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Understanding Transport for Concrete which is Eco friendly iNnovative and Durable

Final Report Summary - TRANSCEND (Understanding Transport for Concrete which is Eco friendly iNnovative and Durable)

Publishable Summary

Water transport is at the heart of degradation of concrete infrastructures, costing millions in maintenance and repair. Because concrete infrastructures are everywhere, from houses and buildings to roads, from bridges to tunnels, the understanding of water transport is crucial. Cement, the binding element in concrete is widely available and cheap; it is no surprise that cement is the most used building materials on Earth. But cement production is currently responsible for 5%-8% of global man-made CO2, emissions originating during the chemical process that transforms limestone into lime. Reducing the CO2 emissions can only come from materials with different chemistries.



The Marie Curie Initial Training Network TRANSCEND “Understanding TRANSport for Concrete which is Eco friendly iNovative and Durable” aims to develop the understanding of water transport from the nano- to macro-scale with the objective to design new more durable and sustainable cements.
To reach these objectives TRANSCEND trained fifteen Early Stage Researchers (ESRs), ultimately leading to fourteen PhDs/Engineering doctorates, and one Experienced Researcher (ER) in cement science. This four-year project was divided into three research themes: (A) five projects in theory and modeling, (B) six experimental projects and (C) four projects based in industry for verification. The network integrated thirteen full and ten associated partners: twelve Universities, four research institutes and seven industrial partners, closely integrating the academic and private sectors. The later directly employed four of the fifteen fellows. TRANSCEND started 1st of October 2010.
Four ESRs on the modeling side worked in parallel developing Molecular dynamics, Monte Carlo and Lattice Boltzman codes ranging from the nanoscale to microscale level to calculate typical characteristics of concrete. Concrete in real life is exposed to sun and rain; it may be immerged in water or standing in a desert. To study water transport, various temperatures and relative humidities must be considered as it affects concrete at different length scales ranging from nanometers to micrometers. One ESR developed numerical models of water wetting and drying fronts in cement pastes. A group of four ESRs on the experimental side worked in parallel on characterizing water in cement at different length scales. Another group focused on characterizing porosity and cracks and measured data at various temperatures and relative humidities. ESRs in industrial placements measured water transport in various settings and at different length scales.
A network of fully interlinked projects emerged with substantial interaction between partners. The hub of much of this activity was progress with Nuclear Magnetic Resonance (NMR) methods. Starting at the nanoscale, NMR projects 7 and 9 made substantive progress in characterizing the nano-morphology of cement pastes. It was shown that NMR was able to make routine measurements of calcium-silicate-hydrate (the glue of cement) composition, water content and density in never dried materials. New insights concerning calcium-silicate-hydrates in non-equilibrium conditions were fed by project 8 (Morphology of C-S-H). Using NMR, the pore-size specific sorption isotherm was measured for the first time. Projects 5 and 6 that measure and model the isotherm by more conventional methods made considerable headway in understanding the experimentally observed hysteresis. NMR know-how was passed to industrially based projects 12, 13 and 14 that were all using the NMR methods and data for characterizing industrially relevant materials. New insights into cryoporometry developed in project 10 also fed projects 12 and 9. The theory projects made substantial progress in the interpretation of NMR data. In particular, using Molecular Dynamics and Monte Carlo methods (Project 1 and levered partner projects separately funded), the Sholl method of calculating relaxation rates in 3 Dimensions was applied to the less symmetric 2 dimensional case more applicable to cements and made “model-free”. New experimental NMR activation energy data was ready to be input to these models. Lattice Boltzmann modeling (projects 2 and 3) have proved to be highly appropriate for evaluating meso-scale transport parameters such as permeability and also for modeling the sorption isotherm. Again there was cross fertilization with the NMR projects. The Lattice Boltzmann projects also provided the cross-over to the more macro-scale projects (4, 11, 12 and 14) that were measuring and modeling water transport in concretes and particularly in cracks. The role and importance of the interface transition zone around aggregates was emergent and a particular point of special focus.
The latest results of the project were presented in the final TRANSCEND conference “water transport in cementitious materials” held in November 2013 in Guildford, UK. This international conference was attended by 89 participants, half of them from outside the TRANSCEND network.
The research project was completed by six training courses, nine official meetings and more than one hundred other meetings. The training courses tackled all aspects of cementitious materials and water transport, not forgetting complementary skills like project management, science outreach and patents. Highlights of this training programme included the professional recording of the lectures “Introduction of cementitious material”, and the public lecture on “Science Outreach to the public” by Jim Al Khalili from the University of Surrey, Nuclear Physicist, broadcaster and Popular science writer who gave an excellent talk on the “Do’s and Don’ts” of talking to the media. As an assignment of this course the fellows carried out an outreach action where they explained their project to a variety of public ranging from school kids with hands-on experiments to university undergraduates and technicians of a cement plant. In doing this, the fellows realized that they could make a real impact by telling their experiences to schoolchildren.
At the end of the project, September 2014, twenty-eight peer-reviewed and thirty-two conference papers have been published or submitted, more papers are in preparation. TRANSCEND has been presented many times at international conferences all over the world. Fourteen PhD or EngD theses have been or will be defended in the near future. However TRANSCEND does not come to an end: as a continuation, one of the fellows, Merlin Etzold (project 2) has been chosen to carry on the mission of consolidating the knowledge gained during these four years. This project funded by the Nanocem consortium (http://www.nanocem.org) will help identify gaps, the need for future research and provide a full picture of recent advances in the field of water transport in cementitious materials.
Further information on TRANSCEND is available at:http://www.nanocem.org/TRANSCEND-MC-ITN.