Research projects

The proposed idea is to reduce the high price of traditional corrosion probes, data acquisition equipment, active personnel in charge of corrosion evaluation from the acquired data, and management of the results. This idea is research on developing a low-cost IoT (Internet of the Things) based corrosion module for estimating the corrosion of metallic elements of Spanish ports.

This system will be based on corrosion data fusion of differential Electrical Resistance (ER) and Electrochemical Impedance Spectroscopy (EIS) probes. The section metal loss across specific lengths of a metallic property can be calculated using the differential ER probes. However, differential ER probes are expensive and their connection to Arduino based technology is not available. Thus, this research proposes a low-cost ER probe based on the technology of resistance estimation of an unknown metallic component by comparing its voltage drop ends with those of a known resistor.

To improve the resolution of the low-cost ER probe, a number of estimations using various resistors with known resistances are proposed. It should also be mentioned that EIS probes can provide a range of information on the coatings of a specific point. In this research, their connectivity to an Arduino will be studied. Also, instead of using traditional commercial data acquisition systems, a Modular Unit Monitoring (MUM) system, which recently has been developed by this investigation group, will be used.

The MUM is submitted for a European patent and consists of an Arduino Due, which works as the signal conditioner of the system and a Raspberry Pi, which functions as the data acquisition equipment. So far, this system has been adapted to work with either an accelerometer, inclinometer, thermometer, analog and digital ranging sensors, humidity, and soil moisture sensors of the research group. The MUM is validated in laboratory conditions (Technology Readiness Level (TRL) of 4). Reaching TRL 3 state for the proposed corrosion module during this research is expected.

Fibre reinforced concrete (FRC) has shown to improve, by adding the appropiate quantity and type of fibres, the ductility of the material compared with the quasi-brittle behviour typical of plain concrete. The structural use of FRC has been boosted in recent years by the appearing of several national codes for structural design of concrete structures that have included recommendations for their use (fib Model Code 2010, ACI 544, and others).

Moreover, the development of a varied range of fibre types with various geometries and improved mechanical properties together with the advacne in knowledge regarding the mechanical behaviour under tensile and shear stresses, justifies the more and more applications reported using FRC. Such applications take advantage of the notiecceable structural capacities of FRC and the best performance in some other requirements (as in tunneling, wind-towers incresingnly higher, pipleines and others).

Having said that, FRC is still used for only several applications and is not widespreadly used in the most conventional structural design tasks, existing a gap between research and structural design consierations. This induces to a lack of reliability from the point of view of designers or some oversizing of the prizes. All in all, it provokes reluctance to the use of FRC.

The aim of the project SAES-HRF is an ambitious answer with the target of solving those aspects that are hindering the extension in use of FRC. Summarizing, the project attemps to respond to the following technological and scientific terms:

- To broaden and contribute to the knowledge concerning structural reliability of FRC elements. Particularly, calibrate the overall safety coefficients appropiate to be used for this material in both tensile and shear stresses.

- Propose improvemente improvements in technological aspects regarding the prodcution of FRC in order to enhance quality control and monitoring structures.

- Provide with models that represent accurately the structural response un static loadigns, shear, torsion, cyclic loadings and seismic behaviour, with special attention to fatigue and flexural situations.

- Progress in the material modelling of the long-term loading response, especially creeping and shirnkage (in craking stages)

- Provide with results about the loss of bearing capacities of FRC when subjected to high-temperture states as those that occur in fire situations in tunneling precast elements

With all these advances, the project willl supply not only technological and scientific contributions but also providing with enhancements to social progress. On the one hand, Spanish Engineering and Construction Companies may be in a privilege position for international competitive tendering. On the other hand, it will allow improving sustanaibility of such structural applications as it advances to new material and structural modelling with more optimum utilisation of the raw materials.

For that purpose, this project coordinates four consolidated reserch groups, leader in their fields in national and international terms. In order to improve the cordination, the scheme is divided into 2 sub-projects that permit addressing in an integrated way a complex and ambitious project.

The current economic context leads to rethinking the usual scenarios for investment in new infrastructures, consolidating new options for repairing and rehabilitating existing heritage. This option not only allows a better use of the public resources invested, but also contributes decisively to an improvement in the sustainability of our society, reducing the consumption of raw materials and the emission of polluting agents.

