scholarly journals Bio-Engineered Concrete: A Critical Review on The Next Generation of Durable Concrete

2021 ◽  
Vol 7 (3) ◽  
pp. 335
Author(s):  
Md. Fahad Shahriar Zawad ◽  
Md. Asifur Rahman ◽  
Sudipto Nath Priyom
Keyword(s):  
Literature Review ◽  
Structural Engineering ◽  
Healing Process ◽  
Strength Properties ◽  
Historical Background ◽  
Self Healing ◽  
Mineralization Process ◽  
Infrastructural Development ◽  
Micro Cracks ◽  
Strength Increment

Concrete is a prerequisite material for infrastructural development, which is required to be sufficiently strong and durable. It consists of fine, coarse, and aggregate particles bonded with a fluid cement that hardens over time. However, micro cracks development in concrete is a significant threat to its durability. To overcome this issue, several treatments and maintenance methods are adopted after construction, to ensure the durability of the structure. These include the use of bio-engineered concrete, which involved the biochemical reaction of non-reacted limestone and a calcium-based nutrient with the help of bacteria. These bio-cultures (bacteria) act as spores, which have the ability to survive up to 200 years, as they are also found to start the mineralization process and the filling of cracks or pores when in contact with moisture. Previous research proved that bio-engineered concrete is a self-healing technology, which developed the mechanical strength properties of the composite materials. The mechanism and healing process of the concrete is also natural and eco-friendly. Therefore, this study aims to critically analyze bio-engineered concrete and its future potentials in the Structural Engineering field, through the use of literature review. The data analysis was conducted in order to provide gradual and informative ideas on the historical background, present situation, and main mechanism process of the materials. According to the literature review, bio-engineered concrete has a promising outcome in the case of strength increment and crack healing. However, the only disadvantage was its less application in the practical fields. The results concluded that bio-engineered concrete is a new method for ensuring sustainable infrastructural development. And also, it indicated that more practical outcome-based analysis with extensive application in various aspects should be conducted, in order to assess the overall durability.

Bio-inspired self-healing cementitious mortar using Bacillus subtilis immobilized on nano-/micro-additives

2018 ◽  
Vol 30 (1) ◽  
pp. 3-15 ◽  
Author(s):  
Rao Arsalan Khushnood ◽  
Siraj ud din ◽  
Nafeesa Shaheen ◽  
Sajjad Ahmad ◽  
Filza Zarrar
Keyword(s):  
Compressive Strength ◽  
Bacillus Subtilis ◽  
Iron Oxide ◽  
Cement Mortar ◽  
Healing Process ◽  
Main Concern ◽  
Scanning Electron Micrographs ◽  
Self Healing ◽  
Micro Cracks ◽  
Cracked Specimens

Bio-inspired self-healing strategies are much innovative and potentially viable for the production of healable cement mortar matrix. The present research explores the feasibility of gram-positive “Bacillus subtilis” microorganisms in the effective healing of nano-/micro-scale-induced structural and non-structural cracks. The main concern related to the survival of such microorganisms in cementitious environment has been successfully addressed by devising proficient immobilization scheme coherently. The investigated immobilizing media includes iron oxide nano-sized particles, micro-sized limestone particles, and milli-sized siliceous sand. The effect of induced B. subtilis microorganisms immobilized on nano-micro-additives was analyzed by the quantification of average compressive resistance of specimens (ASTM C109) and healing evaluation. The healing process was mechanically gauged by compressive strength regain of pre-cracked specimens after the healing period of 28 days. The pre-cracking load was affixed at 80% of ultimate compressive stress “[Formula: see text]” while the age of pre-cracking was kept variable as 3, 7, 14, and 28 days to precisely correlate healing effectiveness as the function of cracking period. The healing mechanism was further explored by examining the healed micro-crack using field emission scanning electron micrographs, energy dispersive x-ray spectrographs, and thermogravimetry. The results revealed that B. subtilis microorganisms contribute extremely well in the improvement of compressive strength and efficient healing process of pre-cracked cement mortar formulations. The iron oxide nano-sized particles were found to be the most effective immobilizer for preserving B. subtilis microbes till the generation of cracks followed by siliceous sand and limestone particles. The micro-graphical and chemical investigations endorsed the mechanical measurements by evidencing calcite precipitation in the induced nano-/micro-cracks as a result of microbial activity.

