Experimental investigation on the bond behaviour of steel reinforcement in self-healing concrete
Harry Hermawan, Virginie Wiktor, Elke Gruyaert and Pedro Serna
Abstract: The appearance of cracks in structural reinforced concrete is inevitable and when out of control, it can be the cause of concrete failure. The ingress of water and harmful substances via the cracks is critical as the embedded steel reinforcements in the concrete can be corroded. Crack formation will directly weaken the bond between the reinforcing bar and concrete. To mitigate this issue, cracks should be repaired and closed relatively fast and this can potentially be obtained by incorporating self-healing technologies. Self-healing concrete demonstrates a good healing efficiency by the use of smart materials which allow for autonomous healing or enhance the autogenous healing mechanism of concrete. However, it is questioned whether the precipitates only artificially close the crack or also contribute to improve the bond with the reinforcement. In this study, an experimental investigation was conducted to evaluate the bond properties of self-healing concrete by means of pull-out tests. Four types of healing agents were used including two non-axenic biomass agents (HTN and YEAST) and two commercial agents (crystalline admixture and bacteria (CA and BAC)). The fresh properties and mechanical properties of the concrete including the healing agents were initially investigated. Pull-out tests were executed on uncracked, cracked and healed specimens. Two healing periods (28 and 112 days water immersion) were considered to evaluate the effect of healing time on bond recovery. Test results confirm that the addition of healing agents induced a better improvement of bond properties of steel reinforcement in uncracked concretes with respect to the reference concrete (no healing agent added). The highest bond strength enhancement by 57% on uncracked concrete was obtained with the addition of CA, while the inclusion of other agents such BAC, HTN and YEAST also possessed the bond strength improvement by 47, 21 and 7%, respectively. The presence of a longitudinal crack in concrete significantly reduced the bond strength up to 80% and this effect was not significantly affected by the crack size, when considering cracks in the range of 200─500 µm, and the introduction of healing agents. Nevertheless, the bond properties were slightly recovered after healing due to self-healing effects and formation of healing products in the crack was clearly visible.
Reference of this article: Harry Hermawan, Virginie Wiktor, Elke Gruyaert, Pedro Serna, Experimental investigation on the bond behaviour of steel reinforcement in self-healing concrete, Construction and Building Materials, Volume 383, 2023, 131378, ISSN 0950-0618
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
Virginie Wiktor: Cugla B.V., R&D center, Rudonk 6b, 4824 AJ Breda, the Netherlands
Pedro Serna: Instituto de Ciencia y Tecnología Del Hormigón (ICITECH), Universitat Politècnica de València, Camino de Vera S/n, 46022, Valencia, Spain
The full article can be found here: https://doi.org/10.1016/j.conbuildmat.2023.131378
Influence of Crystalline Admixtures and Bacteria on the Fresh Properties of Self-healing Concrete
Harry Hermawan, Peter Minne, Enricomaria Gastaldo Brac, Virginie Wiktor, Pedro Serna and Elke Gruyaert
Abstract: Concrete is undeniably susceptible to cracking due to its low tensile strength in spite of its ability to withstand high compressive stresses. Cracks may jeopardize the concrete core and reinforcements due to the ingress of water and aggressive substances. A promising technique to effectively seal cracks in hardened concrete is using a self-healing technology by introducing healing agents to the fresh concrete mixes. Crystalline admixtures and bacteria emerge as promising self-healing agents to promote stimulated autogenous healing and autonomous healing mechanisms, respectively, improving simultaneously the durability of the concrete. Healing agents are mostly added on top of the normal mix without changing the mix design of the concrete, while in fact, it may induce considerable effects on the fresh and hardened properties of concrete. In this study, two types of cement (CEM I 52.5N and CEM III/A 42.5N) as well as crystalline admixtures and bacterial spores, both in powder form, and PCE-based superplasticizer are utilized to evaluate the changes in consistency and setting time. The dosage of healing agents is taken between 0 − 5% by weight of powders. To start, tests on paste level were executed. The results show that the addition of healing agents affects the water demand, the consistency and setting time of the pastes. The inclusion of crystalline admixtures increases the water demand, while a declined trend of setting time is observed. The gradual addition of bacteria up to 5% slightly changes the water demand, but a significant delay on the initial and final setting times was detected.
