Reservoir-Vascular Tubes Network for Self-Healing Concrete: Performance Analysis by Acoustic Emission, Digital Image Correlation and Ultrasound Velocity
Eleni Tsangouri, Corentin Van Loo, Yasmina Shields, Nele De Belie, Kim Van Tittelboom & Dimitrios G. Aggelis
Abstract: A novel linear reservoir-vascular tubes network is presented in this work and the design efficacy is explored by testing concrete beams loaded on bending and by assessing their damage healing and mechanical recovery. The healing system is composed of additively manufactured polymer components that appear equally effective compared to conventional ceramic tubes since the 3D printed polymer-tubes instantly break upon cracking. It is shown that bulk reservoirs embedded into concrete can deviate cracks and detrimentally affect the concrete’s resistance to failure. The crack formation and re-opening is monitored by acoustic emission (AE) and digital image correlation (DIC) concluding that initial brittle cracking is shifted after healing to a pseudo-ductile crack re-opening with extended post-softening. The sealed cracks show significant strength and toughness recovery (i.e., above 80% of the original value) escorted also by an ultrasound pulse velocity (UPV) increase (up to 126% relative to the damage state) after a healing intervention. The work critically reports on obstructions of the current design: (i) the network tubes are clogged although the agent was flushed out of the network after healing and as a result re-healing is unattainable; and (ii) vacuum spaces are formed during casting underneath the network tubes, due to limited vibration aiming on the tubes’ tightness, but also due to inefficient aggregates settlement, leading to a strength decrease. This work calls attention to the impact of vascular networks design and performance on a complex cracks network and fracture zone development. .
Reference of this article: Tsangouri, E.; Van Loo, C.; Shields, Y.; De Belie, N.; Van Tittelboom, K.; Aggelis, D.G. Reservoir-Vascular Tubes Network for Self-Healing Concrete: Performance Analysis by Acoustic Emission, Digital Image Correlation and Ultrasound Velocity. Appl. Sci. 2022, 12, 4821
DOI: 110.3390/app12104821
Keywords: concrete; self-healing; cracking; vascular network; reservoir; acoustic emission; digital image correlation; ultrasound pulse velocity
Affiliations:
Eleni Tsangouri, Corentin Van Loo, Dimitros G Aggelis:Department Mechanics of Materials and Constructions (MeMC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
Yasmina Shields, Tim Van Mullem, Nele De Belie & Kim Van Tittelboom: Magnel-Vandepitte Laboratory, Department of Structural Engineering and Building Materials, Faculty of
Engineering and Architecture, Ghent University, Technologiepark Zwijnaarde 60, B-9052 Ghent, Belgium
The full article can be found here: https://doi.org/10.3390/app12104821
Effects of bacteria-embedded polylactic acid (PLA) capsules on fracture properties of strain hardening cementitious composite (SHCC)
Shan He, Shizhe Zhang, Mladna Lukovic and Erik Schlangen
Abstract: Strain hardening cementitious composite (SHCC) is a special class of ultra-ductile material which has autogenous self-healing capability due to its intrinsic tight crack widths. To further improve its healing ability, healing agent (HA) can be incorporated in SHCC, enabling it also the autonomous self-healing mechanism. In this study, the effects of adding bacteria-embedded polylactic acid (PLA) capsules on the mechanical properties of SHCC with different amounts of HA (i.e., 1.25%, 2.5%, 5% by weight to binder) were investigated. Experiments were conducted to examine the composite performance, matrix properties and single fiber pullout behavior of the SHCCs, followed by microscopy characterization of the fiber/matrix interface microstructure. Results show that the inclusion of the PLA-HA up to 5% by weight to binder influenced the tensile performance (i.e., tensile strength and ductility) of SHCC only to a very small extent but significantly reduced the average residual crack widths. The inclusion of HA at a high dosage (5%) increased the crack tip toughness (Jtip) of the matrix by lowering elastic modulus and increasing fracture toughness. Single fiber pullout results show that the fiber/matrix bond properties were enhanced by the addition of the HA, which can be attributed to the formation of a denser interfacial transition zone (ITZ) with less calcium hydroxide crystals as revealed by the scanning electron microscope (SEM) micrographs. The improved bond properties led to higher fiber bridging complementary energy and thus partially sustained the tensile strain capacity as verified by the micromechanical model.
