scholarly journals Evaluation of the Compatibility of Modified Encapsulated Sodium Silicate for Self-Healing of Cementitious Composites

2021 ◽  
Vol 11 (22) ◽  
pp. 10847
Author(s):  
Abdulmohaimen Imad Mohammed ◽  
Ahmed Awadh Ahmed Ba Rahman ◽  
Noor Azline Mohd Nasir ◽  
Nabilah Abu Bakar ◽  
Nor Azizi Safiee
Keyword(s):  
Bonding Strength ◽  
Healing Process ◽  
High Strength ◽  
Cementitious Composites ◽  
Survival Ratio ◽  
Self Healing ◽  
Mixing Process ◽  
Strength Recovery ◽  
Healing Agent ◽  
Analysis Survival

Healing agent carriers play a significant role in defining the performance of the autonomous self-healing system. Particularly, the ability to survive during the mixing process and the release of the healing agent when cracks occur without affecting the mechanical properties of the cementitious composite. Up to now, these issues are still a concern since glass capsules are unable to survive the mixing process, while some types of microcapsules were reported to cause a decrement in strength as well as limited strength recovery. Therefore, this study was twofold, addressing the surface treatment of polystyrene (PS) capsules and the evaluation of the compatibility of the modified capsules for cement-based applications. Secondly, assessing the healing performance of modified PS capsules in cementitious composites. Furthermore, the study also evaluates the potential healing performance due to the synergic effect between the encapsulation method and the autogenous self-healing mechanism. The investigation was carried out by measuring the changes in the pH of pore solution, FTIR analysis, survival ratio, and bonding strength. For self-healing assessment, the compression cracks on the cement paste were created at an early age and the strength recovery was measured at the age of 28 and 56 days. To identify the chemical compounds responsible for the healing process, SEM-EDX tests were conducted. Moreover, the effect of silica fume (SF) on bonding strength and self-healing was also evaluated. Based on the results, the modified PS capsules by roughing approach showed promising performance in terms of survivability, bonding, and recovery. The modified PS capsule increased the strength recovery by about 12.5–15% for 100%OPC and 95%OPC + 5%SF, respectively. The finding observed that the combining of modified PS capsules and the inclusion of SF gave high strength recovery of about 20% compared to 100%OPC without capsules. Thus, the modified PS capsule has a good potential for self-healing of cementitious-based applications.

Mechanical responses of microencapsulated self-healing cementitious composites under compressive loading based on a micromechanical damage-healing model

2021 ◽  
pp. 105678952110112
Author(s):  
Kaihang Han ◽  
Jiann-Wen Woody Ju ◽  
Yinghui Zhu ◽  
Hao Zhang ◽  
Tien-Shu Chang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Micromechanical Model ◽  
Cementitious Composites ◽  
Self Healing ◽  
Damage Degree ◽  
Healing Efficiency ◽  
The Matrix ◽  
Healing Agent ◽  
Damage Healing

The cementitious composites with microencapsulated healing agents have become a class of hotspots in the field of construction materials, and they have very broad application prospects and research values. The in-depth study on multi-scale mechanical behaviors of microencapsulated self-healing cementitious composites is critical to quantitatively account for the mechanical response during the damage-healing process. This paper proposes a three-dimensional evolutionary micromechanical model to quantitatively explain the self-healing effects of microencapsulated healing agents on the damage induced by microcracks. By virtue of the proposed 3 D micromechanical model, the evolutionary domains of microcrack growth (DMG) and corresponding compliances of the initial, extended and repaired phases are obtained. Moreover, the elaborate studies are conducted to inspect the effects of various system parameters involving the healing efficiency, fracture toughness and preloading-induced damage degrees on the compliances and stress-strain relations. The results indicate that relatively significant healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will lead to a higher compressive strength and stiffness. However, the specimen will break owing to the nucleated microcracks rather than the repaired kinked microcracks. Further, excessive higher values of healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will not affect the compressive strength of the cementitious composites. Therefore, a stronger matrix is required. To achieve the desired healing effects, the specific parameters of both the matrix and microcapsules should be selected prudently.

