scholarly journals Use of Methylcellulose-Based Pellet to Enhance the Bacterial Self-Healing of Cement Composite

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6113
Author(s):  
Indong Jang ◽  
Dasom Son ◽  
Yongjun Son ◽  
Jihyeon Min ◽  
Chongku Yi
Keyword(s):  
Cement Composite ◽  
Bacterial Spores ◽  
Early Age ◽  
Self Healing ◽  
Healing Efficiency ◽  
Alkaline Environments ◽  
New Type ◽  
Main Component ◽  
Early Age Concrete ◽  
Number Of Bacteria

In this study, a new type of bacterial carrier using methylcellulose was presented, and its applicability to self-healing concrete has been explored. Methylcellulose, the main component of a 2 mm pellet-shaped carrier, can remain stable in alkaline environments and expand in neutral or acidic environments. These properties allow bacteria to survive in the high-alkaline and high-pressure environments of early age concrete, and the number of bacteria increases rapidly in the event of cracks, accelerating crack closure. The results show that the survival rate of bacterial spores inside the mortar was increased, and the pellet provides an enhanced biological anchor suitable for bacterial activity, bacterial growth, and mineral precipitation. Further, the results indicate an improved self-healing efficiency compared with mixing bacteria directly into the cement composite.

scholarly journals Effects of Curing Conditions and Supplementary Cementitious Materials on Autogenous Self-Healing of Early Age Cracks in Cement Mortar

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 752
Author(s):  
Mian Luo ◽  
Kang Jing ◽  
Jingquan Bai ◽  
Ziqi Ding ◽  
Dingyi Yang ◽  
...  
Keyword(s):  
Cement Mortar ◽  
Cementitious Materials ◽  
Visual Observation ◽  
Healing Time ◽  
Supplementary Cementitious Materials ◽  
Early Age ◽  
Self Healing ◽  
Replacement Ratio ◽  
Curing Conditions ◽  
Healing Efficiency

The autogenous healing potential of cement-based materials is affected by multiple factors, such as mix composition, crack width, pre-cracking age and external environmental conditions. In this study, the effects of curing conditions and supplementary cementitious materials (SCMs) on autogenous self-healing of early age cracks in cement mortar were investigated. Three curing conditions, i.e., standard curing, wet–dry cycles and incubated in water, and two SCMs, i.e., fly ash (FA) and blast furnace slag (BFS) with various contents (cement replacement ratio at 0%, 20%, and 40%) were examined. A single early age crack (pre-cracking age of 3 days) with a width of 200~300 μm was generated in cylindrical mortar specimens. Autogenous crack self-healing efficiency of mortar specimens was evaluated by performing a visual observation and a water permeability test. Moreover, microstructure analysis (XRD, SEM and TG/DTG) was utilized to characterize the healing products. The results indicated that the presence of water was essential for the autogenous self-healing of early age cracks in cement mortar. The efficiency of self-healing cracks was highest in specimens incubated in water. However, no significant self-healing occurred in specimens exposed to standard curing. For wet–dry cycles, a longer healing time was needed to obtain good self-healing compared to samples incubated in water. SCMs type and content significantly affected the autogenous self-healing ability of early age cracks. The self-healing efficiency of early age cracks decreased with increases in FA and BFS content. BFS mortars exhibited greater recovery in relation to water penetration resistance compared to the reference and FA mortars. Almost the same regain of water tightness and a lower crack-healing ratio after healing of 28 days in FA mortars were observed compared to the reference. The major healing product in the surface cracks of specimens with and without SCMs was micron-sized calcite crystals with a typical rhombohedral morphology.

scholarly journals Preparation and Characterization of Self-Healing Mortar Based on “Build-In” Carbonation

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 644
Author(s):  
Xin Wang ◽  
Wenting Li ◽  
Zhengwu Jiang
Keyword(s):  
Healing Rate ◽  
Cement Mortar ◽  
Setting Time ◽  
Heat Of Hydration ◽  
Self Healing ◽  
Pore Filling ◽  
Healing Efficiency ◽  
Negative Effect ◽  
New Type