Reference of this article: Shan He, Shizhe Zhang, Mladna Lukovic and Erik Schlangen (2022), Effects of bacteria-embedded polylactic acid (PLA) capsules on fracture properties of strain hardening cementitious composite (SHCC) , Engineering Fracture Mechanics, Volume 268, Elsevier, ISSN 0013-7944
Affiliations:
Shan He, Shizhe Zhang and Erik Schlangen: Microlab, Faculty of Civil Engineering and Geosciences, Delft University of Technology, 2628 CN Delft, the Netherlands
Mladena Lukovic: Concrete Structures, Faculty of Civil Engineering and Geosciences, Delft University of Technology, 2628 CN Delft, the Netherlands
The full article can be found here: https://doi.org/10.1016/j.engfracmech.2022.108480
Evaluation of test methods for self-healing concrete with macrocapsules by inter-laboratory testing
Tim Van Mullem, Giovanni Anglani, Hanne Vanoutrive, Girts Bumanis, Chrysoula Litina, Marta Dudek, Arkadiusz Kwiecien, Abir Al-Tabbaa, Diana Bajare, Teresa Stryszewska, Robby Caspeele, Kim Van Tittelboom, Jean Marc Tulliani, Elke Gruyaert, Paola Antonaci and Nele De Belie
Abstract: Self-healing of concrete is a promising way to increase the service life of structures. Innovative research is being performed, yet it is difficult to compare results due to a lack of standardised test methods. In the framework of the COST action SARCOS (CA15202) [1] six different inter- laboratory tests are being executed, in which different test methods are being evaluated for six self-healing approaches. Here, the results of the inter-laboratory test concerning mortar and concrete with macrocapsules filled with a polyurethane healing agent will be discussed. The specimens were manufactured in one laboratory and then shipped to the other five participating laboratories. All six laboratories evaluated two test methods: a water permeability test and a capillary water absorption test. For the water permeability test, mortar specimens were cracked and afterwards their crack width was controlled using an active control technique. Due to the active crack control, the crack width of 90% of the samples deviated by less than 10 μm from the target of 300 μm. This made it more straightforward to compare the permeability test results, which indicated a similar sealing efficiency for several of the laboratories. For the capillary water absorption test, concrete specimens were cracked in a crack-width-controlled three-point bending test setup without active control after unloading. Compared to the water permeability specimens, there was a lot more variation on the crack width of the capillary water absorption specimens. The variability on the crack width and differences in quality of waterproofing resulted in diverging findings in the capillary water absorption test.
