An Investigation of Suitable Healing Agents for Vascular-Based
Self-Healing in Cementitious Materials
Abstract: Self-healing cementitious materials can extend the service life of structures, improve safety during repair activities and reduce costs with minimal human intervention. Recent advances in self-healing research have shown promise for capsule-based and intrinsic healing systems. However, limited information is available regarding vascular-based self-healing mechanisms. The aim of this work is to compare different commercially available healing agents regarding their suitability in a selfhealing vascular network system by examining a regain in durability and mechanical properties. The healing agents investigated include sodium silicate, two polyurethanes, two water repellent agents and an epoxy resin. Sealing efficiencies above 100% were achieved for most of the healing agents, and both polyurethanes and the epoxy resin showed high regain in strength. The results obtained from this study provide a framework for selecting a healing agent given a specific application, as a healing agent’s rheology and curing properties can affect the optimal geometry and design of a vascular network.
Reference of this article: Shields, Y.; Van Mullem, T.; De Belie, N.; Van Tittelboom, K. An Investigation of Suitable Healing Agents for Vascular-Based Self-Healing in Cementitious Materials. Sustainability 2021, 13, 12948.
Keywords: vascular networks; healing agents; self-healing concrete; durability; mechanical recovery
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
Self-healing bacterial concrete exposed to freezing and thawing associated with chlorides
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
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
Time dependent micromechanical self-healing model for cementitious material
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
Sina Sayadi, Iulia Mihai and Anthony Jefferson: School of Engineering, Cardiff University, Cardiff CF24 3AA, UK
Evaluation of test methods for self-healing concrete with macrocapsules by inter-laboratory testing
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)  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
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
A review of vascular networks for self-healing applications
Abstract: Abstract Increasing awareness for sustainability has led to the development of smart self-healing materials, which can extend the service life and improve safety without human intervention. Vascular networks are observed in biological systems, such as leaf venation and blood vascular systems, and provide inspiration for self-healing mechanisms in engineered systems. Embedding a vascular network in a host material has the advantage of addressing varying magnitudes of damage and allowing for an indefinite replenishment of the healing agent, which are current limitations of intrinsic and capsule-based self-healing systems. These networks are demonstrated in polymer and composite materials, with fabrication methods including removal of sacrificial elements, electrospinning, and an array of additive manufacturing (AM) techniques. Advances in AM allow more complex network configurations to be realized that optimize fluid distribution and healing potential. This review intends to provide a comprehensive overview of the current progress and limitations of the design approaches, fabrication methods, healing mechanisms, and relevant applications of embedded vascular networks. Additionally, significant research gaps and future research directions for vascular self-healing materials are described.
Reference of this article: Shields, Y., De Belie, N., Jefferson, A., & Van Tittelboom, K. (2021). A review of vascular networks for self-healing applications. SMART MATERIALS AND STRUCTURES, 30(6)
Keywords: Self-healing, vascular networks, biomimetic
Yasmina Shields, Nele De Belie & Kim Van Tittelboom: Magnel-Vandepitte Laboratory for Structural Engineering and Building Materials, Ghent University, Belgium
Anthony Jefferston: Cardiff School of Engineering, Cardiff University, United Kingdom