Chloride Transport Characterisation in Self-healing Concretes
Kiran Dabral, Esteban Camacho, Pedro Serna & Maria Cruz Alonso
Abstract: It is essential to evaluate the deterioration of concrete structures in a chloride-laden aggressive environment, which may lead to the corrosion of embedded reinforcement and eventually to the loss of the integrity of the concrete structure. Several tests are available in the literature that evaluates the ingress of deleterious chemical species into the concrete matrix, but an uncracked state of concrete is largely considered in these tests. This work demonstrates the testing of concrete samples from full-scale beam elements, the introduction of cracking imitating the realistic crack specifications, and analysis for service life evaluation for cracked concretes. The autogenous property of crack healing in concrete is amplified by the addition of self-healing agents – crystalline admixture and bacteria. This study highlights that the presence of cracks in concrete significantly influences the chloride ingress profile. Two-fold diffusion of ions occurs – one perpendicular to the exposed surface and the other perpendicular to the crack walls. It is reported that the cracked and uncracked migration coefficients through and across the crack are highly affected by its existence, not necessarily controlled by the crack width at the surface. Consequently, the service life evaluation for a cracked concrete element needs to be adapted to account for the influence due to cracking.
Reference of this article: Dabral, K., Camacho, E., Serna, P., Alonso, M.C. (2024). Chloride Transport Characterisation in Self-healing Concretes. In: Banthia, N., Soleimani-Dashtaki, S., Mindess, S. (eds) Smart & Sustainable Infrastructure: Building a Greener Tomorrow. ISSSI 2023. RILEM Bookseries, vol 48. Springer, Cham.
Affiliations:
Kiran Dabral and Esteban Camacho: RDC Research and Development Concrete, 46055 València, Spain
Maria Cruz Alonso: Universitat Politècnica de València, 46022 València, Spain
Pedro Serna: Eduardo Torroja Institute of Construction Science (IETcc-CSIC), 28033 Madrid, Spain
Corresponding author:
The full article can be found here: https://doi.org/10.1007/978-3-031-53389-1_63
An analysis of the commercialisation barriers of self-healing concrete
Laís Bandeira Barros, Mirjam Knockaert, & José Roberto Tenório Filho
Abstract: Interest in more sustainable construction has grown in recent years. Evidence indicates that larger societal trends and the economic climate have an impact on the transfer of new technologies in the construction sector from university to industry. The transition to sustainability and concerns regarding climate change represent pressing issues to innovate in the sector. In order to decrease CO2 emissions from cement production, strategies have been developed to reduce the environmental burdens, such as the use of smart materials. The goal is to use more durable materials. Significant research has been performed into the development of self-healing technologies for concrete as a smart material. The advantages of self-healing concrete are many and can be significant to all stakeholders, including researchers, companies and end users. In spite of the progress made by past research, the commercialisation of self-healing concrete is still in its infancy. To fulfil this need, our study examines the commercialisation of self-healing concrete as a process complicated by divergent barriers. By carrying out semi-structured interviews with stakeholders, this study generates its contribution: the development of the self-healing concrete value chain identifying the commercialisation barriers as well as the analysis of these barriers that the innovation encounters along its value chain.
Reference of this article:An analysis of the commercialisation barriers of self-healing concrete Laís Bandeira Barros, Mirjam Knockaert and Roberto Tenório MATEC Web Conf., 378 (2023) 10001
Affiliations:
Laís Bandeira Barros and Mirjam Knockaert: Ghent University, Department of Marketing, Innovation and Organisation, Faculty of Economics and Business Administration, Tweekerkenstraat 2, Ghent 9000, Belgium
José Roberto Tenório Filho: Ghent University, Department of Structural Engineering and Building Materials, Technologiepark-Zwijnaarde 60, Ghent B-9052, Belgium
The full article can be found here: https://doi.org/10.1051/matecconf/202337810001
Autonomous healing by vascular networks: tracking of cracks interaction by Ultrasounds and Acoustic Emission
Eva Vangansbeke, Yasmina Shields, Nele De Belie, Kim Van Tittelboom & Eleni Tsangouri
Abstract: The tracking of healing on concrete slabs where dense crack patterns are formed under bending is reported using Acoustic Emission (AE) and Ultrasound Pulse Velocity (UPV). Additively manufactured polymeric networks are designed to distribute a polyurethane agent through capillary actions and under pressure to the open cracks, formed in the slabs. It is shown that the crack pattern is controlled by the geometry of the vascular networks that are positioned near the steel reinforcement. The activation of both conventional linear and interlinked web-shaped networks is monitored by AE, however in both cases the load at which the initial cracks form is lower in series with embedded networks compared to the reference series, an indication of an overall weakening effect. The area where the healing agent circulates is larger (300x400 mm2) than past tests on beams, but only local healing is evident by UPV mapping. An indirect proof of cracks filling with stiffened agent is provided by the AE pencil-lead breaking test, as the amplitude recovery after healing can be linked to crack closure. This preliminary work evaluates the design of 3D printed vascular networks, but also explores the potential of AE and UPV as inspection tools in healing studies.
