing course of highly trafficked roads is a delicate task because of their direct interaction with vehicles. Furthermore, modern roads must be planned according to sustainable development goals, which is complex because some of these might be in conflict. Under this premise, this paper develops a multi-criteria decision support model based on the analytic hierarchy process and the technique for order of preference by similarity to ideal solution to facilitate the selection of wearing courses in European countries. Variables were modelled using either fuzzy logic or Monte Carlo methods, depending on their nature. The views of a panel of experts on the problem were collected and processed using the generalized reduced gradient algorithm and a distance-based aggregation approach. The results showed a clear preponderance by stone mastic asphalt over the remaining alternatives in different scenarios evaluated through sensitivity analysis. The research leading to these results was framed in the European FP7 Project DURABROADS (No. 605404).The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under Grant Agreement No. 605404

Assessment of carbon black modified binder in a sustainable asphalt concrete mixture

Carbon black has been used as a modifier in conventional binders together with a relatively low percentage of SBS polymer. In addition, an Evotherm additive has been combined by the wet way with the aim of decreasing the manufacturing temperature of the asphalt mixtures. The impact of these two has been analysed with a DSR rheometer, showing an increase in stiffness. An Asphalt Concrete mixture was then designed using the experimental binder and the warm mix additive and compared with a reference mix, using a commercial polymer modified bitumen. The final experimental mixture was manufactured 15?°C cooler than usual, showing good mechanical performance despite the low percentage of natural aggregate, which was mostly composed of reclaimed asphalt and slag. Its stiffness and fatigue resistance were also investigated. Finally, the mixture was laid in an experimental road section under real conditions as proof of concept of the technology.The authors would like to acknowledge that the research leading to these results has received funding from the European Union’s Seventh Programme for Research, Technological Development and Demonstration under Grant Agreement nº 605404

Mechanical assessment of the induction heating as a method to accelerate the drying process of cold porous asphalt mixtures

Cold mix asphalts present clear advantages such as the fact that they do not need to be heated, what results in lower energy consumptions and emissions, or the possibility to be transported long distances and manufactured on an offsite. However, their use is highly limited due to the long curing times that are needed to reach their final strength and the lower mechanical performance achieved comparing to hot mix asphalts. This paper studies induction heating as a process to accelerate the drying time of the emulsion and compares it, in terms of the mixture mechanical performance, with a more conventional method in which the cold sample is heated up in an oven. Different tests, as Cantabro, stiffness and Indirect tensile strength have been carried out. The mechanical results have shown that the induction heating could be a feasible alternative to increase the initial strength and reduce the opening time for this type of layers, although more research is necessary concerning the optimization of the mixture and the improvement of the induction device configuration.This paper was financed by the Spanish Ministry of Economy and Competitiveness with funds from the State General Budget (PGE) and the European Regional Development Fund (ERDF) through the research project SIMA+ (Ref. BIA2016‐77372‐R)

Influence of traffic delay produced during maintenance activities on the life cycle assessment of a road

This paper analyses the relevance of the traffic delay generated during the A-8 Spanish Motorway maintenance activities in order to make recommendations for inclusion within the LCA of roads. Six congestion scenarios combining the level of service of the Motorway and the alternative N-634 route have been evaluated using two software packages: KyUCP (macro-simulation) and Aimsun (micro-simulation), whose results have been transferred into emissions using MOVES. After performing the LCA considering a functional unit of a 1-km lane with an analysis period of 30 years, results show the huge importance of this stage in all the scenarios analysed

Recyclability potential of asphalt mixes containing reclaimed asphalt pavement and industrial by-products