In this context, the repair and rehabilitation of transport infrastructures, such as tunnels, bridges and embankments, is of vital importance. Not only because of the needs that will arise after a few years, when many of the infrastructures built during the years of the economic boom and construction reach their service life, but also because of the social demand to make proper use of the infrastructures built. Society as a whole demands no more waste of public expenditure.

Given the high investment of resources in the construction of this heritage, investing in repair and rehabilitation operations is essential, in order to raise functionality and safety to acceptable levels once again. One of the alternatives used to structurally reinforce existing elements is the spraying of cementitious materials. Despite the great potential of the spraying technique for rehabilitation, its widespread and efficient use is limited by barriers that must be overcome. At present, there is not enough knowledge about the material, technical and structural calculation resources needed to carry out reinforcements by means of spraying in a single layer that safely meets all the requirements posed.

Therefore, the MAPMIT project aims to respond to the challenges outlined above, providing a scientific and technological leap, which will enable the development of a new range of polyfunctional materials designed for the reinforcement and monitoring of transport infrastructures. In this way, combined with new techniques for characterisation and monitoring at an early age, as well as developing considerations and structural calculation methods, new solutions can be developed for the reinforcement, repair and rehabilitation of existing transport infrastructures, increasing the overall sustainability of the infrastructures.

The MAPMIT project seeks to act on 5 fundamental pillars:

- Improvement of the materials used, of the constructive system and of the connections with the substrate towards a polyfunctional monolayer solution, which presents better mechanical properties in the short and long term, improving the sustainability of the process and increasing the useful life of the infrastructure.

- Development of new families of alkali-free accelerators, which present better strength in the short and long term, reduce the consumption of raw materials ( accelerator, cement) and improve the bond of the sprayed concrete, especially in environments with water upwelling.

- Development of calculation methods that take into account the specificities of the sprayed material and allow an optimized design of the material in terms of shear behavior, bonding with reinforcements and creep.

- Improvement of the quality control techniques used and development of non-destructive techniques based on multisensory monitoring to evaluate the behaviour of the material sprayed with and without fibres, especially at a very early age, and

- To provide multi-criteria evaluation tools that enable the evaluation of the behaviour of the materials used and to quantify in a global manner the sustainability of the strengthening, repair and rehabilitation actions and both their need and justification, as well as the repercussion on society.

New concept of sustainable and highly durable precast segments, reinforced only with non-metallic structural fibres, to be used for tunnel construction.

More specifically:

- Design and characterization of the non-metallic FRC, which allows to obtain a suitable mix for its use in precast segments for tunnels with different soil conditions, depths, etc.

- Studies of non-metallic FRC durability to guarantee service lives of 100-150 years.

- Control tests for non-metallic FRC, to establish the amount and orientation of the fibres and the establishment of safety factors.

- Development of a structural calculation method to characterise the behaviour in the different design stages.

- Improvement of the sustainability of segments manufactured with non-metallic FRC.

- Characterisation of the behaviour of non-metallic FRC against fire actions and its behaviour once the action has ceased (post fire).

Application in all works involving the construction of tunnels with segments, which are not limited only to road tunnels and railway or metro lines, but can also be built solutions for drainage, transport of water, gas, etc ..., significantly increasing the field of application of the solution developed. The results, apart from being suitable for any type of tunnel, can be extrapolated to the precasting of any other concrete structural element, so that the achievements obtained can represent a technological advance that will amplify the efficiency and development of an entire productive sector.

A main objective of the project has been defined as well as a set of sub-objectives to be achieved gradually in order to reach the first one. Likewise, the technological objectives of the project have been specifically stated. All the objectives are aligned with the "RETOS-COLABORACIÓN" call. The planning of the project has been described in work packages, its interrelation and needs, its division in tasks, the people in charge and participants in each one and the associated deliverable documents. Both Dragados and the UPC have a wide and successful experience in the development and execution of R+D+i projects, so the coherence between the definition of the objectives and the methodology to be developed to achieve them is guaranteed.

