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Factors Affecting Concrete Self-Healing Performance
Published in Ghasan Fahim Huseien, Iman Faridmehr, Mohammad Hajmohammadian Baghban, Self-Healing Cementitious Materials, 2022
Ghasan Fahim Huseien, Iman Faridmehr, Mohammad Hajmohammadian Baghban
Self-healing concrete is the name given to concrete that contains autonomous healing substances that enter crack formations and heal them without any manual human intervention. Autonomous healing is most frequently achieved by mixing concrete with fibers, crystalline admixtures, bacteria, polymers, and other such materials. Normally, chemical reactions and the presence of water make up the autonomous healing procedure that assesses natural healing mechanisms. The strength of the concrete is enhanced followed the diminished width of a given crack via the mentioned autonomous healing procedure. Contrastingly, Figure 8.1 portrays the autonomous procedures involved in artificial autonomous healing. The efficacy of self-healing is enhanced via immobilization, vascular, or encapsulation techniques that incorporate healing agents into the concrete.
Sustainability of Ceramic Waste in the Concrete Industry
Published in Kwok Wei Shah, Ghasan Fahim Huseien, Recycled Ceramics in Sustainable Concrete, 2020
Kwok Wei Shah, Ghasan Fahim Huseien
During the past decade, the self-healing technique had been extensively studied and introduced as an innovative technique for concrete crack self-repair. However, several innovative strategies to self-healing for cementitious materials have been proposed and developed. Nowadays, it is known as the life cycle assessment (LCA) methodology, which has been standardized in ISO 14040-14044. Thus far, it has been used for assessing the environmental impact of all kinds of products and services preferably from cradle to grave. The goal of this LCA was a quantification of the environmental impact reduction that could be achieved by using the proposed self-healing concrete instead of a more traditional concrete. Some direct benefits of self-healing concrete include the reduction of the rate of deterioration, extension of service life, and reduction of repair frequency and cost over the life cycle of a concrete infrastructure. These direct benefits may be expected to lead to enhanced environmental sustainability since fewer repairs implies lower rate of material resource usage and reduction in energy consumption and pollutant emission in material production and transport, as well as that associated with traffic alterations in transportation infrastructure during repairs/reconstruction [11]. Van Belleghem et al. [12] reported that the self-healing of cracks with encapsulated polyurethane precursor formed a partial barrier against immediate ingress of chlorides through the cracks. Application of self-healing concrete was able to reduce the chloride concentration in a cracked zone by 75% or more. Service life of self-healing concrete in marine environments could amount to 60–94 years as opposed to only 7 years for ordinary (cracked) concrete. However, life cycle assessment calculations indicated important environmental benefits (56–75%) and achievable service life extension.
Engineering application of microbial self-healing concrete in lock channel wall
Published in Marine Georesources & Geotechnology, 2022
Concrete is the most widely used construction material in the world (Su et al. 2017). However, due to the brittleness and low tensile strength of concrete, the occurrence of cracking is inevitable (Jang, Kim, and Oh 2011), which provides an intrusion channel for corrosive ions (Yang, He et al. 2016). Cracking leads to a significant reduction in the durability of the concrete (Wiktor and Jonkers 2011), a shortened service life, and even a catastrophic accident. Traditional repair methods, such as grouting replacement and caulking plugging are passive repair afterwards, which are difficult, costly and ineffective (Van Tittelboom et al. 2010). An effective way (Pungrasmi et al. 2019) to solve this problem is to compound the self-healing agents into the concrete matrix to make the concrete cracks a self-healing function (De Belie and De Muynck 2009; Seifan, Samani, and Berenjian 2016). Microbial self-healing technology uses microbial metabolism to produce relatively insoluble compounds (Song and Elsworth 2020), such as calcium carbonate, to achieve self-healing of concrete, which shows a good prospect of development and commercial application among those self-healing technologies (Wiktor and Jonkers 2016). Compared with normal concrete, the self-healing concrete has a longer service life and a significant reduction in maintenance costs (Tziviloglou et al. 2016; Ling and Qian 2017).
Evaluation of self-healing performance of concrete containing fly ash and fibres
Published in Australian Journal of Structural Engineering, 2021
Seyedehtina Sajjadi, Rahmat Madandoust
Since the costs involved for maintenance and repair of concrete structures are usually high, researchers are focusing on the development of self-healing concrete to increase the service life and hence to minimise the maintenance costs. The phenomenon of self-healing of concrete has been known for many years. In 1836, the ability of concrete in self-healing of its small cracks in the presence of water was observed by the French Academy of Sciences (Hearn 1998). After that, several studies were conducted on self-healing (Glanville 1926; Hearn and Morley 1997; Hyde and Smith 1889; Neville 2002; Edvardsen 1999). Almost all researchers agreed that the main reason for self-healing in concrete at early ages was hydration of unhydrated cementitious components, and in older concrete, the formation of calcium carbonate was the cause of self-healing (Neville 2002).
Review of the potential application of bacteria in self-healing and the improving properties of concrete/mortar
Published in Journal of Sustainable Cement-Based Materials, 2021
Parya Dinarvand, Alireza Rashno
Self-healing concrete is referred to as a concrete that can heal its small cracks automatically and without human help [80]. The various self-healing methods in materials, based on the latest investigations in this area, are shown briefly in Figure 5 [81-96]. Different mechanisms of natural self-healing are shown in Figure 5. The base of the natural self-healing is the hydration of the cement elements in concrete and the formation of calcium carbonate. In many cases, some mechanisms can happen simultaneously to heal the crack. This method is useful to prevent the development of cracks, and it can heal the cracks with 0.1–0.2 mm width [28]. Among these mechanisms, the most effective methods for healing the cracks is the formation of calcium carbonate and calcium hydroxide. The basic mechanisms for the formation of calcium carbonate and calcium hydroxide are mentioned in Equations (18)–(20). Carbon dioxide is dissolved in water. Because of cement hydration, calcium ion is released and spreads on the crack surface and reacts with and therefore, calcium carbonate crystals are produced [7]