The aim of this study was the evaluation and validation of the recyclability potential of asphalt mixturesthat incorporate high proportions of by-products (electric arc furnace slag and foundry sand) andreclaimed asphalt pavement in their composition. In a first stage, the performance of these asphalt mixeswas assessed using mechanical tests such as Marshall, water sensitivity, wheel tracking, stiffness andresistance to fatigue. Then, the samples underwent thermal aging treatment in order to be used asRAP in the manufacturing of new samples. Two rejuvenators were studied to check their effectivenessfor the purpose of achieving this aim. Finally, the mechanical performance of these new mixes was eval-uated. The results demonstrated a suitable technical performance and a good recyclability of the asphaltmixes used to replace practically all conventional aggregates. However, appropriate design and evalua-tion of the mixes is required, assessing the binder properties and the mechanical performance of theasphalt mix as well as evaluating its fatigue performance.This work was supported by the European Union’s Seventh Framework Programme for research, technological development and demonstration [grant numbers 1109806.0006]; and the FPU Programme of the Spanish Ministry of Education, Culture and Sport, Madrid [grant number FPU-14/06997]

Environmental impact assessment of induction-healed asphalt mixtures

This paper demonstrates the sustainability of induction-healed asphalt mixtures (HEALROAD) by comparing the impacts this technology causes with those generated by asphalt mixtures maintained byconventional practices such as mill and overlay. The functional unit selected is a 1 km lane with ananalysis period of 30 years, and the stages considered are production, construction, maintenance,congestion, leaching and end-of-life. Two case studies have been analysed to evaluate the influence ofdifferent traffic strategies on the environmental impact of each maintenance alternative. Results showthe benefits of using the induction technology at hot points where traffic jams occur.This work was supported by the ERA-NET Plus Infravation 2014 Call under grant agreement no. 31109806.0003 - HEALROAD. Funding partners of the Infravation 2014 Call are: Ministerie van Infrastructuur en Milieu, Rijkswaterstaat, The Netherlands, Bundesministerium für Verkehr, Bau und Stadtentwicklung, Germany, Danish Road Directorate, Denmark, Statens Vegvesen Vegdirektoratet, Norway, Trafickverket-TRV, Sweden, Vegagerdin, Iceland, Ministere de l’Ecologie du Developpement Durable et de l’ Energie, France, Centro para el Desarrollo Tecnológico Industrial, Spain, Anas S.P.S, Italy, Netivei Israel - National Transport Infrastructure Company LTD, Israel and Federal Highway Administration USDOT, USA. The HEALROAD project has been carried out by the University of Cantabria, University of Nottingham, German Federal Highways Research Institute (BASt), European Union Road Federation (ERF), Heijmans Integrale projecten B.V. and SGS INTRON B.V

Recyclability Potential of Induction-Healable Porous Asphalt Mixtures

ABSTRACT: The potential recyclability of healable asphalt mixtures has been analyzed in this paper. A healable porous asphalt mixture with steel wool fibers was artificially aged in order to assess its recyclability. This mixture was used as reclaimed asphalt in a new porous asphalt mixture, whose mechanical and healing capacities were studied and compared with the behavior of the original porous asphalt mixture. The quantity of reclaimed asphalt mixture added was 40%; besides, in order to recover the properties of the aged binder, and incorporate the last advances in the recyclability of bituminous mixtures, a rejuvenator was also added (SYLVAROADtm RP1000). The voids test, Cantabro particle loss test, water sensitivity test, stiffness test, and fatigue resistance test were performed to mechanically study the experimental mixture, while the last one (fatigue resistance test) was also used to assess its healing capacity. The results have shown that the healing capacity of the original healable porous asphalt mixture is maintained with similar mechanical performance

Asphalt mixtures with high rates of recycled aggregates and modified bitumen with rubber at reduced temperature

An asphalt concrete and a very thin asphalt concrete have been designed with more than 80% of alternative aggregates (primary slag of electric arc furnace and RAP). A modified bitumen with rubber from end-of-life tires, and a fatty acid amide wax to decrease the manufacturing temperature were used. The process of manufacturing has been carried out at the easiest way. Both mixtures were manufactured at conventional temperature without wax (170°C), and at reduced temperature when the wax was incorporated (150°C). Their mechanical and dynamic performance was compared. The resistance against plastic deformation and the effort that has to be made for the compaction of the mixtures modified with the wax at reduced temperature did not change, but the indirect tensile strength ratio decreased. The stiffness in the mixtures with wax was slightly higher, and there were not significant differences in the resistance to fatigue, although it seemed to decrease when the wax was added