Cement; Concrete; Cracking; Creep; Shrinkage; Durability; Sustainability; Nuclear Magnetic Resonance; Modeling
Wyrzykowski Mateusz, Gajewicz-Jaromin Agata M., McDonald Peter J., Dunstan David J., Scrivener Karen L., Lura Pietro (2019), Water Redistribution–Microdiffusion in Cement Paste under Mechanical Loading Evidenced by 1 H NMR, in The Journal of Physical Chemistry C
, 123(26), 16153-16163.
Wyrzykowski Mateusz, Scrivener Karen, Lura Pietro (2019), Basic creep of cement paste at early age - the role of cement hydration, in Cement and Concrete Research
, 116, 191-201.
Hu Zhangli, Wyrzykowski Mateusz, Scrivener Karen, Lura Pietro (2018), A novel method to predict internal relative humidity in cementitious materials by H-1 NMR, in CEMENT AND CONCRETE RESEARCH
, 104, 80-93.
Wyrzykowski Mateusz, McDonald Peter J, Scrivener Karen, Lura Pietro (2017), Water Redistribution within the Microstructure of Cementitious Materials due to Temperature Changes Studied with 1H NMR, in The Journal of Physical Chemistry C
Hu Zhangli, Hilaire Adrien, Wyrzykowski Mateusz, Scrivener Karen, Lura Pietro (2017), Elastic and Visco-Elastic Behavior of Cementitious Materials at Early Ages, in Poromechanics 2017 - Proceedings of the 6th Biot Conference on Poromechanics
, Paris, FranceASCE Library, Reston, VA.
Wyrzykowski Mateusz, Di Bella Carmelo, Lura Pietro (2017), Prediction of Drying Shrinkage of Cement-Based Mortars with Poroelastic Approaches—A Critical Review, in Poromechanics 2017 - Proceedings of the 6th Biot Conference on Poromechanics
, Paris, FranceASCE Library, Reston, VA.
Concrete is the most important building material worldwide. In Switzerland alone, 38 Mio tons were produced in 2013, with a revenue of 2’360 Mio CHF. About 5-7% of anthropogenic CO2 emission comes only from cement industry. More sustainable concrete is necessary for addressing the environmental and energy supply challenges of today and tomorrow’s society. This can be achieved by using high performance concretes (HPC) and/or cements with replacement of cement clinker with supplementary cementitious materials (SCM). However, concretes with high contents of SCM, in particular HPC, have higher risk of cracking in the first days to weeks after placing. The current poor understanding of the fundamental mechanisms underlying early-age cracking is in fact delaying the acceptance of modern concretes. Cracking is caused by restrained deformations occurring at loading, drying and temperature changes. While the stresses build up due to restrained deformations, they are relaxed by viscoelastic deformations of the concrete (manifesting as creep and stress relaxation). Short-term stress relaxation at early ages can reduce the theoretical elastic restraint stresses by 50-80% and avoid cracking. However, despite the large body of studies on concrete cracking, little is known about the mechanisms underlying creep. This project focuses on the role of short-term creep accompanying mechanical loading, shrinkage and thermal deformations. An advancement in fundamental understanding of creep mechanisms will be achieved by clarifying the role of water redistribution during mechanical loading, drying and temperature changes. Until recently, no experimental evidence of changes in the moisture state of cementitious materials accompanying mechanical loading and creep had been produced. However, a recent study by the applicant shows the first direct evidence of such phenomenon. The missing part regards however the explicit observation of water redistribution. In the last couple of years, new possibilities for in-situ non-destructive studying of moisture distribution in cementitious materials were opened with Nuclear Magnetic Resonance (NMR) relaxometry, in particular in a collaboration between the University of Surrey and EPF Lausanne (EPFL). The breakthrough approach of the present proposal consists in studying water redistribution upon loading with in-situ NMR relaxometry combined with the measurements of RH and deformations due to creep. It is expected that this approach will cast new light on the mechanisms causing creep/relaxation and on their influence on concrete cracking. This is only possible by taking advantage of the state-of-the-art experimental facilities for studying concrete deformations available at Empa (main host), combined with the NMR at EPFL (co-host) and University of Surrey (visits). The applicant will face a major experimental challenge that has not been addressed so far for studying concrete creep; in the project special loading cells will be constructed to load the samples with pressure, drying and temperature changes while performing NMR measurements, to enable in-situ following of water redistribution responsible for short term creep. In parallel, cutting-edge modelling approaches will be developed for description of short-term creep in collaboration with Vienna University of Technology (visits). This creep model will be then integrated in a poromechanical framework for predictions of concrete creep and relaxation. The high impact of the proposed project will be achieved thanks to combining the efforts of the four academic institutions involved, and the dissemination and outreach activities within the networks: RILEM, Nanocem and COST TU1404. The applicant will be appointed at Empa and will spend about 50% of his working time (on a regular basis) at EPFL, where he will run the experimental work with NMR. This dynamic mobility program will enable intense research synergies which are essential for achieving a breakthrough in the prediction of concrete creep. It will also constitute an important step in the career of the applicant, enhancing his professional development in technical and scientific skills, as well as extending his professional network and recognition. These assets will highly increase the scientific competitiveness of the applicant in the research field worldwide.