scholarly journals Self-Healing Concrete by Biological Substrate

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4099 ◽  
Author(s):  
How-Ji Chen ◽  
Ching-Fang Peng ◽  
Chao-Wei Tang ◽  
Yi-Tien Chen
Keyword(s):  
Calcium Carbonate ◽  
Lightweight Aggregate Concrete ◽  
White Crystal ◽  
Repair Material ◽  
Self Healing ◽  
Bacterial Strains ◽  
Calcium Carbonate Precipitation ◽  
Bacillus Pasteurii ◽  
Concrete Crack ◽  
Crack Repair

At present, the commonly used repair materials for concrete cracks mainly include epoxy systems and acrylic resins, which are all environmentally unfriendly materials, and the difference in drying shrinkage and thermal expansion often causes delamination or cracking between the original concrete matrix and the repair material. This study aimed to explore the feasibility of using microbial techniques to repair concrete cracks. The bacteria used were environmentally friendly Bacillus pasteurii. In particular, the use of lightweight aggregates as bacterial carriers in concrete can increase the chance of bacterial survival. Once the external environment meets the growth conditions of the bacteria, the vitality of the strain can be restored. Such a system can greatly improve the feasibility and success rate of bacterial mineralization in concrete. The test project included the microscopic testing of concrete crack repair, mainly to understand the crack repair effect of lightweight aggregate concrete with implanted bacterial strains, and an XRD test to confirm that the repair material was produced by the bacteria. The results show that the implanted bacterial strains can undergo Microbiologically Induced Calcium Carbonate Precipitation (MICP) and can effectively fill the cracks caused by external concrete forces by calcium carbonate deposition. According to the results on the crack profile and crack thickness, the calcium carbonate precipitate produced by the action of Bacillus pasteurii is formed by the interface between the aggregate and the cement paste, and it spreads over the entire fracture surface and then accumulates to a certain thickness to form a crack repairing effect. The analysis results of the XRD test also clearly confirm that the white crystal formed in the concrete crack is calcium carbonate. From the above test results, it is indeed feasible to use Bacillus pasteurii in the self-healing of concrete cracks.

Optimization of Calcium Carbonate Precipitation for Bacillus pasteurii

2012 ◽  
Vol 178-181 ◽  
pp. 676-679 ◽  
Author(s):  
Tao Duan ◽  
Wen Kun Zhu
Keyword(s):  
Calcium Carbonate ◽  
Crystal Formation ◽  
Carbonate Precipitation ◽  
X Ray Diffraction ◽  
Calcium Carbonate Precipitation ◽  
Electron Microscopic ◽  
Bacillus Pasteurii ◽  
Scanning Electron Microscopic ◽  
External Conditions ◽  
Effects Of Temperature

The effects of temperature, pH, precipitation time, reactant concentration, the crystal formation additive on the yield of calcium carbonate precipitation induced by bacillus pasteurii were investigated through orthogonal test. The morphology and structure of the calcium carbonate were characterized by scanning electron microscopic (SEM), Fourier transform infrared spectroscopy (IR) and powder X-ray diffraction (XRD). The results showed that the optimum conditions of calcium carbonate precipitation induced by bacillus pasteurii were temperature of 40oC, pH of 8, precipitation time of 3 d, Ca2+ of 1.5 mol/L, and Mg2+ of 0.05 mol/L. The crystal of calcium carbonate was calcites or mixture of calcites and vaterite. Its morphology and packing density were changed by different external conditions.

