Repair of Concrete in Environments with Chlorides or Subjected to Freeze-Thaw Scaling
Vanessa Cappellesso, Tim Van Mullem, Elke Gruyaert, Kim Van Tittelboom & Nele De Belie
Abstract: Crack formation further decreases the durability of structures when chloride ions associated with freezing temperatures are present. Therefore, preventing the entry of aggressiveness is imperative to guarantee the service life. Repair actions might recover the liquid-tightness when cracks occur. A water repellent agent (WRA) and a sodium silicate (SS) solution were applied to self-repair cracks in the current research. The repair occurred by manual injection of cracks to obtain a proof-of-concept for the possible self-healing efficiency. Two extreme conditions have been assessed after the healing period, the first referring to continuous immersion in a chloride solution, and the second applying freeze-thaw conditions with de-icing salts. Chloride ingress was evaluated through the colour change boundary test. In addition, optical microscopy analysis was used to measure the crack width and to observe differences before and after exposure. SS prevented the chloride ingress through the crack in both conditions. However, the method used to verify chloride ingress did not give consistent results for the WRA due to its hydrophobicity. Microscopic analysis showed that both agents could avoid chloride ingress in the cracks. For the samples exposed to freeze-thaw cycles, only chloride ingress measurement could indicate the healing performance as the scaling destroyed the surface.
Reference of this article: Cappellesso, V.G., Van Mullem, T., Gruyaert, E., Van Tittelboom, K., De Belie, N. (2023). Repair of Concrete in Environments with Chlorides or Subjected to Freeze-Thaw Scaling. In: Escalante-Garcia, J.I., Castro Borges, P., Duran-Herrera, A. (eds) Proceedings of the 75th RILEM Annual Week 2021. RW 2021. RILEM Bookseries, vol 40. Springer, Cham.
Affiliations:
Vanessa Cappellesso, Tim Van Mullem, Kim Van Tittelboom and Nele De Belie: Magnel-Vandepitte Laboratory, Department of Structural Engineering and Building Materials, Faculty of Engineering and Architecture,
Ghent University, Ghent, Belgium
Vanessa Cappellesso and Elke Gruyaert: Department of Civil Engineering, Materials and Constructions, KU Leuven, Ghent, Belgium
This email address is being protected from spambots. You need JavaScript enabled to view it.
The full article can be found here: https://doi.org/10.1007/978-3-031-21735-7_25
Bond behaviour evaluation between steel reinforcement and self-healing concrete containing non-axenic biomasses
Harry Hermawan, Mustafa Mert Tezer, Willy Verstraete, Nele De Belie, Pedro Serna and Elke Gruyaert
Abstract: Although steel reinforcements are used to withstand tensile forces in concrete, cracks are an unavoidable phenomenon. The presence of cracks, in fact, increases the risk for lowering the service life and durability of concrete structures. A critical issue occurs when due to splitting forces, cracks appear in concrete along the tensioned rebars which damage the bonding between the steel and concrete matrix. As a mitigation plan, the cracks should be healed at short notice and the bonding has to be recovered by the potential use of healing agents. This paper aims to investigate the bond behaviour of steel reinforcement in self-healing concrete. Two biomasses were employed as healing agents namely HTN (bacteria-based) and YEAST (fungi-based). The fresh and hardened properties of the normal and self-healing concretes were initially evaluated. The bond properties were investigated by performing pull-out tests on three different states of concrete: uncracked, cracked, and healed. Results revealed that the additions of biomasses did not induce negative effects on the compressive strength of hardened concrete. Moreover, the average bond strength of uncracked concretes containing HTN and YEAST improved by 20% and 8%, respectively, as compared with normal concrete. The introduction of a crack caused a significant reduction in bond strength regardless of the addition of healing agents. Nevertheless, it was found that the bond strength was slightly recovered after healing under water immersion.