Reference of this article:Autonomous healing by vascular networks: tracking of cracks interaction by Ultrasounds and Acoustic Emission Eva Vangansbeke, Yasmina Shields, Nele De Belie, Kim Van Tittelboom and Eleni Tsangouri MATEC Web Conf., 378 (2023) 04003
Affiliations:
Eva Vangansbeke and Eleni Tsangouri: Dept. Mechanics of Materials and Constructions (MeMC), Vrije Universiteit Brussel (VUB), Brussels, Belgium
Yasmina Shields, Nele De Belie and Kim Van Tittelboom: 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://doi.org/10.1051/matecconf/202337804003
Assessment of autonomous and autogenous healing on cementitious grouts promoted by additions of microcapsules and crystalline admixtures
Suelen da Rocha Gomes, Padmapryia A. Kumar, Sripriya Rengaraju, Abir Al-Tabbaa, Liberato Ferrara, Luis Sánchez and Mercedes Sánchez Moreno
Abstract: The demand for more sustainable building materials has led to the development of systems with self-repairing properties. The self-healing technology has been shown to be effective in concrete and mortars, however, this technology is not often studied in grouts. Cementitious systems can show an autogenous healing, i.e., an intrinsic ability to repair microcracks by themselves. This type of healing can be improved by the addition of crystalline admixtures. In addition, the crack healing can also be enhanced by adding other materials, e.g., through the incorporation of polymeric microcapsules into the cementitious matrix that will promote a healing effect but, in this case, an autonomous healing. Thus, the main objective of this work is to assess the effect of the addition of microcapsules and crystalline admixture on viscosity and water capillary absorption of cementitious grouts. Cementitious grouts (w/b = 0.46 and w/b = 0.39) were prepared containing microcapsules (3% by weight of binder) and crystalline admixture (3% by weight of binder). Rheological measurements and water sorptivity tests were made. Viscosity measurements were taken at 3, 20 and 60 minutes. Sorptivity tests were performed on cracked specimens in order to quantify the healing efficiency. Cracks were created 7 and 28 days after casting and the water absorption was measured for 7, 14 and 28 days after cracking. The results showed that the viscosity changed considerably depending on the w/b ratio and the healing agent type. Among all grouts, reference grout presented the highest viscosity and grout with microcapsules and crystalline admixture the lowest. The water absorption of the grouts with microcapsules was the lowest regardless of curing age and w/b ratio. Regarding crystalline admixture, at both curing ages the water absorption was quite high.
Reference of this article: Assessment of autonomous and autogenous healing on cementitious grouts promoted by additions of microcapsules and crystalline admixtures Suelen da Rocha Gomes, Padmapryia A. Kumar, Sripriya Rengaraju, Abir Al-Tabbaa, Liberato Ferrara, Luis Sánchez and Mercedes Sánchez Moreno MATEC Web Conf., 378 (2023) 07001
Affiliations:
Suelen da Rocha Gomes, Luis Sánchez, Mercedes Sánchez Moreno,: Department of Inorganic Chemistry and Chemical Engineering, Chemical Institute for Energy and Environment, IQUEMA. University of Córdoba, Córdoba, Spain
Padmapryia A. Kumar, Sripriya Rengaraju and Abir Al-Tabbaa: Department of Engineering, Cambridge, UK
Liberato Ferrara: Department of Civil and Environmental Engineering, Politecnico di Milano, Milan, Italy
The full article can be found here: https://doi.org/10.1051/matecconf/202337807001
Assessment of impact resistance recovery in Ultra High-Performance Concrete through stimulated autogenous self-healing in various healing environments
Niranjan Prabhu Kannikachalam, Paula Sofia Marin Peralta, Didier Snoeck, Nele De Belie and Liberato Ferrara
Abstract: Ultra High-Performance Concrete (UHPC) is widely acknowledged for its remarkable mechanical properties, owing to its compact microstructure. The response of UHPC to impact forces plays a vital role in ensuring the safety and longevity of structures, specifically in protective buildings, high-performance pavements and offshore concrete structures. In this context, this paper reports on an experimental investigation aimed at assessing the effects of stimulated autogenous self-healing of UHPC on the recovery of its performance under impact loadings. Drop weight tests were performed on UHPC slabs, with a 10 kg heavy impactor dropped from the height of 1 m on the centre of the specimens. Specimens were pre-cracked by repeated impacts up to 40% of their predetermined capacity. Pre-cracked specimens were exposed to different healing conditions, water submersion, 95% ± 5% RH, and wet/dry cycling (12/12 h) either in water or in a NaCl solution. Self-healing was evaluated through rebound height, elastic stiffness recovery, natural frequency, and laser displacement measurements. High-speed cameras and Digital Image Correlation were used to capture rebound height and crack formation. Performance was assessed at time 0, pre-damaging, 1, 2, and 4 months. After the healing period, all specimens were tested to failure. Specimens exhibited an increasing healing efficiency when moving from 95% ± 5% RH, over wet/dry cycling, to submerged conditions. Specimens healed continuously under submerged conditions exhibited a complete closure of surface cracks (50–150 μm) and an 80% recovery in natural frequency. Furthermore, they showed a more than 10% increase in stiffness and energy dissipation capacity after four months of healing.
Reference of this article:Niranjan Prabhu Kannikachalam, Paula Sofia Marin Peralta, Didier Snoeck, Nele De Belie, Liberato Ferrara, Assessment of impact resistance recovery in Ultra High-Performance Concrete through stimulated autogenous self-healing in various healing environments, Cement and Concrete Composites, Volume 143, 2023, 105239, ISSN 0958-9465,
Affiliations:
Niranjan Prabhu Kannikachalam, Paula Sofia Marin Peralta and Liberato Ferrara: Politecnico di Milano, Department of Civil and Environmental Engineering, piazza Leonardo da Vinci 32, 20133 Milan, Italy
Niranjan Prabhu Kannikachalam 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
Didier Snoeck: Building, Architecture and Town Planning (BATir) Department, Université Libre de Bruxelles, Belgium
The full article can be found here: https://doi.org/10.1016/j.cemconcomp.2023.105239