Effects of Programming Temperature on the Efficiency of Self-Healing Polymers

2012 ◽  
Author(s):  
Yves Quentin Yougoubare ◽  
Ifeanyi Janarus Okoro ◽  
Su-Seng Pang
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Recovery ◽  
Strength Properties ◽  
Self Healing ◽  
Test Results ◽  
Crack Healing ◽  
Micro Cracks ◽  
Intrinsic Correlation

Self-healing shape memory polymers possess the ability to heal macro and micro cracks by autonomic processes or when subjected to a suitable external stimulus. Recent advancements in the field have shown that the healing capabilities of self-healing polymers can be improved, thus yielding to high healing efficiencies. Depending on the application, the efficiency may refer to shape fixity, shape recovery ratio, dimensions recovery, strength regain, crack healing, etc. Based on test results, it is established that there is an intrinsic correlation between pre-strain levels, shape fixing and free shape recovery of samples programmed above the glass transition temperature (Tg). For samples programmed at multiple temperatures (above and below the glass transition temperature), the absence of lateral and 3D confinements lead to poor to no crack healing. Better compressive strength properties were, however, achieved by samples programmed at higher temperatures above Tg.

scholarly journals Study on Behaviour of Self-Healing Concrete Using Silica gel

2018 ◽  
Vol 7 (2.12) ◽  
pp. 411
Author(s):  
V Sumitha ◽  
P T. Ravichandran ◽  
Divya Krishnan K
Keyword(s):  
Compressive Strength ◽  
Mechanical Strength ◽  
Silica Gel ◽  
Blended Cement ◽  
Strength Properties ◽  
Self Healing ◽  
Split Tensile Strength ◽  
Sequence Of Events ◽  
Micro Cracks ◽  
Healing Agent

The procedures to enhance the strength and reliability of materials depend on the worldview of damage prevention, i.e. the materials are composed and arranged so that the development and expansion of damage is postponed however much as could reasonably be expected. The reinforced concrete structures are subjected to various loads such as heavy vehicles movement, earthquakes, and strong winds etc. which inevitably develop micro cracks. When micro cracks originates, a sequence of events begin within structures. These cracks affect the performance and strength of the structure, in addition withdurability of the structure.To overcome the above problems, it is required to consider the use the Self-Healing Concrete (SHC). In this work the attempt is made to study the use of silica gel as self-healing agent in M60 grade of concrete. The healing agent is mixed in varying proportions are 0.1%, 0.2%, 0.3% and 0.4% respectively by weight of cement inblended concrete mix grade of M60. The performance of silica gel as a self-healing agent was analyzed at different curing periods of 7, 14 and 28days. The concrete specimens were prepared to study the mechanical strength properties lie compressive strength, split tensile strength and flexural strength of blended concrete with and with addition of silica gel.The compressive strength of the blended cement concrete with addition of 0.3 % of silica gel gives 6.54% more strength compare to the control specimens at the age of 28 days testing. The performance of the 0.3% of Silica gel replacement in mechanical strength properties gives considerable effective enhancer compare to the control specimens. Based on the results it can be concluded that the optimum replacement is 0.3% silica gel. Silica gel can be used as one of the healing material in the construction of tunnel, underwater structures etc..  

scholarly journals Smart Self-Healing Capability of Asphalt Material Using Bionic Microvascular Containing Oily Rejuvenator

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6431
Author(s):  
Peng Yang ◽  
Li-Qing Wang ◽  
Xu Gao ◽  
Sai Wang ◽  
Jun-Feng Su
Keyword(s):  
Healing Process ◽  
Healing Time ◽  
The Self ◽  
Asphalt Pavements ◽  
Self Healing ◽  
Microstructure Observation ◽  
Micro Cracks ◽  
Healing Efficiency ◽  
Healing Temperature ◽  
The Individual

