Bio-reinforced self-healing concrete using magnetic iron oxide nanoparticles
- Authors: Seifan, Mostafa , Sarmah, Ajit , Ebrahiminezhad, Alireza , Ghasemi, Younes , Samani, Ali Khajeh , Berenjian, Aydin
- Date: 2018
- Type: Text , Journal article
- Relation: Applied Microbiology and Biotechnology Vol. 102, no. 5 (2018), p. 2167-2178
- Full Text: false
- Reviewed:
- Description: Immobilization has been reported as an efficient technique to address the bacterial vulnerability for application in bio self-healing concrete. In this study, for the first time, magnetic iron oxide nanoparticles (IONs) are being practically employed as the protective vehicle for bacteria to evaluate the self-healing performance in concrete environment. Magnetic IONs were successfully synthesized and characterized using different techniques. The scanning electron microscope (SEM) images show the efficient adsorption of nanoparticles to the Bacillus cells. Microscopic observation illustrates that the incorporation of the immobilized bacteria in the concrete matrix resulted in a significant crack healing behavior, while the control specimen had no healing characteristics. Analysis of bio-precipitates revealed that the induced minerals in the cracks were calcium carbonate. The effect of magnetic immobilized cells on the concrete water absorption showed that the concrete specimens supplemented with decorated bacteria with IONs had a higher resistance to water penetration. The initial and secondary water absorption rates in bio-concrete specimens were 26% and 22% lower than the control specimens. Due to the compatible behavior of IONs with the concrete compositions, the results of this study proved the potential application of IONs for developing a new generation of bio self-healing concrete.
Mechanical properties of bio self-healing concrete containing immobilized bacteria with iron oxide nanoparticles
- Authors: Seifan, Mostafa , Sarmah, Ajit , Samani, Ali Khajeh , Ebrahiminezhad, Alireza , Ghasemi, Younes , Berenjian, Aydin
- Date: 2018
- Type: Text , Journal article
- Relation: Applied Microbiology and Biotechnology Vol. 102, no. 10 (2018), p. 4489-4498
- Full Text: false
- Reviewed:
- Description: Concrete is arguably one of the most important and widely used materials in the world, responsible for the majority of the industrial revolution due to its unique properties. However, it is susceptible to cracking under internal and external stresses. The generated cracks result in a significant reduction in the concrete lifespan and an increase in maintenance and repair costs. In recent years, the implementation of bacterial-based healing agent in the concrete matrix has emerged as one of the most promising approaches to address the concrete cracking issue. However, the bacterial cells need to be protected from the high pH content of concrete as well as the exerted shear forces during preparation and hardening stages. To address these issues, we propose the magnetic immobilization of bacteria with iron oxide nanoparticles (IONs). In the present study, the effect of the designed bio-agent on mechanical properties of concrete (compressive strength and drying shrinkage) is investigated. The results indicate that the addition of immobilized Bacillus species with IONs in concrete matrix contributes to increasing the compressive strength. Moreover, the precipitates in the bio-concrete specimen were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The characterization studies confirm that the precipitated crystals in bio-concrete specimen were CaCO3, while no precipitation was observed in the control sample.
The role of magnetic iron oxide nanoparticles in the bacterially induced calcium carbonate precipitation
- Authors: Seifan, Mostafa , Ebrahiminezhad, Alireza , Ghasemi, Younes , Samani, Ali Khajeh , Berenjian, Aydin
- Date: 2018
- Type: Text , Journal article
- Relation: Applied Microbiology and Biotechnology Vol. 102, no. 8 (2018), p. 3595-3606
- Full Text: false
- Reviewed:
- Description: Recently, magnetic iron oxide nanoparticles (IONs) have been used to control and modify the characteristics of concrete and mortar. Concrete is one of the most used materials in the world; however, it is susceptible to cracking. Over recent years, a sustainable biotechnological approach has emerged as an alternative approach to conventional techniques to heal the concrete cracks by the incorporation of bacterial cells and nutrients into the concrete matrix. Once cracking occurs, CaCO3 is induced and the crack is healed. Considering the positive effects of IONs on the concrete properties, the effect of these nanoparticles on bacterial growth and CaCO3 biosynthesis needs to be evaluated for their possible application in bio self-healing concrete. In the present work, IONs were successfully synthesized and characterized using various techniques. The presence of IONs showed a significant effect on both bacterial growth and CaCO3 precipitation. The highest bacterial growth was observed in the presence of 150 μg/mL IONs. The highest concentration of induced CaCO3 (34.54 g/L) was achieved when the bacterial cells were immobilized with 300 μg/mL of IONs. This study provides new data and supports the possibility of using IONs as a new tool in designing the next generation of bio self-healing concrete.