The main technological leap proposed in this project is the development of a new concept of high durability segment with non-metallic structural fibers. The use of non-metallic fibres is for the moment very unusual (there are few examples of the manufacture of segments with non-metallic fibres in the world) due to the lack of experience with this type of fibre and the lack of knowledge of the benefits it can offer in the long term. There will be important new developments in material design, structural calculation and modelling, which will contribute to greater process efficiency, reducing costs, optimising and improving the final product in structural terms, and allowing a substantial improvement in the sustainability of both the final product and the process.

Based on the fact that this is a strategic project for the company, the economic situation the country is experiencing and this specific sector, the budget of the project has been adjusted to the minimum possible, to optimize resources, without harming its proper development. The duration of the project (39 months) has been reduced to the maximum possible, thus adjusting the total budget of the project. The duration of all project tasks has been reduced to the minimum required to ensure viability. Similarly, a reputable group of UPC teachers will support the project at no extra cost to the project. With these premises we consider that the project has the means necessary for its correct execution, and that it also contributes to an efficient use of public and private economic resources. The participation in the project has been distributed according to the capacities of each partner and their degree of final contribution. The percentage distribution of the budget is 61.50% of the industrial partner, and 38.50% by Public Research Organisation (PRO).

The Phantom-Crete project proposes a new disrutive and radical concept for the development of high-performance pervious concrete. This concept is based on two entirely new concepts:

1) the design of a new concept of aggregate with controlled dissolution in cementitious materials, and

2) the design of pervious concrete mixtures based on the study of the physics of packing and wetting phenomenon of aggregates.

The first development will allow to maintain appropriate rheology and consistency of the fresh mix, providing self-compacting characteristics to the mix and allowing the obtention of pervious shotcrete. This concept will be called 'phantom aggregate", since the aggregate will initially exist in fresh concrete, to dissolve and disappear in later stages. The controlled dissolution of the aggregates in the medium generated by the hydration of cement will allow the development of a network of interconnected pores, characteristic of pervious concrete.

The second development will also permit a radical approach to the dosing process of pervious concrete, since it would allow dosing these materials considering the study of the compactness of the granular system (sand and gravel) and by controlling the content of cement paste (cement, water and additions), such that the porosity of the material, the number of aggregate-aggregate contacts and the amount of cement paste to be distributed among them is optimized. This would result in an optimization and improvement of the properties of the material.

In Spain, there are over 1200 dams, including 600 concrete dams and practically all of them have significant parts made up from concrete structural elements, which puts us in first place in Europe by number of dams and the fourth in the world after China, the U.S. and India. The current average age of our dams is approximately 50 years.

Dam safety has been and actually is a priority line of any administration or company, because of the serious consequences of the failure of a dam. This concern is not only nationally but also internationally. In this sense, it is necessary to provide knowledge about the deleterious processes taking place in the dams, its evolution, its possible effect on the integrity and security of the infrastructure, and the most appropriate methods and materials to carry out interventions. Likewise, in the current economic and social context of rationalization and efficiency in public spending, it poses a major challenge for the managers of these infrastructures. In this sense, it should be able to prioritize interventions and / or repairs under measurable criteria.

The GESHID project addresses an integrated and transversal management, maintenance and safety assessment of the built heritage regarding hydraulic infrastructure in Spain. The integrated approach is based on the performance of three pillars:

- Improved prevention and assessment of expansive phenomena in hydraulic infrastructure, considering various types of possible reactions (alkali silica reaction, sulfate attack, remaining free lime, carbonate precipitation)

- Development of materials and methods to rehabilitate waterworks large surface infrastructures by reducing execution times, costs and maximizing the sustainability and durability of the performance

- Proposal of a management methodology and comprehensive assessment of hydraulic infrastructures, that combines concrete diagnosis, damage assessment and prioritization of investments needed to repair the infrastructure

The expected results of the project will permit safe and more rational use of resources, by facilitating the preventive study of potentially expansive aggregates and its safe use. Furthermore, it will provide advanced tools to allow the diagnosis and evaluation of expansive processes in hydraulic infrastructures. Also, new materials and methods will be developed for repairing hydraulic infrastructures in a more sustainable and durable way. Finally, a new tool for the comprehensive assessment and management of such infrastructures will be developed, which will combine damage diagnosis with the prioritization of the reparation investments.

