scholarly journals Quantifying Crack Self-Healing in Concrete with Superabsorbent Polymers under Varying Temperature and Relative Humidity

2021 ◽  
Vol 13 (24) ◽  
pp. 13999
Author(s):  
Ahmed R. Suleiman ◽  
Lei V. Zhang ◽  
Moncef L. Nehdi
Keyword(s):  
Relative Humidity ◽  
Service Life ◽  
Three Dimensional ◽  
Concrete Structures ◽  
Self Healing ◽  
Micro Computed Tomography ◽  
Wetting And Drying ◽  
Superabsorbent Polymers ◽  
Healing Efficiency ◽  
Quantification Analysis

During their service life, concrete structures are subjected to combined fluctuations of temperature and relative humidity, which can influence their durability and service life performance. Self-healing has in recent years attracted great interest to mitigate the effects of such environmental exposure on concrete structures. Several studies have explored the autogenous crack self-healing in concrete incorporating superabsorbent polymers (SAPs) and exposed to different environments. However, none of the published studies to date has investigated the self-healing in concrete incorporating SAPs under a combined change in temperature and relative humidity. In the present study, the crack width changes due to self-healing of cement mortars incorporating SAPs under a combined change of temperature and relative humidity were investigated and quantified using micro-computed tomography and three-dimensional image analysis. A varying dosage of SAPs expressed as a percentage (0.5%, 1%, and 2%) of the cement mass was incorporated in the mortar mixtures. In addition, the influence of other environments such as continuous water submersion and cyclic wetting and drying was studied and quantified. The results of segmentation and quantification analysis of X-ray µCT scans showed that mortar specimens incorporating 1% SAPs and exposed to environments with a combined change in temperature and relative humidity exhibited less self-healing (around 6.58% of healing efficiency). Conversely, when specimens were subjected to cyclic wetting and drying or water submersion, the healing efficiency increased to 19.11% and 26.32%, respectively. It appears that to achieve sustained self-healing of cracks, novel engineered systems that can assure an internal supply of moisture are needed.

scholarly journals Encapsulation Techniques and Test Methods of Evaluating the Bacteria-Based Self-Healing Efficiency of Concrete: A Literature Review

2020 ◽  
Vol 62 (1) ◽  
pp. 63-85
Author(s):  
Rahul Roy ◽  
Emanuele Rossi ◽  
Johan Silfwerbrand ◽  
Henk Jonkers
Keyword(s):  
Service Life ◽  
Polymeric Materials ◽  
Cementitious Materials ◽  
Test Methods ◽  
Self Healing ◽  
Load Factors ◽  
Healing Efficiency ◽  
Healing Agent ◽  
Maximum Crack ◽  
Encapsulated Bacteria

AbstractCrack formation in concrete structures due to various load and non-load factors leading to degradation of service life is very common. Repair and maintenance operations are, therefore, necessary to prevent cracks propagating and reducing the service life of the structures. Accessibility to affected areas can, however, be difficult as the reconstruction and maintenance of concrete buildings are expensive in labour and capital. Autonomous healing by encapsulated bacteria-based self-healing agents is a possible solution. During this process, the bacteria are released from a broken capsule or triggered by water and oxygen access. However, its performance and reliability depend on continuous water supply, protection against the harsh environment, and densification of the cementitious matrix for the bacteria to act. There are vast methods of encapsulating bacteria and the most common carriers used are: encapsulation in polymeric materials, lightweight aggregates, cementitious materials, special minerals, nanomaterials, and waste-derived biomass. Self-healing efficiency of these encapsulated technologies can be assessed through many experimental methodologies according to the literature. These experimental evaluations are performed in terms of quantification of crackhealing, recovery of durability and mechanical properties (macro-level test) and characterization of precipitated crystals by healing agent (micro-level test). Until now, quantification of crack-healing by light microscopy revealed maximum crack width of 1.80mm healed. All research methods available for assesing self-healing efficiency of bacteria-based healing agents are worth reviewing in order to include a coherent, if not standardized framework testing system and a comparative evaluation for a novel incorporated bacteria-based healing agent.

scholarly journals A Brief Overview on Preparation of Self-Healing Polymers and Coatings via Hydrogen Bonding Interactions