It has become one of the research directions of intelligent materials for self-healing asphalt pavements to use a bionic microvascular containing oily rejuvenator. The rejuvenator in a microvascular can carry out the healing of asphalt micro-cracks, thus reducing the damage to and prolonging the life of asphalt pavement. The aim of this work was to investigate the smart self-healing capability of an asphalt/microvascular material through its microstructure and mechanical properties. Microstructure observation indicated no interface separation between the microvasculars and bitumen matrix. Micro-CT images showed that microvasculars dispersed in asphalt samples without accumulation or tangles. The phenomenon of microcracks healing without intervention was observed, which proved that the fractured asphalt sample carried out the self-healing process with the help of rejuvenator diffusing out from the broken microvasculars. The self-healing efficiency of asphalt samples was also evaluated through a tensile test considering the factors of microvasculars content, healing time and healing temperature. It was found that the tensile strength of the asphalt samples was greatly enhanced by the addition of microvasculars under a set test condition. Self-healing efficiency was enhanced with more broken microvasculars in the rupture interface of the asphalt sample. During two self-healing cycles, the self-healing efficiency of the asphalt sample with three microvascular per 1 cm2 of a broken interface were able to reach 80% and 86%. This proves that microvasculars containing rejuvenator play a practical role in the self-healing process of asphalt. With an increase in temperature from 0 to 30 °C, the self-healing capability of the asphalt samples increased dramatically. An increase in time increased the self-healing capability of the bitumen samples. At last, a preliminary mathematical model also deduced that the self-healing efficiency was determined by the individual healing steps, including release, penetration and diffusion of the rejuvenator agent.

Reservation and Development of Rigid Pavement Quality with the Aid of Bacteria

2021 ◽  
Author(s):  
Saad Sarsam ◽  
◽  
Mohammed Sulaiman ◽  
Keyword(s):  
Service Life ◽  
Healing Process ◽  
Strength Properties ◽  
Water Bath ◽  
Self Healing ◽  
Calcium Carbonate Precipitation ◽  
Rigid Pavement ◽  
Flexure Strength ◽  
Healing Agent ◽  
Wheel Loading

Initiation of Microcracks in rigid pavement usually starts within few hours of casting due to the shrinkage of concrete and casting at hot environment condition. Cracking proceeds and changes to macrocracks throughout the service life of the pavement due to repetitions of compressive, tensile, and shear stress under wheel loading. Such cracking exhibits a durability problem since the ingress of moisture and harmful chemicals such as sulphates and chlorides into the concrete through the cracks can cause premature matrix degradation and corrosion of embedded steel reinforcement at joints, which may result in the decrement of strength and service life. In this work, implementation of self-healing techniques was adopted with the aid of bacteria and healing agent to precipitate CaCo3 on the formed micro-cracks. The precipitation of calcite by continuous hydration of cement helps in production of calcium carbonate precipitation with the help of bacteria. A soil bacterium named Bacillus subtilis was cultured in the laboratory, the concentration of bacteria cell of B. subtilits in normal saline (NaCl, 9 g/l) suspension was 106 cell/ml. Concrete specimens of various type (cube of 100x100x100 mm, cylinder of 100mm diameter and 200mm height, and beam of 100 x 100 x 500 mm) size have been prepared in the laboratory, then separated to three sets. The first set of specimens were subjected to controlled compression and flexure pre-cracking, then subjected to healing and curing in a water bath which contains the prementioned bacteria at 20°C for 7 days. The second set was the control specimens cured in water bath for 7 and 28 days at 20°C. The third set of specimens were subjected to healing and curing in a water bath which contains the prementioned bacteria at 20°C for 7 and 28 days and then tested for compressive, indirect tensile, and flexure properties. It was observed that the healing process provided by the bacteria have improved the overall properties of concrete by (23, 11 and 16) % for compressive, tensile and flexure strength respectively as compared to those of control mixture after 28 days of curing. On the other hand, specimens subjected to controlled pre-cracking exhibit improvement in strength properties after the healing process provided by the bacteria by (28 and 33) % for compressive and flexure strength respectively as compared to those of control mixture after 7 days of curing. It was concluded that spraying of bacterial water for curing the concrete is beneficial and can be considered as sustainable and environment friendly solution for maintenance. Bacteria can reserve, develop and maintain the quality of rigid pavement.

Continuum damage-healing framework for the hydration induced self-healing of the cementitious composite

2020 ◽  
pp. 105678952096803
Author(s):  
Qing Chen ◽  
Xiangyong Liu ◽  
Hehua Zhu ◽  
J Woody Ju ◽  
Xie Yongjian ◽  
...  
Keyword(s):  
Healing Process ◽  
Healing Time ◽  
Continuum Damage ◽  
Self Healing ◽  
Hydration Products ◽  
Cementitious Composite ◽  
Hydration Kinetics ◽  
Micro Cracks ◽  
Damage Healing ◽  
Healing Model