This project is directly nestled with the Society Challenges posed within the State Plan for Scientific and Technical Research and Innovation 2013-2016, specifically within the challenge "6.4.5. Challenge action on climate change and efficiency in the use of resources and raw materials", in relation to "II. Efficient use of resources and raw materials", and specifically considering (iii) security of water infrastructures, and (vii) R&D&I related to industrial processes and less polluting products, reducing the volume of emissions to air, water and soil and efficiency from the point of view of consumption of raw materials and energy products.

Self-Compacting Concretes (hereinafter referred to as SCC) have been successfully used in a variety of structural typologies. In this sense, their use has almost always been associated with elements with small thickness and great density of reinforcement (Takeuchi et al. 1994, Okamura 1997 and Nishizaki et al., 1999). For them, the difficulties associated with concreting and vibrating the piece can lead, among others, to the non-homogeneity of the material. In the precast industries, its use has spread considerably (Natio and Hoover 2005) due to advantages such as: reduction of noise pollution in the work area, elimination of concrete hollows associated with deficient vibration of the moulds, reduction of manufacturing time and minimization of the risks involved in the manipulation of tools to improve surface finishing (Ouch et al. 2003, Cadoni et al. 2004 and Liao et al., 2006).

In the precast field is where all the improvements associated with the use of SCC can be harnessed, helping to improve surface finishing and reducing the incidence of concrete-related imperfections (Liao et al., 2006). Among the prefabricated elements are the segments for tunnels built with TBM, in which case, apart from the acoustic advantages, the phase of fixing these imperfections would be practically eliminated, improving the structural behaviour and reducing cracks during installation. Likewise, the better surface finish would result in a lower consumption of grease required to slide the segments through the brush area of the TBM (Gimeno 1999) and, therefore, in an improvement in performance during the execution of the tunnel. To all of this, must be added the importance of controlling the execution of these elements in the plant and how it subsequently influences the placement of the segments and the problems associated with the imperfections that may appear during manufacture. The doctoral thesis developed in the Department of Construction Engineering of the UPC by Calavaro (2009), highlights the importance of all these aspects and proposes methods for both control and evaluation, establishing a very important precedent and a solid basis for this study.

On the other hand, there is also the possibility of using structural fibres as a substitute element for the traditional reinforcement in the form of rebars, proving to be a highly competitive option in tunnel lining segments.

The main objective is to develop a new type of two-layer rigid road pavement, executed in an industrialised form either by conventional slipform pavers or by pavers with a high pre-compaction power such as those used for cement-treated bases, which will optimise the requirements of comfort (external noise, internal noise, vibrations), safety (adherence to braking) and rolling efficiency, always under the prism of economic cost-effectiveness. This project also seeks solutions for the rehabilitation of existing pavements that are durable, environmentally friendly, quiet and comfortable, even in ultra-thin layers.

The secondary objectives are:

- To evaluate the relevant aspects to design and maintenance bi-layer pavements and to know their functional and structural capacity, as well as the time evolution of their most important features.

- To develop tools that will allow to obtain optimum pavements according to the circumstances that shape a project: service life, noise requirements, availability of aggregates...

- To develop geotextiles suitable for its interposition between the existing pavement and the concrete reinforcement, in order to increase its durability.

- Minimizing pavement noise without compromising its anti-skid properties by developing optimized texture patterns.

- To develop repairing techniques with latest-generation materials that enable the opening to traffic after the execution of the strengthening to be done as fast as possible in just a few hours.

These objectives are perfectly aligned with those of the National Plan for Scientific Research, Development and Technological Innovation 2008-2011, in which the INNPACTO Subprogramme is framed, and more specifically within the line of "Construction, territorial planning and cultural heritage", by achieving a new type of rigid pavement for the reinforcement of existing pavements.

The general objective of this project is to develop a new structural slab with optimised efficiency with fibre-reinforced concrete (FRC) and without traditional reinforcement, in order to meet established structural requirements and guarantee a high durability of the structural element, and to reduce costs in the overall construction process, increase the competitiveness of the construction solution and improve the sustainability of the process. As a solution, it pursues a finished product that will be immediately introduced into the market (structural floor slab of optimised efficiency with HRF), which will also be complemented by a methodology of design, calculation, dosage, installation and quality control to ensure the success of the solution.