Research on PA Heat-Melt Adhesive Being Used as Self-Healing Agent in Cementitious Materials

2011 ◽  
Vol 374-377 ◽  
pp. 1899-1903
Author(s):  
Xiong Zhou Yuan ◽  
Wei Sun ◽  
Xiao Bao Zuo
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Chemical Stability ◽  
Bonding Strength ◽  
Research Team ◽  
Cementitious Materials ◽  
Experimental Results ◽  
Self Healing ◽  
Detailed Consideration ◽  
Healing Agent

Based on detailed consideration of the autonomic healing concept of microencapsulated healing agent, micro- bacteria induced calcite and shape memory alloys, our research team proposed a new self-healing technique coupled with of SMA and heat-melt adhesive. In this article, chemical stability and bonding strength with cementitious materials of PA heat-melt adhesive were tested. Experimental results show that PA heat-melt adhesive may contain the ability being used in self-healing techniques coupled with SMA.

scholarly journals Tracking capsule activation and crack healing in a microcapsule-based self-healing polymer

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
S. A. McDonald ◽  
S. B. Coban ◽  
N. R. Sottos ◽  
P. J. Withers
Keyword(s):  
Healing Process ◽  
Polymeric Materials ◽  
Time Lapse ◽  
Repair Process ◽  
Three Dimensions ◽  
Crack Plane ◽  
Self Healing ◽  
Crack Healing ◽  
Healing Agent ◽  
First Time

AbstractStructural polymeric materials incorporating a microencapsulated liquid healing agent demonstrate the ability to autonomously heal cracks. Understanding how an advancing crack interacts with the microcapsules is critical to optimizing performance through tailoring the size, distribution and density of these capsules. For the first time, time-lapse synchrotron X-ray phase contrast computed tomography (CT) has been used to observe in three-dimensions (3D) the dynamic process of crack growth, microcapsule rupture and progressive release of solvent into a crack as it propagates and widens, providing unique insights into the activation and repair process. In this epoxy self-healing material, 150 µm diameter microcapsules within 400 µm of the crack plane are found to rupture and contribute to the healing process, their discharge quantified as a function of crack propagation and distance from the crack plane. Significantly, continued release of solvent takes place to repair the crack as it grows and progressively widens.

Finite Element Modelling and Analysis of Micro-Capsule Based Self-Healing Polymeric Composites

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
J. Lilly Mercy ◽  
S. Prakash
Keyword(s):  
Polymer Matrix ◽  
Healing Process ◽  
Polymeric Composites ◽  
Polymerization Reaction ◽  
Self Healing ◽  
Functional Composites ◽  
Laminate Theory ◽  
Static Mechanical ◽  
Healing Agent ◽  
The Many

Self-healing polymeric composites are a class of functional composites which heal itself during damage. Out of the many methods of self-healing, micro-capsule based self-healing process is the proven and established method where the healing agent stored in the capsule breaks and seals up the gap after the polymerization reaction with the suitable catalyst. The incorporation of the capsule in a polymer matrix in a random fashion makes it challenging to model the composite material. This paper explains the modelling and simulation of the self-healing composite using MIDAS NFX FEA software. The effect of self-healing composition - micro-capsule size and concentration on the static mechanical properties of the composite is explored. The capsules are integrated in the polymer matrix as a representative volume element using the rule of mixtures. The classical laminate theory was used to identify the critical ply failure.

scholarly journals Biological Self-Healing of Cement Paste and Mortar by Non-Ureolytic Bacteria Encapsulated in Alginate Hydrogel Capsules

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3711
Author(s):  
Mohammad Fahimizadeh ◽  
Ayesha Diane Abeyratne ◽  
Lee Sui Mae ◽  
R. K. Raman Singh ◽  
Pooria Pasbakhsh
Keyword(s):  
Cement Paste ◽  
Healing Process ◽  
Cementitious Materials ◽  
The Self ◽  
Self Healing ◽  
Alkaline Conditions ◽  
Healing Agent ◽  
Encapsulated Bacteria ◽  
The Right