Effects of Various Sugars on the Mineralization of Microbiologically Induced Calcium Carbonate

2010 ◽  
Vol 152-153 ◽  
pp. 1669-1672
Author(s):  
Wen Kun Zhu ◽  
Xue Gang Luo
Keyword(s):  
Calcium Carbonate ◽  
Culture Medium ◽  
Precipitation Amount ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation ◽  
Bacillus Pasteurii

Sugar is one of the key nutrients required to microorganism growth. In this paper , the effects of various sugars on the mineralization of calcium carbonate induced by Bacillus pasteurii . The precipitation amount, forms and structures of calcium carbonate were characterized. The results indicated that the induced calcium carbonate precipitation are mainly calcite as irregular aggregated bodies and rhombus blocks and aragonite appeared when the culture medium was added with dextran. The calcium carbonate precipitation reached a maximum of 2.32 g when glucose was added into the culture.

scholarly journals Comparison of Microbially Induced Healing Solutions for Crack Repairs of Cement-Based Infrastructure

2021 ◽  
Vol 13 (8) ◽  
pp. 4287
Author(s):  
John Milan van der Bergh ◽  
Bojan Miljević ◽  
Snežana Vučetić ◽  
Olja Šovljanski ◽  
Siniša Markov ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Service Life ◽  
Cementitious Materials ◽  
Bacterial Suspension ◽  
Self Healing ◽  
Construction Costs ◽  
Recovery Processes ◽  
Concrete Crack ◽  
Crack Repair ◽  
Water Absorption Test

Reinforced concrete crack repair and maintenance costs are around 84% to 125% higher than construction costs, which emphasises the need to increase the infrastructure service life. Prolongation of the designed service life of concrete structures can have significant economic and ecological benefits by minimising the maintenance actions and related increase of carbon and energy expenditure, making it more sustainable. Different mechanisms such as diffusion, permeation and capillary action are responsible for the transport of fluids inside the concrete, which can impact on the structure service life. This paper presents data on microbially induced repair and self-healing solutions for cementitious materials available in the contemporary literature and compares results of compressive strength test and capillary water absorption test, which are relevant to their sealing and mechanical characteristics. The results of the repair and self-healing solutions (relative to unassisted recovery processes) were “normalized.” Externally applied bacteria-based solutions can improve the compressive strength of cementitious materials from 13% to 27%. The internal solution based solely on bacterial suspension had 19% improvement efficacy. Results also show that “hybrid” solutions, based on both bio-based and non-bio-based components, whether externally or internally applied, have the potential for best repair results, synergistically combining their benefits.

scholarly journals Research on the Preparation of Microbial Capsules by Epoxy Resin-Coated Bacillus pasteurii

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yingying Hu ◽  
Weitao Liu ◽  
Xinlei Jia ◽  
Lanjuan Xu ◽  
Jianjun Shen ◽  
...  
Keyword(s):  
Reaction Time ◽  
Epoxy Resin ◽  
High Efficiency ◽  
Water Inrush ◽  
Experimental Results ◽  
Wall Material ◽  
Self Healing ◽  
Calcium Carbonate Precipitation ◽  
Underground Engineering ◽  
Bacillus Pasteurii

With the increasing number of underground engineering construction projects such as coal mining, tunnel, and subway, water inrush disasters occur more and more frequently. Inspired by the phenomenon of microbial mineralization and diagenesis, microbial-induced calcium carbonate precipitation (MICP) is used to repair cracks in cement-based materials, which provides a new idea to solve the problem of water inrush. To investigate the self-healing properties of microbial capsules, this paper selected epoxy resin E-51 cured by DMP-30 as the wall material and Bacillus pasteurii as the core materials for experiments. In this paper, a single-factor method was adopted to determine the optimal preparation process of microbial capsules and the oil-phase separation method to prepare the microbial capsules. The effects of various factors on the experimental results under different core-wall ratios, reaction time, reaction temperatures, and agitation rates were analyzed. Microbial capsules were analyzed by Fourier transform infrared spectroscopy and optical microscopy to explore the functional groups and features of microbial capsules. The experimental results showed that the microbial capsules achieved the best performance with a core-to-wall ratio of 1 : 3, a reaction temperature of 50°C, a reaction time of 40 min, and a stirring rate of 300 rpm. Meanwhile, we determined the spore survival rate of microbial capsules and finally studied the waterproofness, storage stability, and rupture under the pressure of microbial capsules. We concluded that microbial capsules have high-efficiency and self-healing properties.

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