Macromol ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 18-36
Author(s):  
Ikhlas Gadwal
Keyword(s):  
Mechanical Property ◽  
Hydrogen Bonding ◽  
Service Life ◽  
Review Article ◽  
Main Topic ◽  
Self Healing ◽  
Paint Coating ◽  
Hydrogen Bonding Interactions ◽  
Healing Efficiency

Self-healing coatings or materials have received significant importance in paint, coating, and other industries, as well as in academia, because of their capability to extend materials service life, improving protection, and ensuring sustainability. This review article emphasizes significant advances accomplished in the preparation and properties of intrinsic self-healing materials exclusively based on hydrogen bonding interactions, with possible applications in coatings and adhesives. The main topic of discussion in this review article is the preparation, healing conditions, healing efficiency, and mechanical property recovery after healing. The last part of the review discusses the conclusions and outlook of self-healing materials.

scholarly journals Evaluation of the Self-Healing Ability of Mortar Mixtures Containing Superabsorbent Polymers and Nanosilica

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 380 ◽  
Author(s):  
Gerlinde Lefever ◽  
Didier Snoeck ◽  
Dimitrios G. Aggelis ◽  
Nele De Belie ◽  
Sandra Van Vlierberghe ◽  
...  
Keyword(s):  
Crack Width ◽  
Mechanical Performance ◽  
Cementitious Material ◽  
The Self ◽  
Optical Measurements ◽  
Self Healing ◽  
Superabsorbent Polymers ◽  
Healing Efficiency ◽  
Good Healing ◽  
External Conditions

Addition of superabsorbent polymers (SAPs) to cementitious mixtures promotes the self-healing ability of the material. When cracking occurs; SAPs present inside the crack will swell upon contact with water and subsequently release this water to stimulate the further hydration of unhydrated cement particles and the calcium carbonate crystallization. However; the inclusion of SAPs affects the mechanical performance of the cementitious material by the creation of macro-pores as water is retracted from the swollen SAP. To counteract the reduction in strength, part of the cement is replaced by nanosilica. In this research, different mixtures containing either SAPs or nanosilica and a combination of both were made. The samples were subjected to wet–dry cycles simulating external conditions, and the self-healing efficiency was evaluated by means of the evolution in crack width, by optical measurements, and a water permeability test. In samples containing SAPs, an immediate sealing effect was observed and visual crack closure was noticed. The smaller influence on the mechanical properties and the good healing characteristics in mixtures containing both nanosilica and SAPs are promising as a future material for use in building applications.

scholarly journals Sustainable self-healing at ultra-low temperatures in structural composites incorporating hollow vessels and heating elements

2016 ◽  
Vol 3 (9) ◽  
pp. 160488 ◽  
Author(s):  
Yongjing Wang ◽  
Duc Truong Pham ◽  
Zhichun Zhang ◽  
Jinjun Li ◽  
Chunqian Ji ◽  
...  
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Low Temperatures ◽  
Three Dimensional ◽  
Natural World ◽  
The Other ◽  
Self Healing ◽  
Structural Composites ◽  
Healing Efficiency ◽  
Structural Composite

Self-healing composites are able to restore their properties automatically. Impressive healing efficiencies can be achieved when conditions are favourable. On the other hand, healing might not be possible under adverse circumstances such as very low ambient temperature. Here, we report a structural composite able to maintain its temperature to provide a sustainable self-healing capability—similar to that in the natural world where some animals keep a constant body temperature to allow enzymes to stay active. The composite embeds three-dimensional hollow vessels with the purpose of delivering and releasing healing agents, and a porous conductive element to provide heat internally to defrost and promote healing reactions. A healing efficiency over 100% at around −60°C was obtained. The effects of the sheets on the interlaminar and tensile properties have been investigated experimentally. The proposed technique can be implemented in a majority of extrinsic self-healing composites to enable automatic recovery at ultra-low temperatures.