Crack formation in concrete is one of the main reasons for concrete degradation. Calcium alginate capsules containing biological self-healing agents for cementitious materials were studied for the self-healing of cement paste and mortars through in vitro characterizations such as healing agent survivability and retention, material stability, and biomineralization, followed by in situ self-healing observation in pre-cracked cement paste and mortar specimens. Our results showed that bacterial spores fully survived the encapsulation process and would not leach out during cement mixing. Encapsulated bacteria precipitated CaCO3 when exposed to water, oxygen, and calcium under alkaline conditions by releasing CO32− ions into the cement environment. Capsule rupture is not required for the initiation of the healing process, but exposure to the right conditions are. After 56 days of wet–dry cycles, the capsules resulted in flexural strength regain as high as 39.6% for the cement mortar and 32.5% for the cement paste specimens. Full crack closure was observed at 28 days for cement mortars with the healing agents. The self-healing system acted as a biological CO32− pump that can keep the bio-agents retained, protected, and active for up to 56 days of wet-dry incubation. This promising self-healing strategy requires further research and optimization.

Self-Healing Materials as New Biologically Inspired Materials

2012 ◽  
Vol 16 ◽  
pp. 11-25
Author(s):  
Fabrizia Ghezzo ◽  
Xi Geng Miao
Keyword(s):  
Failure Mechanisms ◽  
Matrix Material ◽  
High Strength ◽  
Self Healing ◽  
Micro Cracks ◽  
Specific Objective ◽  
Wide Range ◽  
The Matrix ◽  
Safety And Reliability ◽  
Healing Agent

Lightweight, high strength fibre-reinforced polymeric composites are leading materials in many advanced applications including biomedical components. These materials offer the feasibility to incorporate multi functionalities due to their internal architecture, heterogeneity of materials and the flexibility of combining them using currently available fabrication methods. In spite of the excellent properties of these materials, their failure is still a questionable and not well predicted event. Delamination, debonding and micro-cracks are only some of the failure mechanisms that affect the matrices of polymer based composites. More complex cases exist with the combination of multiple failure mechanisms. In such cases a self-repairing mechanism that can be auto-triggered in the matrix material once the crack has been formed, would be very beneficial for all the applications of these materials, reducing maintenance costs and increasing their safety and reliability. Self-healing materials have been studied for more than a decade by now, with the specific objective of reducing the risks and costs of cracking and damage in a wide range of materials. Different approaches have been taken to create such materials, depending on the kind of material that needs to be repaired. The most popular methods developed for polymers and polymer reinforced composites are considered in this review. These methods include materials with micro-capsules containing a healing agent, and composites with matrices that can self-heal the cracks by repairing the broken molecular links upon external heating. While the first approach to healing has been widely used and studied in the past decade, in this review we focus on the second approach since less is reported in the literature and more difficult is the development of the materials based on such a method.

scholarly journals Impact of Bio-Carrier Immobilized with Marine Bacteria on Self-Healing Performance of Cement-Based Materials

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4164 ◽  
Author(s):  
Hayeon Kim ◽  
Hyeongmin Son ◽  
Joonho Seo ◽  
H. K. Lee
Keyword(s):  
Mechanical Properties ◽  
Mercury Intrusion Porosimetry ◽  
Tap Water ◽  
Bottom Ash ◽  
Self Healing ◽  
Mixing Process ◽  
Mercury Intrusion ◽  
Healing Efficiency ◽  
Cement Based Materials ◽  
Healing Agent

The present study evaluated the self-healing efficiency and mechanical properties of mortar specimens incorporating a bio-carrier as a self-healing agent. The bio-carrier was produced by immobilizing ureolytic bacteria isolated from seawater in bottom ash, followed by surface coating with cement powder to prevent loss of nutrients during the mixing process. Five types of specimens were prepared with two methods of incorporating bacteria, and were water cured for 28 days. To investigate the healing ratio, the specimens with predefined cracks were treated by applying a wet–dry cycle in three different conditions, i.e., seawater, tap water, and air for 28 days. In addition, a compression test and a mercury intrusion porosimetry analysis of the specimens were performed to evaluate their physico-mechanical properties. The obtained results showed that the specimen incorporating the bio-carrier had higher compressive strength than the specimen incorporating vegetative cells. Furthermore, the highest healing ratio was observed in specimens incorporating the bio-carrier. This phenomenon could be ascribed by the enhanced bacterial viability by the bio-carrier.

scholarly journals Self-healing of bio-cementitious mortar incubated within neutral and acidic soil

