Durability of geothermal grouting materials considering extreme loads

The concern about the massive use of the non-renewable and very limited fossil fuels together with the well-known effects of the global warming makes it more necessary the efficient use of the current forms of renewable energy generation. Because of the crucial role played by the grouting materials in the Ground Source Heat Pumps (GSHP), a proper selection of these elements should be made based on a deep knowledge of their performance. In this paper, thermal conductivity, mechanical strength and grout-pipe permeability of four different highly workable grouts have been tested before and after they were subjected to wet-dry and freeze-thaw durability treatments. Results obtained demonstrated the harmful effects of using a large amount of mixing water in grouts subjected to those extreme loads. However, the use of these type of grouts with very good workability is still possible in GSHP installations with balanced thermal designs provided that regular operational and environment conditions are considered.The authors wish to express their gratitude to the Ministry of Economy and Competitiveness which funded this study within the Spanish National Plan for Scientific and Technical Research and Innovation (INNPACTO program) through the research project IPT-2011-0877-920000. The authors are also grateful to all the organizations and companies participating in this project: Sacyr Industrial, Universidad Politécnica de Madrid and Cype

Experimental characterization and performance evaluation of geothermal grouting materials subjected to heating–cooling cycles

In recent years, the increasing rise in environmental awareness among energy consumers has led to an increasing use of renewable energies such as the geothermal energy. An important role in the efficient exploitation of the geothermal resource is played by the grouting material placed in the borehole between the pipes and the ground. Actually, the use of proper grouts is essential to provide an effective heat transfer between the ground and the heat carrier fluid in the pipes, and also to comply with the mechanical and environmental demands. However, when it comes to the construction of the GHP installations, the grout is especially required to be easy to work with (workable) and for this reason more water than required is sometimes added. In order to assess the suitability of grouting materials with significant water/solid ratios, the thermal conductivity, mechanical strength and permeability of five different grouts and grout–pipe specimens were measured for their laboratory characterization. In addition, the grouts were subjected to heating and cooling cycles to evaluate their durability with time in terms of the potential degradation of the materials and the loss of quality of the grout–pipe interface. According to the results obtained, the grouts here tested are appropriate for most of the geothermal heat pump installations, especially for those with low to medium ground thermal properties.The authors wish to express their gratitude to the Ministerio de Economía y Competitividad which funded this study within the Spanish National Plan for Scientific and Technical Research and Innovation (INNPACTO program) through the research project IPT-2011-0877-920000

Artificial reefs built by 3D printing: Systematisation in the design, material selection and fabrication

The recovery of degraded marine coasts and the improvement of natural habitats are current issues of vital importance for the development of life, both marine and terrestrial. In this sense, the immersion of artificial reefs (ARs) in the marine environment is a way to stimulate the recovery of these damaged ecosystems. But it is necessary to have a multidisciplinary approach that analyses the materials, designs and construction process of artificial reefs in order to understand their true impact on the environment. For this reason, this paper presents the manufacture of artificial reefs by 3D printing, proposing designs with a combination of prismatic and random shapes, with different external overhangs as well as inner holes. For the definition of the artificial reef designs, criteria provided by marine biologists and the results obtained from a numerical simulation with ANSYS were taken into account, with which the stability of the artificial reefs on the seabed was analysed. Three dosages of cement mortars and three dosages of geopolymer mortars were studied as impression materials. The studies included determination of the rheological properties of the mortars, to define the printability, determination of the cost of the materials used, and determination of the mechanical strength and biological receptivity in prismatic specimens that were immersed in the sea for 3 months. To evaluate the environmental impact of the materials used in the production of the mortars, a Life Cycle Assessment (LCA) was carried out. In order to choose the mortars that encompassed the best properties studied, Multi-Criteria Decision Making (MCDM) was applied and the two best mortars were used for the manufacture of the artificial reefs. Finally, the advantages and disadvantages of the 3D printing process used were analysed. The results of the studies carried out in this research show that cement mortars have better characteristics for artificial reef applications using 3D printing, and that the technique applied for the manufacture of the artificial reefs allowed the digital models to be faithfully reproduced

Life cycle assessment (LCA) and multi-criteria decision-making (MCDM) analysis to determine the performance of 3D printed cement mortars and geopolymers

A comparison between low-clinker cement and geopolymer mortars for their application in 3 D printing is discussed in this paper. The mortars are composed of materials with low environmental impact, such as cements with low clinker content, by-products of the industry and recycled aggregates. The developed mortars were both mechanically and rheologically characterized. The environmental impact was studied by LCA. To select the most suitable dosages, MCDM analysis was applied based on cost of materials, printability and LCA. Compressive strength was considered as a normalizing parameter for both the LCA and cost. The mortars showed good printability and suitable mechanical strength, being higher in the cement mortars. The LCA showed that the geopolymer mortars have a higher environmental impact due to the use of sodium hydroxide. Likewise, MCDM revealed that low-clinker cement mortars are at the top of the ranking, due to a lower environmental impact and lower cost of materials.This work has been co-financed by the European Regional Development Fund through the Interreg Atlantic Area Programme, under the project 3DPARE (EAPA_174/2016). This work reflects the authors’ opinion, so the authorities of the programme are not responsible for the use of the information here included

Complex Optimization of Heavy Duty Asphalt Pavement Types in DURABROADS Project

DURABROADS, an EU FP7 financed project launched in 2013, and led by the University of Cantabria (Spain) aims at providing a sustainable growth through the development of innovative, cost-effective and more durable pavements. The new generation of pavement is based on innovative eco-friendly nanotechnology-enhanced asphalts as well on the optimization of procedures to build and rehabilitate durable, safer and greener road infrastructure more adapted to climate change and freight corridor traffic loads. One of the objectives of this project is to identify and evaluate the existing constraints concerning currently used road materials of heavily trafficked roads (TEN-T routes) to withstand current road challenges. Due to different traffic and climate features, four European regions (Northern, Central, Western and Southern Europe) were differentiated. The climate change elements critical to various road types were identified, reviewing the pavement deterioration forms they accelerate. The traffic loads on freight corridors were evaluated considering their accelerated pavement deterioration forms. The synergistic effect of extreme climatic and mechanical loads to pavement surface was scrutinised. A comprehensive quantification methodology for extreme traffic and climatic load combinations was suggested including technical (functional), economic, environmental and social-human aspects with appropriate weighing. Then the European region-specific ?optimal? asphalt wearing course types and road rehabilitation techniques for TEN-T routes were identified. The region-specific material and procedure optimization utilizes ? in addition to the processing of a comprehensive literature survey ? the answers coming from 81 experts of 52 European institutions to targeted questionnaire. These data were used to develop a decision support model based on AHP and TOPSIS models to facilitate the selection of asphalt pavement types. The results suggested Stone Mastic Asphalt (SMA) as the most suitable alternative in different climate change scenarios evaluated by a sensitivity analysis.This paper was possible thanks to the research project DURABROADS financed by the European Commission through the Seventh Framework Programme for Research (FP7). The authors also wish to express their gratitude to the panel of experts that contributed to enrich the quality of this paper through their valuable contribution