Reference of this article: Hermawan, H., Minne, P., Brac, E.G., Wiktor, V., Serna Ros, P., Gruyaert, E. (2023). Influence of Crystalline Admixtures and Bacteria on the Fresh Properties of Self-healing Concrete. 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. https://doi.org/10.1007/978-3-031-21735-7_50
Affiliations:
Harry Hermawan, Peter Minne and Elke Gruyaert: KU Leuven, Ghent Technology Campus, Department of Civil Engineering, Materials and Constructions, Gebroeders De Smetstraat 1, 9000 Ghent, Belgium
Enricomaria Gastaldo Brac: Penetron Italia, 10093, Collegno, Italy
Virginie Wiktor: Cugla B.V., R&D center, Rudonk 6b, 4824 AJ Breda, the Netherlands
Pedro Serna: Instituto de Ciencia y Tecnología Del Hormigón (ICITECH), Universitat Politècnica de València, Camino de Vera S/n, 46022, Valencia, Spain
The full article can be found here: https://doi.org/10.1007/978-3-031-21735-7_50
Assessment of Sustainability and Self-Healing Performances of Recycled Ultra-High-Performance Concrete
Niranjan Prabhu Kannikachalam, Davide di Summa, Ruben P Borg, Estefaia Cueca Asensio, Matteo Parpanesi, Nele De Belie and Liberato Ferrara
Abstract: This research focuses on the evaluation of the sustainability of recycled ultra-high-performance concrete (R-UHPC) in a life cycle analysis (LCA) perspective, and with reference to a case study example dealing with structures exposed to extremely aggressive environments. This involves the assessment of the self-healing capacity of R-UHPC, as guaranteed by the R-UHPC aggregates themselves. Recycled aggregates (RA) were created by crushing 4-month-old UHPC specimens with an average compressive strength of 150 MPa. Different fractions of recycled aggregates (0 to 2 mm) and two different percentages (50 and 100%) were used as a substitute for natural aggregates in the production of R-UHPC. Notched beam specimens were pre-cracked to 150 μm using a three-point flexural test. The autogenous self-healing potential of R-UHPC, stimulated by the addition of a crystalline admixture, was explored using water absorption tests and microscopic crack healing at a pre-determined time (0 days, 1 month, 3 months, and 6 months) following pre-cracking. Continuous wet/ dry healing conditions were maintained throughout the experimental campaign. The specimens using R-UHPC aggregates demonstrated improved self-healing properties to those containing natural aggregates, especially from the second to the sixth month. To address the potential environmental benefits of this novel material in comparison to the conventional ones, an LCA analysis was conducted adopting the 10 CML-IA baseline impact categories, together with a life cycle cost (LCC) analysis to determine the related economic viability. Both LCA and LCC methodologies are integrated into a holistic design approach to address not only the sustainability concerns but also to promote the spread of innovative solutions for the concrete construction industry. As a case study unit, a basin for collection and cooling of geothermal waters was selected. This is representative of both the possibility offered, in terms of structural design optimization and reduction of resource consumption, and of reduced maintenance guaranteed by the retained mechanical performance and durability realized by the self-healing capacity of R-UHPC.
Reference of this article: Niranjan Prabhu Kannikachalam, Davide di Summa, Ruben P Borg, Estefaia Cueca Asensio, Matteo Parpanesi, Nele De Belie and Liberato Ferrara, Assessment of Sustainability and Self-Healing Performances of Recycled Ultra-High-Performance Concrete, ACI Materials Journal, V. 120, No. 1, January 2023, DOI:10.14359/51737336.
