Towards a Bacteria-Based Agent to Make Concrete Self-Healing

2012 ◽  
Vol 1488 ◽  
Author(s):  
Renee M. Mors ◽  
Henk M. Jonkers
Keyword(s):  
Cement Hydration ◽  
Calcium Lactate ◽  
Strength Development ◽  
Self Healing ◽  
Standard Mixture ◽  
Organic Salts ◽  
Organic Mineral ◽  
Healing Agent ◽  
Polycarboxylate Ether ◽  
Concrete Matrix

ABSTRACTA bacteria-based healing agent for concrete is currently under development in the Microlab of TU Delft. The agent consists of organic mineral precursor compound and bacteria in a protective reservoir. Cracks in the concrete matrix may be sealed and blocked by calcium carbonate based crystals, formed by bacterial conversion of mineral precursor compound. Given the solubility of the agent components, healing agent material may be prematurely released during the wet mixing stage, potentially influencing cement hydration and functionality of other concrete additions. Several materials have been selected as potential mineral precursor compound, being organic salts and a carbohydrate. Tests on standard mortar specimens show that strength development is not compromised when calcium lactate is added to the standard mixture. Calcium lactate was added to the mortar mixture either pure or in combination with a superplasticizer, either based on sulfonated naphthalene or modified polycarboxylate ether, to determine possible interferential effects.

Effect of Poly(Ethylene-co-Vinyl Acetate) as a Self-Healing Agent in Geopolymer Exposed to Various Curing Temperatures

2016 ◽  
Vol 841 ◽  
pp. 16-20 ◽  
Author(s):  
Andri Kusbiantoro ◽  
Norbaizurah Rahman ◽  
Siew Choo Chin ◽  
Ridho Bayu Aji
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Vinyl Acetate ◽  
Heat Exposure ◽  
Ethylene Vinyl Acetate ◽  
Strength Development ◽  
Self Healing ◽  
Heat Curing ◽  
Healing Agent ◽  
Poly Ethylene

The elevated temperature curing could cause rapid evaporation of moisture from geopolymer framework, which in turn will trigger a drying shrinkage to the specimen and affect the performance of hardened geopolymer. Different studies have been done on the characteristics of fly ash based geopolymer, yet scarce studies are available on the addition of self-healing agent to reduce shrinkage phenomenon during heat curing. This study experimentally examines the effect of PVA (poly ethylene vinyl acetate) as a self-healing agent on the mechanical properties of geopolymer mortar after 24 hours curing in various temperatures. The effect of PVA was evaluated at 1% of fly ash weight in geopolymer mixture with various curing temperatures of 70, 80, and 90 oC. The curing process of geopolymer mortar was done for 24 hours without any post-cast detainment period. Compressive strength and porosity tests were conducted to provide fundamental information on the hardened properties of geopolymer mortar. Based on the results, 90oC heat curing showed higher improvement on compressive strength properties than other specimens. Strength development of geopolymer mortar was also affected by various geopolymerization rate that relies on the heat exposure.

scholarly journals Bacillus Subtilis as Self-Healing Agent in Cement Mortar: The Effect of Curing Time and Amount of Calcium Lactate on Strength

2021 ◽  
Vol 40 (4) ◽  
pp. 889-897
Author(s):  
Sohail Muhammad ◽  
Humair Ahmed Siddiqui
Keyword(s):  
Compressive Strength ◽  
Bacillus Subtilis ◽  
Calcium Carbonate ◽  
Cement Mortar ◽  
Calcium Lactate ◽  
Self Healing ◽  
Curing Time ◽  
Healing Agent ◽  
Cause Of Failure ◽  
The Cost

Crack growth is a major cause of failure in structures that are made using cement and concrete. Healing of these cracks can increase the life span of structures. In the present study micro-organism based self-healing of structures is studied. A commonly occurring micro-organism bacterium called Bacillus Subtilis, is used in the manufacturing of cement mortar blocks as a self-healing agent for cement mortar blocks, with the use of Calcium Lactate as feed for bacteria. In the first step, colonies of Bacillus Subtilis were grown and added with calcium lactate to produce a solution. The solution was then kept for one week to observe the metabolic product of Bacillus Subtilis. It was found that the bacterial product was composed of CaCO3 and thus the bacteria is suitable to be used as self-healing agent. Self-healing cement mortar blocks were made by adding Bacteria and Calcium Lactate with usual ingredients of cement mortar, i.e. cement, sand and water. It was found that the bacteria were also effective in converting Calcium Lactate to Calcium Carbonate, when mixed in cement mortar blocks. It was observed that the pores of cement mortar blocks were filled by Calcium Carbonate and that cracks get healed by the deposition of Calcium Carbonate in the cracks. Cement mortar blocks, with and without healing agent, were made to compare the effect of curing time. The samples were tested after seven, fourteen and twenty-eight days to compare the effect of healing agent. All the samples with the healing agent showed a higher compressive strength in comparison with the samples that were made without healing agent. Different percentages of Calcium Lactate, ranging from 1-7% were also used to find the best composition for future use. It was found that the compressive strength was increasing up to 5% while above 5% the increase was marginal thus it is proposed that Calcium Lactate should be used in between 5-7 % to reduce the cost of self-healing cement in construction industry.