The self-healing materials have become more and more popular due to their active capacity of repairing the (micro-) damages, such as the (micro-) cracks, the (micro-) voids and the other defects. In this paper, the thermodynamic based damage-healing framework is presented for the hydration induced self-healing composite with a compatible healing variable. The new variable is incorporated to consider the time-dependent properties of the hydration products, with which a new damage healing law is proposed. The hydration kinetics are employed to describe the healing process. The properties of the hydration products are arrived with the multiscale and multilevel homogenization scheme. The presented damage-healing model is applied to an isotropic cementitious composite under the tensile loading histories. The presented framework is compared with the classic continuum damage-healing theory and the experimental data. The results show that the presented damage-healing model is capable of describing the hydration induced self-healing of the cementitious composite. It can describe the behavior of the partially and fully healed concrete material. The effects of the healing time and the compatible healing variables on the damage-healing results are investigated based on our proposed framework.

scholarly journals Injectable Self-Healing Adhesive pH-Responsive Hydrogels Accelerate Gastric Hemostasis and Wound Healing

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Jiahui He ◽  
Zixi Zhang ◽  
Yutong Yang ◽  
Fenggang Ren ◽  
Jipeng Li ◽  
...  
Keyword(s):  
Wound Healing ◽  
Endoscopic Treatment ◽  
Healing Process ◽  
Gelation Time ◽  
Type I ◽  
Self Healing ◽  
Ph Responsive ◽  
Gastric Hemorrhage ◽  
Wound Model ◽  
Arterial Bleeding

AbstractEndoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are well-established therapeutics for gastrointestinal neoplasias, but complications after EMR/ESD, including bleeding and perforation, result in additional treatment morbidity and even threaten the lives of patients. Thus, designing biomaterials to treat gastric bleeding and wound healing after endoscopic treatment is highly desired and remains a challenge. Herein, a series of injectable pH-responsive self-healing adhesive hydrogels based on acryloyl-6-aminocaproic acid (AA) and AA-g-N-hydroxysuccinimide (AA-NHS) were developed, and their great potential as endoscopic sprayable bioadhesive materials to efficiently stop hemorrhage and promote the wound healing process was further demonstrated in a swine gastric hemorrhage/wound model. The hydrogels showed a suitable gelation time, an autonomous and efficient self-healing capacity, hemostatic properties, and good biocompatibility. With the introduction of AA-NHS as a micro-cross-linker, the hydrogels exhibited enhanced adhesive strength. A swine gastric hemorrhage in vivo model demonstrated that the hydrogels showed good hemostatic performance by stopping acute arterial bleeding and preventing delayed bleeding. A gastric wound model indicated that the hydrogels showed excellent treatment effects with significantly enhanced wound healing with type I collagen deposition, α-SMA expression, and blood vessel formation. These injectable self-healing adhesive hydrogels exhibited great potential to treat gastric wounds after endoscopic treatment.

Self-Healing and Repairing Concrete Cracks Based on Bio-Mineralization

2014 ◽  
Vol 629-630 ◽  
pp. 494-503 ◽  
Author(s):  
Chun Xiang Qian ◽  
Mian Luo ◽  
Li Fu Ren ◽  
Rui Xing Wang ◽  
Rui Yang Li ◽  
...  
Keyword(s):  
Concrete Surface ◽  
Cellular Respiration ◽  
Self Healing ◽  
Capillary Suction ◽  
Water Permeation ◽  
Carbonate Ions ◽  
Micro Cracks ◽  
Small Cracks ◽  
The Common ◽  
The One

In this paper, three bio-mineralization mechanisms were proposed to repair cement-based materials cracks. The common feature is that the three are all induced by bacterial. A type of bacterial which can decompose urea and release carbonate ions could be applied to repair micro cracks on concrete surface when combining calcium ions. But what need to be noted is that the way of repairing cracks is passive. Some alkaliphilic bacterial spores could be added to concrete when casted and two different types of bacterial were used to realize the function of self-healing. The sources of carbonate ions made them different, the one release carbonate dioxide through its own cellular respiration, the other could transfer carbon dioxide in air to bicarbonate. Coefficient of capillary suction, apparent water permeation coefficient and area repairing rate were applied to characterize the repairing effectiveness. The tests results were that all three bio-mineralization mechanisms showed excellent repair effect to small cracks formed at early ages. When the bacteria were immobilized by ceramsite, the self-healing effect could be improved for the cracks formed at late ages.

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