Reference of this article: Tim Van Mullem, Giovanni Anglani, Hanne Vanoutrive, Girts Bumanis, Chrysoula Litina, Marta Dudek, Arkadiusz Kwiecien, Abir Al-Tabbaa, Diana Bajare, Teresa Stryszewska, Robby Caspeele, Kim Van Tittelboom, Jean Marc Tulliani, Elke Gruyaert, Paola Antonaci and Nele De Belie (2021), Evaluation of test methods for self-healing concrete with macrocapsules by inter-laboratory testing, Proceedings Resilient Materials 4 Life 2020 (RM4L2020), Maddalena R, Wright-Syed M, (RM4L Eds), pp. 180-185, Cardiff, UK, 20-22 Sep 2021, ISBN 978-1-3999-0832-0
Affiliations:
Tim Van Mullem, Robby Caspeele, Kim Van Tittelboom and Nele De Belie: Magnel-Vandepitte Laboratory, Department of Structural Engineering and Building Materials, Ghent University, Belgium
Giovanni Anglani, Jean Marc Tulliani and Paola Antonaci: Politecnico di Torino, Italy
Hanne Vanoutrive and Elke Gruyaert: KU Leuven - Ghent Technology Campus, Belgium
Girts Bumanis and Diana Bajare: Riga Technical University, Latvia
Chrysoula Litina and Abir Al-Tabbaa: University of Cambridge, United Kingdom
Marta Dudek, Arkadiusz Kwiecien and Teresa Stryszewska: Cracow University of Technology, Poland
The full article can be found here: http://orca.cardiff.ac.uk/id/eprint/145287 on pages 180-185
Time dependent micromechanical self-healing model for cementitious material
Sina Sayadi, Iulia Mihai, Anthony Jefferson
Abstract: The need for more sustainable systems for construction applications has led researchers to develop a range of self-healing materials for designing or repairing structures. Unsurprisingly, concrete, as the most used construction material, has received considerable attention from the biomimetic research community. Despite much research over the past two decades, there is not yet a comprehensive reliable model for predicting the behaviour of self-healing concrete under a range of conditions. Concrete itself is a complex heterogeneous brittle material that is challenging to simulate. When healing is also considered, its behaviour becomes even more complex. This contribution presents a constitutive model based on a micromechanical formulation, with time dependent cracking and healing functions. The model employs an Eshelbian solution, as well as a range of homogenization techniques, to estimate overall properties and the nonlinear response of self-healing concrete. A key assumption in the formulation is that the new healing material forms in a stress-free state. The initial results show that the mechanical healing efficiency and post-healed response are strongly dependent on the properties of the matrix and healing materials, curing time of the healing agent and the damage threshold at which healing is activated.
Reference of this article: Sina Sayadi, Iulia Mihai and Anthony Jefferson (2021), Self-healing bacterial concrete exposed to freezing and thawing associated with chlorides, Proceedings Resilient Materials 4 Life 2020 (RM4L2020), Maddalena R, Wright-Syed M, (RM4L Eds), pp. 105-109, Cardiff, UK, 20-22 Sep 2021, ISBN 978-1-3999-0832-0
Affiliations:
Sina Sayadi, Iulia Mihai and Anthony Jefferson: School of Engineering, Cardiff University, Cardiff CF24 3AA, UK
The full article can be found here: http://orca.cardiff.ac.uk/id/eprint/145287 on pages 105-109
Self-healing bacterial concrete exposed to freezing and thawing associated with chlorides
Vanessa Giaretton Cappellesso, Tim Van Mullem, Elke Gruyaert, Kim Van Tittelboom and Nele De Belie
Abstract: Self-healing concrete and preventive repair of structures will slow down the development of cracks and/or arrest the ingress of aggressive agents. When the cracks are closed or a decrease in crack width is achieved, this will be associated with improved durability of the structure. This paper describes the literature review and inter-laboratory comparison carried out within the COST Action CA15202 (SARCOS), as well as the research planned within the recently started International Training Network SMARTINCS.
Reference of this article: Vanessa Giaretton Cappellesso, Tim Van Mullem, Elke Gruyaert, Kim Van Tittelboom and Nele De Belie (2021), Self-healing bacterial concrete exposed to freezing and thawing associated with chlorides, Proceedings Resilient Materials 4 Life 2020 (RM4L2020), Maddalena R, Wright-Syed M, (RM4L Eds), pp. 241-246, Cardiff, UK, 20-22 Sep 2021, ISBN 978-1-3999-0832-0
Affiliations:
Vanessa Giaretton Cappellesso, Tim Van Mullem, Nele De Belie, Kim Van Tittelboom: Ghent University, Department of Structural Engineering and Building Materials, Technologiepark Zwijnaarde 60, 9052 Gent, BE
Vanessa Giaretton Cappellesso and Elke Gruyaert: KU Leuven, Department of Civil Engineering, Materials and Constructions, Ghent Technology Campus, Gebroeders De Smetstraat 1, 9000 Ghent, BE
The full article can be found here: http://orca.cardiff.ac.uk/id/eprint/145287 on pages 241-246