Reference of this article: Bond behaviour evaluation between steel reinforcement and self-healing concrete containing non-axenic biomasses Harry Hermawan, Mustafa Mert Tezer, Willy Verstraete, Nele de Belie, Pedro Serna, Elke Gruyaert MATEC Web Conf. 378 02009 (2023)
Affiliations:
Harry Hermawan and Elke Gruyaert: KU Leuven, Ghent Technology Campus, Department of Civil Engineering, Materials and Constructions, Gebroeders De Smetstraat 1, 9000 Ghent, Belgium
Harry Hermawan and Pedro Serna: Instituto de Ciencia y Tecnología Del Hormigón (ICITECH), Universitat Politècnica de València, Camino de Vera S/n, 46022, Valencia, Spain
Mustafa Mert Tezer and Nele De Belie Ghent University, Department of Structural Engineering and Building Materials, Magnel-Vandepitte Laboratory, Tech Lane Ghent Science Park, Campus A, Technologiepark Zwijnaarde 60, B-9052, Ghent, Belgium
Mustafa Maer Tezer and Willy Verstraete: AVECOM nv, Industrieweg 122P, 9032 Wondelgem, Belgium
This email address is being protected from spambots. You need JavaScript enabled to view it.
The full article can be found here: https://doi.org/10.1051/matecconf/202337802009
Applicability of cementitious capsules in concrete production: initial assessment on capsule robustness, mechanical and self-sealing properties of concrete
Harry Hermawan, Alicia Simons, Silke Teirlynck, Pedro Serna, Peter Minne, Giovanni Anglani, Jean-Marc Tulliani, Paola Antonaci and Elke Gruyaert
Abstract: The use of macrocapsules in self-healing applications offers a potential benefit by carrying a larger amount of healing agent in comparison with microcapsules. However, the application of macrocapsules is still limited to paste and mortar levels on lab-scale. This is due to a concern that most capsules might be broken when mixed with concrete components. In this study, cementitious tubular capsules were used and they were considered as a partial replacement of coarse aggregates (2 vol% gravel). The capsules have a dimension of 54 mm and 9 mm in length and outer diameter, respectively. A water-repellent agent (WRA) was entrapped in the capsules as a proposed agent to seal the crack. Initial results revealed high survivability of capsules during concrete mixing: 100% survival ratio when tested in a drum mixer and 70–95% when tested in a planetary mixer. The mechanical and self-sealing properties of concrete containing embedded capsules were evaluated. With the addition of capsules, around 8% reduction of compressive strength was noticed, but no further effect on splitting tensile strength was detected as compared with concrete without capsules. Ultrasonic pulse velocity (UPV) tests confirmed that the presence of capsules also did not significantly affect the compactness of the hardened concrete. Furthermore, the embedded capsules were able to break when a crack was introduced and it was found that 90% sealing efficiency was achieved by capsule-based concrete as a result of the successful release of sealing agent into the crack.
Reference of this article: Applicability of cementitious capsules in concrete production: initial assessment on capsule robustness, mechanical and self-sealing properties of concrete Harry Hermawan, Alicia Simons, Silke Teirlynck, Pedro Serna, Peter Minne, Giovanni Anglani, Jean-Marc Tulliani, Paola Antonaci and Elke Gruyaert MATEC Web Conf., 378 (2023) 02013
Affiliations:
Harry Hermawan, Alicia Simons, Silke Teirlynck, Peter Minne and Elke Gruyaert: KU Leuven, Ghent Technology Campus, Department of Civil Engineering, Materials and Constructions, Gebroeders De Smetstraat 1, 9000 Ghent, Belgium
Pedro Serna: Instituto de Ciencia y Tecnología Del Hormigón (ICITECH), Universitat Politècnica de València, Camino de Vera S/n, 46022, Valencia, Spain
Giovanni Anglani and Paola Antonaci: Department of Structural, Geotechnical and Building Engineering (DISEG), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
Jean-Marc Tulliani: INSTM Research Unit PoliTO-LINCE Laboratory, Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
This email address is being protected from spambots. You need JavaScript enabled to view it.