In this study, a new type of cement-based healing pellets (CHPs) were proposed to accelerate the healing efficiency of concrete, which was mainly based on the introduced Na2CO3 on promoting the formation of calcium carbonate (CaCO3) in cracks. The effects of Na2CO3 on the characteristics of CHPs were firstly investigated, and then the properties of cement mortar mixed with CHPs were studied quantitatively, including the workability, mechanical properties and healing ability. The results showed that higher dosages of Na2CO3 in CHPs decreased the size range of pellets and reduced the setting time, fluidity and heat of hydration of mortar. Still more, CHPs reduced the early strength of mortar but kept the intensity growth rate stable such that it had nearly no negative effect on the later strength. With the content of CHPs increasing, the strength of mortar showed a decreasing trend, while the pore-filling efficiency and strength healing rate of mortar were further improved. In addition, as a new type of self-healing pellets for concrete based on the “build-in” carbonation, CHPs improved the strength and healing effectiveness of cement mortar. When the dosage of Na2CO3 in CHPs and the content of CHPs in mortar were at 10% and 25%, respectively, mortar obtained highest strength in the later stage and the best healing effect.

scholarly journals Ultrarobust, tough and highly stretchable self-healing materials based on cartilage-inspired noncovalent assembly nanostructure

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yuyan Wang ◽  
Xin Huang ◽  
Xinxing Zhang
Keyword(s):  
Spider Silk ◽  
Self Healing ◽  
High Toughness ◽  
Healing Efficiency ◽  
Strong Interfacial Interaction ◽  
Highly Stretchable ◽  
Noncovalent Bonds ◽  
Actuation Devices ◽  
Noncovalent Bonding ◽  
Polyurethane Matrix

AbstractSelf-healing materials integrated with excellent mechanical strength and simultaneously high healing efficiency would be of great use in many fields, however their fabrication has been proven extremely challenging. Here, inspired by biological cartilage, we present an ultrarobust self-healing material by incorporating high density noncovalent bonds at the interfaces between the dentritic tannic acid-modified tungsten disulfide nanosheets and polyurethane matrix to collectively produce a strong interfacial interaction. The resultant nanocomposite material with interwoven network shows excellent tensile strength (52.3 MPa), high toughness (282.7 MJ m‒3, which is 1.6 times higher than spider silk and 9.4 times higher than metallic aluminum), high stretchability (1020.8%) and excellent healing efficiency (80–100%), which overturns the previous understanding of traditional noncovalent bonding self-healing materials where high mechanical robustness and healing ability are mutually exclusive. Moreover, the interfacical supramolecular crosslinking structure enables the functional-healing ability of the resultant flexible smart actuation devices. This work opens an avenue toward the development of ultrarobust self-healing materials for various flexible functional devices.

Very early age concrete hydration characterization monitoring using piezoceramic based smart aggregates

2013 ◽  
Vol 22 (8) ◽  
pp. 085025 ◽  
Author(s):  
Qingzhao Kong ◽  
Shuang Hou ◽  
Qing Ji ◽  
Y L Mo ◽  
Gangbing Song
Keyword(s):  
Early Age ◽  
Concrete Hydration ◽  
Early Age Concrete

scholarly journals Intrinsic Self-Healing Epoxies in Polymer Matrix Composites (PMCs) for Aerospace Applications

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 201
Author(s):  
Stefano Paolillo ◽  
Ranjita K. Bose ◽  
Marianella Hernández Santana ◽  
Antonio M. Grande
Keyword(s):  
High Performance ◽  
Polymer Matrix Composites ◽  
Critical Issue ◽  
General Description ◽  
Self Healing ◽  
Matrix Composites ◽  
Testing Procedures ◽  
Aerospace Applications ◽  
Polymer Properties ◽  
Healing Efficiency

This article reviews some of the intrinsic self-healing epoxy materials that have been investigated throughout the course of the last twenty years. Emphasis is placed on those formulations suitable for the design of high-performance composites to be employed in the aerospace field. A brief introduction is given on the advantages of intrinsic self-healing polymers over extrinsic counterparts and of epoxies over other thermosetting systems. After a general description of the testing procedures adopted for the evaluation of the healing efficiency and the required features for a smooth implementation of such materials in the industry, different self-healing mechanisms, arising from either physical or chemical interactions, are detailed. The presented formulations are critically reviewed, comparing major strengths and weaknesses of their healing mechanisms, underlining the inherent structural polymer properties that may affect the healing phenomena. As many self-healing chemistries already provide the fundamental aspects for recyclability and reprocessability of thermosets, which have been historically thought as a critical issue, perspective trends of a circular economy for self-healing polymers are discussed along with their possible advances and challenges. This may open up the opportunity for a totally reconfigured landscape in composite manufacturing, with the net benefits of overall cost reduction and less waste. Some general drawbacks are also laid out along with some potential countermeasures to overcome or limit their impact. Finally, present and future applications in the aviation and space fields are portrayed.

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