Experimental studies on the development of a self-healing cementitious matrix for repair and retrofitting of concrete structures

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Dibyendu Adak ◽  
Donkupar Francis Marbaniang ◽  
Subhrajit Dutta
Keyword(s):  
Service Life ◽  
Mechanical Strength ◽  
Concrete Structure ◽  
Concrete Structures ◽  
The Self ◽  
Self Healing ◽  
Content Type ◽  
Cementitious Matrix ◽  
Healing Period ◽  
Strength And Durability

PurposeSelf-healing concrete is a revolutionary building material that will generally reduce the maintenance cost of concrete constructions. Self-healing of cracks in concrete structure would contribute to a longer service life of the concrete and would make the material more durable and more sustainable. The cementitious mortar with/without incorporating encapsulates at different percentages of slag replacement with the cement mix improves autogenous healing at different ages. Therefore, this study’s aim is to develop a self-healing cementitious matrix for repair and retrofitting of concrete structures.Design/methodology/approachIn the present work, waste straw pipes are used as a capsule, filled with the solution of sodium hydroxide (NaOH), sodium silicate (Na2SiO3) and colloidal nano-silica as self-healing activators. An artificial micro-crack on the control and blended mortar specimens at different percentages of slag replacement with cement (with/without encapsulation) is developed by applying a compressive load of 50% of its ultimate load-carrying capacity. The mechanical strength and ultrasonic pulse velocity, water absorption and chloride ion penetration test are conducted on the concrete specimen before and after the healing period. Finally, the self-healing activity of mortar mixes with/without encapsulation is analysed at different ages.FindingsThe encapsulated mortar mix with 10% of slag content has better self-healing potential than all other mixes considering mechanical strength and durability. The enhancement of the self-healing potential of such mortar mix is mainly due to hydration of anhydrous slag on the crack surface and transformation of amorphous slag to the crystalline phase in presence of encapsulated fluid.Research limitations/implicationsThe self-healing activities of the slag-based cementitious composite are studied for a healing period of 90 days only. The strength and durability performance of the cracked specimen may be increased after a long healing period.Practical implicationsThe outcome of the work will help repair the cracks in the concrete structure and enhances the service life.Originality/valueThis study identifies the addition encapsulates with a self-healing activator fluid that can recover its strength after minor damage.

A MICROCAPSULE TECHNOLOGY BASED SELF-HEALING SYSTEM FOR CONCRETE STRUCTURES

2013 ◽  
Vol 07 (03) ◽  
pp. 1350014 ◽  
Author(s):  
BIQIN DONG ◽  
NINGXU HAN ◽  
MING ZHANG ◽  
XIANFENG WANG ◽  
HONGZHI CUI ◽  
...  
Keyword(s):  
Urea Formaldehyde ◽  
Concrete Structures ◽  
The Self ◽  
Polymerization Reaction ◽  
Formaldehyde Resin ◽  
Self Healing ◽  
Cementitious Composite ◽  
Healing System ◽  
Healing Efficiency ◽  
Healing Agent

In the study, a novel microcapsule technology based self-healing system for concrete structures has been developed. Through situ-polymerization reaction, the microcapsule is formed by urea formaldehyde resin to pack the epoxy material, which is applied to cementitious composite to achieve self-healing effect. The experimental results revealed that the self-healing efficiency of the composite can be accessed from the recovery of the permeability and strength for the cracked cementitious specimens as the healing agent in the microcapsule acting on the cracks directly. Scanning electronic microscope (SEM/EDX) results show that the epoxy resin is released along with the cracking of the cementitious composite and prevent from cracks continued growth. Further studies show that the self-healing efficiency is affected by the pre-loading of composite, particle size of microcapsule, aging duration of healing agent and so on.

CARBONATION INDUCED CORROSION ANALYSIS OF REINFORCED CONCRETE STRUCTURES BASED ON FULL PROBABILISTIC APPROACH – AN INDONESIAN CASE STUDY

2018 ◽  
Vol 4 (1) ◽  
pp. 165
Author(s):  
Herry Prabowo ◽  
Mochamad Hilmy
Keyword(s):  
Service Life ◽  
Probabilistic Approach ◽  
Concrete Structures ◽  
Weather Condition ◽  
Analysis Data ◽  
National Standard ◽  
Concrete Carbonation ◽  
Durability Design ◽  
Starting Point ◽  
Real Performance

The assessment of the service life of concrete structures using the durability design approach is widely accepted nowadays. It is really encouraged that a simulation model can resemble the real performance of concrete during the service life. This paper investigates the concrete carbonation through probabilistic analysis. Data regarding Indonesian construction practice were taken from Indonesian National Standard (SNI). Meanwhile, data related to Indonesian weather condition for instance humidity and temperature are taken from local Meteorological, Climatological, and Geophysical Agency from 2004 until 2016. Hopefully the results can be a starting point for durability of concrete research in Indonesia.

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