10/12/2021
Marie Skłodowska-Curie Actions

MSCA-COFUND-CLEAR-Doc - PhD Position #CD21-07: External Sulfate Attack (ESA) - Chemo-mechanical degradation that undermines the structural integrity and safety of concrete

This job offer has expired


  • ORGANISATION/COMPANY
    Université Gustave Eiffel
  • RESEARCH FIELD
    Engineering
  • RESEARCHER PROFILE
    First Stage Researcher (R1)
  • APPLICATION DEADLINE
    21/03/2022 17:00 - Europe/Brussels
  • LOCATION
    France › Marne-La-Vallée
  • TYPE OF CONTRACT
    Temporary
  • JOB STATUS
    Full-time
  • HOURS PER WEEK
    35
  • OFFER STARTING DATE
    01/10/2022
  • EU RESEARCH FRAMEWORK PROGRAMME
    H2020 / Marie Skłodowska-Curie Actions COFUND
  • MARIE CURIE GRANT AGREEMENT NUMBER
    101034248

OFFER DESCRIPTION

Research environment

Université Gustave-Eiffel is a French university specialized in the study of cities and transportation. It resulted from the fusion of the University of Paris-Est Marne-la-Vallée, the IFSTTAR national research institute and the close association of three engineering schools and a school of architecture. The FM2D laboratory is developing research on the formulation and durability of civil engineering construction materials. Relying on its internationally recognized scientific expertise in predicting the durability of traditional cementitious materials used in existing structures, the Laboratory contributes to the development of innovative formulations of mineral-binder materials with low environmental impact that are of high durability, with a view to their use as eco-materials for civil engineering construction.

The Institute of Construction and Building Materials (WIB) at the Technical University of Darmstadt focuses on research in the fields of materials technology, building physics and building chemistry, with the sustainability of mineral binders as one of the main research areas. Research activities focus on the development of environmentally friendly binder systems, as well as other topics such as geopolymers, reactivity of binders, transport mechanisms, durability and acid resistivity. The scientific activities take place on a national and international level as basic or applied research.

Cerema (which stands for Centre for Studies and Expertise on Risks, the Environment, Mobility and Urban Planning) is the major French public agency for developing public expertise in the fields of urban planning, regional cohesion and ecological and energy transition for resilient and climate-neutral cities and regions. The GeoCod research team is developing experimental and numerical techniques in order to predict the physico-chemical and mechanical behaviors of cement-based materials and treated soils.

Job description

The presence of sulfate in groundwater is a matter of great concern since it affects the durability of cement-based materials or cement treated-soil, a technique increasingly employed to participate in the fight against climate change by improving the quality of on-site materials and reducing the need for imported materials. The range of structures affected by this is wide since it covers foundation concretes, tunnels, treated backfill. The mechanism causing the sulfate to propagate into the porous media changes the chemical composition of the initial pore solution, disturbing the local thermodynamic equilibrium. As a consequence, a substantial chemical and mechanical degradation may lead to expansion, cracks, decohesion and finally to a destruction of the cementitious matrix [1]. Experimental observations show a period of induction or initiation (or latency period) during which very few macroscopic deformations appear [2-4]. An expansion period follows and leads to cracks and material degradation. Ettringite precipitation (and possibly gypsum) is often considered responsible for expansion [5]. Nevertheless, the relationship between the formation of ettringite and macroscopic degradation with expansion and scaling is not well understood, a fortiori, in new cement compositions and new concrete mix-designs.

Studies focusing on the mineral and ionic species evolutions due to ESA have been undertaken from the chemo-transport viewpoint with sophisticated chemical codes [6-8]. They can be useful to deepen our understanding of the processes that take place during sulfate interaction. However, such models need investigations in order to improve their ability to consider decalcification of C-S-H and ettringite precipitation locations, especially for cementitious materials with new additions. Furthermore, the coupled approach able to estimate mechanical degradation exists in few works but improvement remains in order to explain such a complex mechanism.

