scholarly journals Application of bacteria in concrete: a critical evaluation of the current status

2016 ◽  
Vol 1 ◽  
pp. 56 ◽  
Author(s):  
Nele De Belie
Keyword(s):  
Concrete Strength ◽  
Critical Evaluation ◽  
Current Status ◽  
Carbonate Precipitation ◽  
Self Healing ◽  
Calcium Carbonate Precipitation ◽  
Healing Efficiency ◽  
New Strategy ◽  
Concrete Elements ◽  
Urea Decomposition

Microbially induced carbonate precipitation has been tested over more than a decade as a technique to enhance concrete properties. Mainly bacteria following the pathways of urea decomposition, oxidation of organic acids, or nitrate reduction have been studied for this purpose. For bacteria mixed into fresh concrete, it is difficult to prove that they actively contribute to calcium carbonate precipitation and the effects on concrete strength are variable. Application of bacteria for surface consolidation has been shown to reduce water absorption and increase durability. Microbial self-healing of cracks in concrete shows promising results at the laboratory scale. Especially the use of self-protected mixed cultures opens perspectives for practical application. However, their self-healing efficiency needs to be further proven in larger concrete elements, and under non-ideal conditions. The use of denitrifying cultures for concurrent self-healing and production of corrosion inhibiting nitrites is a promising new strategy.

scholarly journals Self-Healing of Concrete Cracks by Ceramsite-Loaded Microorganisms

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Jing Xu ◽  
Xianzhi Wang ◽  
Junqing Zuo ◽  
Xiaoyan Liu
Keyword(s):  
Heat Treatment ◽  
Compressive Strength ◽  
Heating Temperature ◽  
Concrete Strength ◽  
The Self ◽  
Self Healing ◽  
Healing Efficiency ◽  
Maximum Crack ◽  
Harsh Conditions ◽  
Urea Decomposition

Protective carrier is essential for the self-healing of concrete cracks by microbially induced CaCO3 precipitation, owing to the harsh conditions in concrete. In this paper, porous ceramsite particles are used as microbial carrier. Heat treatment and NaOH soaking are first employed to improve the loading content of the ceramsite. The viability of bacterial spores is assessed by urea decomposition measurements. Then, the self-healing efficiency of concrete cracks by spores is evaluated by a series of tests including compressive strength regain, water uptake, and visual inspection of cracks. Results indicate that heat treatment can improve the loading content of ceramsite while not leading to a reduction of concrete strength by the ceramsite addition. The optimal heating temperature is 750°C. Ceramsite particles act as a shelter and protect spores from high-pH environment in concrete. When nutrients and spores are incorporated in ceramsite particles at the same time, nutrients are well accessible to the cells. The regain ratio of the compressive strength increases over 20%, and the water absorption ratio decreases about 30% compared with the control. The healing ratio of cracks reaches 86%, and the maximum crack width healed is near 0.3 mm.

Soluble Silicates as Additives for Self-Sealing and Self-Healing Concrete

2016 ◽  
Vol 1813 ◽  
Author(s):  
L. E. Rendon Diaz Miron ◽  
M. E. Lara Magaña
Keyword(s):  
Mechanical Properties ◽  
Crack Formation ◽  
Healing Process ◽  
Self Healing ◽  
Reaction Products ◽  
Calcium Carbonate Precipitation ◽  
Broad Perspective ◽  
Healing Efficiency ◽  
Tensile Forces ◽  
Solubility Ratio

ABSTRACTTensile strength of concrete is limited and therefore is sensitive to crack formation. Steel reinforcement is added to bear the tensile forces; nonetheless, this does not completely omit crack formation. Repair of cracks in concrete is time-consuming and expensive. Self-sealing and self-healing of cracks upon appearance would therefore be a convenient property. We propose a mechanism to obtain self-repair of the concrete by adding soluble silicates (ASS) which will induce a self-sealing and self-healing process catalyzed by natural periods of wet and dry states of the concrete. Self-sealing approaches prevent the ingress of harsh chemical substances which may deteriorate the concrete matrix. This can be achieved by self-healing of concrete cracks (e.g. further cement hydration, calcium carbonate precipitation) and autonomous healing (e.g. further hydration of partially soluble silicates added as healing agents). The autogenous healing efficiency depends on the amount of deposited reaction products (ASS), its solubility (ratio of calcium to sodium silicate), the availability of water, and the crack width (restricted by adding microfibers). The self-sealing efficiency is generally evaluated by measuring the decrease in water permeability and air flow through the crack. The healing efficiency is usually evaluated by testing concrete´s regain in mechanical properties after crack formation; by reloading the cracked and autonomously healed specimen and comparing the obtained mechanical properties with the original ones. Self-sealing and self-healing of concrete gives a broad perspective and new possibilities to make future concrete structures more durable.