During infrastructure life cycle, both during construction and during service life, the contractor or the owner can measure different physical parameters (displacements, strains, service loads, temperatures, energy consumption) in order to know if a certain project behaves in the manner envisaged at the design stage.

However, few times the data obtained are associated with a certain probability of surpassing a limit state threshold. In most cases, the engineer decides to perform (or not) repair or maintenance tasks in the infrastructure without knowing its actual state based on the information provided by visual inspections and their own intuition and experience.

This maintenance procedure causes safety and functionality problems. In addition, inefficient maintenance is associated with a higher cost for infrastructure managers due to severe repairs or excessive energy expenditure.

Despite their usefulness, decision support systems have not yet been developed operationally because of the complexity of bringing together advanced and complex scientific, mathematical and practical aspects in areas as dispersed as parameter identification, monitoring, dynamics, energy efficiency and reliability techniques.

In addition, due to the high cost of the monitoring systems, only landmark or damaged structures are traditionally instrumented.

The purpose of this project is to correct this deficiency by developing a decision support system for managing life cycle of large civil infrastructures (intelligent infrastructure such as bridges, buildings or wind turbines).

This will consist of an inverse analysis tool, in which the functional adequacy of the infrastructures associated with certain reliability index (adequacy of structural systems, adequacy of loads, adequacy of energy balance) will be identified.

The parameter identification tool will allow quantification of the partial or total functionality of the infrastructure from its static, dynamic or energetic response in non-destructive tests by a parametric mathematical methodology (observability) from low-cost sensor monitoring, linking it with BIM models, allowing benefiting and interacting with the possibilities offered by virtual infrastructure modeling applying BIM methodology.

To this end, problems associated with the interoperability of the information flows that allow the updating of the models based on the actual response must also be solved. The great advantage of this method with respect to most of the methods presented in the literature is its versatility, since it allows the updating of any physical property of the model (in this project variables related to structure, actions or energy).

To prevent accidents and failures in transport infrastructures preventive or corrective actions are required. For safety, functionality and cost reasons, preventive actions are preferable to corrective ones.

During the life cycle of infrastructures, both in construction and in service phase, the builder or the property might measure some physical parameters (displacements, rotations, forces) in order to know if a given infrastructure (tunnel, bridge, building) behaves as expected. However, the obtained data rarely substantiate the identification of the actual state of the structure or are associated with a certain probability of failure. In most cases, technicians decide to implement (or not) maintenance or repair works on infrastructures without knowing their actual state based on monitoring information (if any), visual inspections and their own intuition/experience.

This maintenance procedure causes security and functionality problems (as demonstrated by the collapse of the I-35W Bridge) with the consequent social problem involved. Furthermore, an inefficient maintenance is associated with a higher cost for the administration for severe repairs.

To facilitate decision-making during life cycle of the infrastructures support systems must be developed. Despite their usefulness, these systems have not yet been made in the literature due to the complexity of combining advanced and complex scientific, mathematical and practical aspects in areas as diverse as structural identification, monitoring, dynamic analysis, and reliability techniques. The aim of this project is to fill this gap by developing a system to help decision-making during the life cycle of major infrastructures (smart-infrastructures such as bridges, buildings and tunnels).

The integral system to help decision-making will consist of a structural identification tool, which will identify damage in structures associated with a certain reliability. This tool will enable to locate and quantify damages in infrastructures from their static or dynamic responses in non-destructive tests by a totally new methodology: the observability.

The method of structural identification by observability techniques (without reliability) has already published by members of the investigation team for the identification of bar-element structures with static excitations. In this project, this method will be developed to solve the identification from static or dynamic response of 1D or 2D-element modeled bridges, buildings and tunnels, enabling the identification and the localization of damages with a certain associated reliability index. For the first time, the observability techniques will be applied to actual infrastructures. The main advantage of this method with respect to most of the methods presented in the literature is the fact that it is based on equations with a physical meaning (parametric method) so that the results are easily interpretable.