The position will focus on the mineral and ionic species evolutions due to ESA undertaken from a chemo-transport point of view with advanced chemical codes. A deeper understanding of the processes that take place during sulfate interaction will be pursued. For this, models need to be evaluated on their ability to simulate the decalcification of C-S-H and ettringite precipitation at critical locations, especially for cementitious materials with new additions. Furthermore, a coupled approach able to estimate mechanical degradation will be employed to explain such a complex mechanism.

Tasks:

- Experimental observation of induction or initiation of macroscopic deformations.

- Observing the expansion period leading to cracks and material degradation.

- Study the ettringite precipitation (and possibly gypsum) responsible for expansion.

- Study the deleterious mechanism of ESA in C-S-H gel, along with the relationship between ettringite formation and macroscopic degradation with expansion and scaling.

Objective:

The objective of the PhD position is to improve the description of the chemical reactions involving the main characteristic minerals and species in the pore solution. A reactive transport mechanism will be developed, applicable to new cementitious materials, associated with an approach to reproducing the mechanical effects of the microstructural evolution. For that purpose, a reactive transport code and homogeneization techniques will be employed based on previous developments of GeoCod research team, while the numerical results will be compared with experimental results available from the project and from literature."

International Mobility:

A 6-month secondment at University of Darmstadt, WIB Institute (Germany).

For more information, contact the PhD thesis supervisor.

 

More Information

Benefits

  • High-quality doctoral training rewarded by a PhD degree, delivered by Université Gustave Eiffel
  • Access to cutting-edge infrastructures for research & innovation.
  • Appointment for a period of 36 months based on a salary of 2 700 € (gross salary per month).
  • Job contract under the French labour legislation in force, respecting health and safety, and social security: 35 hours per week contract, 25 days of annual leave per year.
  • International mobility will be mandatory
  • An international environment supported by the adherence to the European Charter & Code.
  • Access to dedicated CLEAR-Doc trainings with a strong interdisciplinary focus, together with a Career development Plan.

Eligibility criteria

  • At the time of the deadline, applicants must be in possession or finalizing their Master’s degree or equivalent/postgraduate degree. At the time of recruitment, applicants must be in possession of their Master’s degree or equivalent/postgraduate degree which would formally entitle to embark on a doctorate.
  • At the time of the deadline, applicants must be in the first four years (full-time equivalent research experience) of their research career (career breaks excluded) and not yet been awarded a doctoral degree. Career breaks refer to periods of time where the candidate was not active in research, regardless of his/her employment status (sick leave, maternity leave etc). Short stays such as holidays and/or compulsory national service are not taken into account.
  • At the time of the deadline, applicants must not have resided or carried out their main activity (work, studies, etc.) in France for more than 12 months in the 3 years immediately prior to the call deadline.
  • Applicants must be available to start the programme on schedule (around 1st October 2022).

Selection process

Additional comments

  • The First step before applying is contacting the PhD supervisor. You will not be able to apply without an acceptation letter from the PhD supervisor.
  • Please contact the PhD supervisor for any additional detail on job offer.
  • There are no restrictions concerning the age, gender or nationality of the candidates. Applicants with career breaks or variations in the chronological sequence of their career, with mobility experience or with interdisciplinary background or private sector experience are welcome to apply.
  • Support service is available during every step of the application process by email: clear-doc@univ-eiffel.fr

 

Web site for additional job details

Offer Requirements

  • REQUIRED LANGUAGES
    ENGLISH: Excellent
    FRENCH: Basic

Skills/Qualifications

  • At the time of the deadline, applicants must be in possession or finalizing their Master’s degree or equivalent/postgraduate degree.
  • At the time of recruitment, applicants must be in possession of their Master’s degree or equivalent/postgraduate degree which would formally entitle to embark on a doctorate.

Work location(s)
1 position(s) available at
Université Gustave Eiffel
France
Marne-La-Vallée
77454
5, Boulevard Descartes

EURAXESS offer ID: 718016

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