2021 ◽  
Vol 54 (2) ◽  
Author(s):  
Mohamed Esaker ◽  
Omar Hamza ◽  
Adam Souid ◽  
David Elliott
Keyword(s):  
Soil Ph ◽  
Healing Process ◽  
Chemical Exposure ◽  
Acidic Soil ◽  
Self Healing ◽  
Chemical Attack ◽  
Before And After ◽  
Ground Conditions ◽  
Neutral Soil ◽  
Healing Agent

AbstractThe efficiency of bio self-healing of pre-cracked mortar specimens incubated in sand was investigated. The investigation examined the effect of soil pH representing industrially recognised classes of exposure, ranging from no risk of chemical attack (neutral pH ≈ 7) to very high risk (pH ≈ 4.5). Simultaneously, the soil was subjected to fully and partially saturated cycles for 120 days to resemble groundwater-level fluctuation. Bacillus subtilis with nutrients were impregnated into perlite and utilised as a bacterial healing agent. The healing agent was added to half of the mortar specimens for comparison purposes. Mineral precipitations were observed in both control and bio-mortar specimens, and the healing products were examined by SEM–EDX scanning. The healing ratio was evaluated by comparing (1) the repair rate of the crack area and (2) by capillary water absorption and sorptivity index—before and after incubation. The results indicated that bacteria-doped specimens (bio-mortar) exhibited the most efficient crack-healing in all incubation conditions i.e. different chemical exposure classes. In the pH neutral soil, the average healing ratios for the control and bio-mortar specimens were 38% and 82%, respectively. However, the healing ratio decreased by 43% for specimens incubated in acidic soil (pH ≈ 4) compared with specimens incubated in neutral soil (pH ≈ 7). The study implies that bio self-healing is generally beneficial for concrete embedded within soil; however, aggressive ground conditions can inhibit the healing process.

Study of Feasibility of Heat Melt Adhesive Being Used in Crack Self-Healing of Cement-Based Materials

2011 ◽  
Vol 99-100 ◽  
pp. 1087-1091 ◽  
Author(s):  
Xiong Zhou Yuan ◽  
Wei Sun ◽  
Xiao Bao Zuo
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Chemical Stability ◽  
Bonding Strength ◽  
Research Team ◽  
Cementitious Materials ◽  
Self Healing ◽  
Detailed Consideration ◽  
Cement Based Materials ◽  
Healing Agent

Based on detailed consideration of the autonomic healing concept of microencapsulated healing agent, micro- bacteria induced calcite and shape memory alloys, our research team proposed a new self-healing technique coupled with of SMA and heat-melt adhesive. In this article, chemical stability and bonding strength with cementitious materials of EVA heat-melt adhesive were tested. Experimental results show that EVA heat-melt adhesive may contain the ability being used in self-healing techniques coupled with SMA.

Fatigue response of a solid state self-healing resin

2020 ◽  
pp. 096739112095509
Author(s):  
Mohd Suzeren Md Jamil ◽  
Noor Nabilah Muhamad ◽  
Wan Naqiuddin Wan Zulrushdi
Keyword(s):  
Fatigue Life ◽  
Solid State ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Healing Process ◽  
Fatigue Tests ◽  
Self Healing ◽  
Healing System ◽  
Healing Agent ◽  
Modified Epoxy

The present work verified the capability of a solid state self-healing system for retarding or arresting fatigue cracks in epoxy materials subjected to cyclic loading at room temperature. A solid state self-healing material is demonstrated using a thermosetting epoxy polymer which was modified by incorporating a linear thermoplastic polydiglycidyl ether bisphenol-A (PDGEBA) as a healing agent. The stress-controlled constant amplitude (CA) tensile fatigue behavior at stress ratio, R = 0.1 and frequency 10 Hz for both the neat and the modified epoxy was investigated. Fatigue life and residual strength degradation were continuously monitored during the fatigue tests. The modified epoxy fatigue life was shown to be increased by ∼50% after healing periods. The fatigue-healing process was proven through the surface and cross-section resin morphology analyses using microscopy optic and scanning electron microscope (SEM). On the whole, the solid state self-healing system has proven to be very effective in obstructing fatigue crack propagation, effectively improved the self-healing polymeric material to achieve higher endurance limits.

Sign in / Sign up

Export Citation Format

Share Document