The full article can be found here: https://doi.org/10.1051/matecconf/202337802013
Bacteria-based self-healing concrete exposed to frost salt scaling
Vanessa Cappellesso, Tim Van Mullem, Elke Gruyaert, Kim Van Tittelboom & Nele De Belie
Abstract: elf-healing concrete is an innovative and promising technology to increase the durability and service life of the structure by limiting the influence of aggressive attacks. However, knowledge on the performance in realistic conditions is limited. This paper presents the benefits of introducing a bacteria-based healing agent in concrete to enable self-healing, assessed under frost salt scaling conditions. Durability tests such as scaling, water permeability and chloride ingress were performed. In addition, a microstructural analysis was realized based on mercury intrusion porosimetry (MIP), fluorescence microscopy, thin section analysis, scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. The bacteria enhanced the concrete properties, resulting in a 90% higher frost salt scaling resistance than the reference concrete and reduced chloride penetration by 46%. The bacteria-based concrete furthermore showed fewer microcracks. However, chloride penetration through cracks could not be prevented since only partial crack healing was achieved for the studied mix design.
Reference of this article: Vanessa Giaretton Cappellesso, Tim Van Mullem, Elke Gruyaert, Kim Van Tittelboom, Nele De Belie, Bacteria-based self-healing concrete exposed to frost salt scaling, Cement and Concrete Composites, Volume 139, 2023, 105016, ISSN 0958-9465
Affiliations:
Vanessa Cappellesso, Tim Van Mullem, Kim Van Tittelboom and Nele De Belie: Magnel-Vandepitte Laboratory, Department of Structural Engineering and Building Materials, Faculty of Engineering and Architecture,
Ghent University, Ghent, Belgium
Vanessa Cappellesso and Elke Gruyaert: Department of Civil Engineering, Materials and Constructions, KU Leuven, Ghent, Belgium
This email address is being protected from spambots. You need JavaScript enabled to view it.
The full article can be found here: https://doi.org/10.1016/j.cemconcomp.2023.105016
A New Method to Quantitatively Characterize the Porosity of Fiber/Matrix Interfacial Transition Zone (ITZ) via Longitudinal Cross-Sections
Shan He, Minfei Liang, En-hua Yang and Erik Schlangen
Abstract: The properties of the interfacial transition zone (ITZ) between microfiber and cement-based matrix are of primary significance for the overall behavior of strain hardening cementitious composites (SHCCs). However, due to the relatively small diameter of polymeric microfibers (e.g., PVA fiber), it is technically difficult to obtain quantitative and representative information of the properties of the ITZ. In the current study, a new method that is able to quantitatively characterize the microstructural features of the ITZ surrounding a well-aligned microfiber was reported. With the method, the porosity gradients within the ITZs between PVA fiber and cement paste matrices with different water to cement (w/c) ratios were determined. The results show that the matrix surrounding a microfiber were more porous than the bulk matrix. The thickness of this porous region can extend up to 100 microns away from the fiber surface even at a relatively low water to cement ratio (w/c = 0.3). It is thus believed that the method could facilitate the investigation and modification of fiber/matrix bond properties and also contribute to the development of SHCC with superior properties.
Reference of this article: He, S., Liang, M., Yang, Eh., Schlangen, E. (2023). A New Method to Quantitatively Characterize the Porosity of Fiber/Matrix Interfacial Transition Zone (ITZ) via Longitudinal Cross-Sections. In: Kunieda, M., Kanakubo, T., Kanda, T., Kobayashi, K. (eds) Strain Hardening Cementitious Composites. SHCC 2022. RILEM Bookseries, vol 39. Springer, Cham. https://doi.org/10.1007/978-3-031-15805-6_14
Affiliations:
Shan He,Minfei Liang and Erik Schlangen: Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft 2628 CN, the Netherlands
En-hua Yang: School of Civil and Environmental Engineering, Nanyang Technological University, Singapore, 639797, Singapore
This email address is being protected from spambots. You need JavaScript enabled to view it.
The full article can be found here: https://doi.org/10.1007/978-3-031-15805-6_14