Application of Bacteria as Self-Healing Agent for the Concrete and Microscopic Analysis of the Microbial Calcium Precipitation Process

2020 ◽  
Vol 846 ◽  
pp. 237-242
Author(s):  
Zdeněk Prošek ◽  
Pavla Ryparová ◽  
Pavel Tesárek
Keyword(s):  
Culture Media ◽  
Microscopic Analysis ◽  
Precipitation Process ◽  
Carbonate Precipitation ◽  
Self Healing ◽  
Calcium Carbonate Precipitation ◽  
Cement Pastes ◽  
X Ray ◽  
Healing Agent ◽  
Calcium Precipitation

Cracks affect the durability of concrete by increasing its permeability. Self-healing materials can begin repairing themselves immediately after creating a crack. This is a big advantage of self-healing materials. In this study, effect of self-healing agents based on calcium carbonate precipitation for concrete is monitored for three months. Bacillus pseudofirmus was chosen as a self-healing agent and was tested on old cement pastes. Calcium precipitation was analyzed by scanning electron microscope with Energy-dispersive X-ray spectroscopy. The effect of added spontaneous calcination, culture media, bacteria and Ca2+ was monitored.

Determination of Micromechanical Properties of Cementitious Materials with Self-Healing Agent

2021 ◽  
Vol 880 ◽  
pp. 149-154
Author(s):  
Zdeněk Prošek ◽  
Pavla Ryparová ◽  
Aleš Jíra ◽  
Petr Bílý ◽  
Pavel Tesárek
Keyword(s):  
Culture Medium ◽  
Cementitious Materials ◽  
Carbonate Precipitation ◽  
Self Healing ◽  
Calcium Carbonate Precipitation ◽  
Spontaneous Crystallization ◽  
Agent Based ◽  
Micromechanical Properties ◽  
Healing Agent

The paper deals with the determination of nano, microstructural, and micromechanical properties of cementitious materials surface with self-healing agent based on calcium carbonate precipitation (calcite). This was done by means of electron microscopy with elemental microanalysis and nanoindentation. These methods can define parameters of individual phases within cementitious materials, which are important for the development of micromechanical models. Bacillus pseudofirmus in combination with culture medium 235 was chosen as a self-healing agent. Our study provides information about micromechanical properties of crystals resulting from spontaneous crystallization from the culture medium and from crystallization caused by bacteria.

scholarly journals Potential of fungi to produce bioconcrete

2020 ◽  
Vol 5 ◽  
pp. 157-162
Author(s):  
Carolina Martuscelli ◽  
Célia Soares ◽  
Nelson Lima ◽  
Aires Camões
Keyword(s):  
Electron Microscopy ◽  
Penicillium Chrysogenum ◽  
Chemical Constituents ◽  
Carbonate Precipitation ◽  
Self Healing ◽  
Calcium Carbonate Precipitation ◽  
Sustainable Solutions ◽  
Induction Process ◽  
Potential Use ◽  
Scanning Electron

The cracks in concrete reduce their resistance capacity and allow the entry of harmful agents both for their microstructure and for the reinforcements located inside the structure. Several studies have been done to promote sustainable solutions for this problem. The microbiologically induced calcium carbonate precipitation (MICCP) is an alternative to traditionally used methods and a way to reduce the environmental impact of using more cement and polymers. Most of the biocementation studies to fill cracks or to promote bio self-healing on concrete present bacteria as the microorganisms responsible for the CaCO3 induction process. Fungi are potentially better for the biocementation process because they have more biomass and some develop filaments that can be used as microfibers on materials. Thus, the present work proposes the development of a methodology to analyse the potential use of two urease-positive fungi (Penicillium chrysogenum MUM 9743 and Neurospora crassa MUM 9208) to produce bioconcrete. The microstructure and chemical constituents of biocrystals formed due to MICCP were observed under Scanning Electron Microscopy (SEM). SEM showed fungal mycelia as bio-based fiber in bioconcrete and clusters of probable calcite crystals on and around mycelia. Both fungi were able to promote biocimentation of sand.

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