Affiliations:
Niranjan Prabhu Kannikachalam, Ruben P Borg, Estefaia Cueca Asensio, Matteo Parpanesi, and Liberato Ferrara: Politecnico di Milano, Department of Civil and Environmental Engineering, piazza Leonardo da Vinci 32, 20133 Milan, Italy
Davide Di Summa, 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
The full article can be found here: https://www.concrete.org/publications/internationalconcreteabstractsportal.aspx?m=details&i=51737336
Fatigue behavior and effect of stimulated autogenous self-healing in Ultra High-Performance Concrete
Niranjan Prabhu Kannikachalam, David Alejandro Clerque Vela, Yanira Ginori Ocampo Pacheco, Francesco Lo Monte, Nele De Belie Liberato Ferrara & Liberato Ferrara
Abstract: This paper investigates the mechanical response under fatigue cycles in Ultra-High-Performance Con- crete (UHPC) under four-point flexural loading, focusing on the effect of damage recovery triggered by stimulated autogenous self-healing. Thin beam specimens were pre-cracked up to 0.25 mm residual crack opening displacement under monotonic loading and then subjected to cyclic loading with a fre- quency of 5.5 Hz and a load amplitude equal to 10-80% of the load corresponding to the load at residual pre-crack width. Cyclic loading was applied for 700,000 cycles or up to the attainment of 1 mm total crack opening displacement at maximum load, whichever was reached first. Specimens were then healed underwater, and the fatigue tests were repeated to failure after the scheduled healing period of 1, 3, or 6 months. Self-healing performance was assessed via ultrasonic pulse velocity test and micro- scopic image analysis. Furthermore, the effects of self-healing in fatigue-crack growth rate, stiffness degradation, and critical crack opening were identified together with the benefits brought in as residual fatigue life recovery. The three-month healed specimens showed up to twenty times reduction in the rate of crack opening displacement as compared to the same specimen before the healing period.
Reference of this article: Niranjan Prabhu Kannikachalam, David Alejandro Clerque Vela, Yanira Ginori Ocampo Pacheco, Francesco Lo Monte, Nele De Belie Liberato Ferrara & Liberato Ferrara Proc. of the 14th fib International PhD Symposium in Civil Engineering Sep. 5 to 7, 2022, Rome, Italy, pages 297-304 ISBN: 978-2-940643-17-2
Affiliations:
Niranjan Prabhu Kannikachalam, David Alejandro Clerque Vela, Yanira Ginori Ocampo Pacheco, Francesco Lo Monte and Liberato Ferrara: Department of Civil and Environmental Engineering, Politecnico di Milano, Milan, Italy
Niranjan Prabhu Kannikachalam and Nele De Belie: Magnel-Vandepitte Laboratory, Department of Structural Engineering and Building Materials, Faculty of Engineering and Architecture,
Ghent University, Ghent, Belgium
The full article can be found here: https://www.fib-international.org/publications/fib-proceedings/14th-phd-symposium-in-rome-italy-2022-proceedings pages 297-304
Chapter 8: Contextualizing technology transfer: a review of university-industry transfer in the construction industry
Laís Bandeira Barros , Mirjam Knockaert & Laura Lecluyse
Abstract: In this chapter, we take a business-related contextual perspective into the technology transfer literature, and focus specifically on understanding what we know and what is still to be explored in terms of technology transfer in the construction industry. We take the construction industry as a representing an interesting setting for a review with a contextual dimension for several reasons, like, at least in Europe, the construction industry has often been considered a mature, traditional industry, often conservative and attached to familiar technology, but heavily challenged by an increased global competition, urging the firms in this industry to engage in innovation. Furthermore, next to synthesizing current knowledge, and contrasting it to the tech transfer literature in general, this chapter also presents a research agenda for future research into this intriguing field.
Reference of this article:Bandeira Barros, L., Knockaert, M., & Lecluyse, L. (2022). "Chapter 8: Contextualizing technology transfer: a review of university-industry transfer in the construction industry". In Handbook of Technology Transfer. Cheltenham, UK: Edward Elgar Publishing. Retrieved May 8, 2023
Affiliations:
The full article can be found here: https://doi.org/10.4337/9781800374409.00016