scholarly journals The influence of SAPs on chloride ingress in cracked concrete

2019 ◽  
Vol 289 ◽  
pp. 08007 ◽  
Author(s):  
Tim Van Mullem ◽  
Robby Caspeele ◽  
Nele De Belie
Keyword(s):  
Chloride Solution ◽  
Chloride Ingress ◽  
Self Healing ◽  
Cracked Concrete ◽  
Chloride Migration ◽  
Swelling Capacity ◽  
Healing Agent ◽  
Additional Water ◽  
Lower Chloride ◽  
Concrete Matrix

Super Absorbent Polymers (SAPs) have proven to be effective as a self-healing agent for regaining the liquid tightness of cracked concrete. This is due to their large swelling capacity which allows them to (partially) block cracks which are in contact with water or moisture. Additionally, they are able to release this water when the climate becomes drier, thereby promoting the autogenous healing capacity of the concrete matrix. The effect SAPs have on chloride migration into cracked concrete is still unknown. The swelling capacity of the SAPs might partially block the crack, but this does not necessarily mean that the chloride ingress into the crack is lower. Especially, since the porosity of concrete with SAPs is slightly higher when additional water is added to compensate for the loss in workability. This paper compares the chloride ingress in cracked mortar with and without SAPs. The specimens were saturated in a chloride solution during 1 or 5 weeks after which the chloride ingress could be visualised using silver nitrate. The specimens which healed prior to chloride saturation had a significantly lower chloride ingress. The SAPs were able to delay the chloride ingress, as well as limit the influence of the crack on the chloride ingress.

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.

Numerical investigation into effect of self-healing composite microcapsules thickness and diameter on their failure strength

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Raj Kumar Pittala ◽  
Satish Ben B. ◽  
Syam Kumar Chokka ◽  
Niranjan Prasad
Keyword(s):  
Matrix Composite ◽  
Polymer Matrix ◽  
Shell Thickness ◽  
Polymer Matrix Composite ◽  
Thickness Effect ◽  
Failure Strength ◽  
Self Healing ◽  
Content Type ◽  
Reinforced Polymer ◽  
Healing Agent

Purpose Microcapsule-embedded autonomic healing materials have the ability to repair microcracks when they come into contact with the crack by releasing the healing agent. The microcapsules with specific shape and thickness effect in releasing healing agent to the cracked surfaces. Thus, the purpose of this paper is to know the load bearing capacity of the self-healing microcapsules and the stresses developed in the material. Design/methodology/approach In the present study, self-healing microcapsule is modelled and integrated with the polymer matrix composite. The aim of the present study is to investigate failure criteria of Poly (methyl methacrylate) microcapsules by varying the shell thickness, capsule diameter and loading conditions. The strength of the capsule is evaluated by keeping the shell thickness as constant and varying the capsule diameter. Uniformly distributed pressure loads were applied on the capsule-reinforced polymer matrix composite to assess the failure strength of capsules and composite. Findings It is observed from the results that the load required to break the capsules is increasing with the increase in capsule diameter. The failure strength of microcapsule with 100 µm diameter and 5 µm thickness is observed as 255 MPa. For an applied load range of 40–160 N/mm2 on the capsules embedded composite, the maximum stress developed in the capsules is observed as 308 MPa. Originality/value Failure strengths of microcapsules and stresses developed in the microcapsule-reinforced polymer composites were evaluated.

scholarly journals Reversible Assembly of Terpyridine Incorporated Norbornene-Based Polymer via a Ring-Opening Metathesis Polymerization and Its Self-Healing Property

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1173 ◽  
Author(s):  
Jookyeong Lee ◽  
Hwi Moon ◽  
Keewook Paeng ◽  
Changsik Song
Keyword(s):  
Ring Opening ◽  
Transition Metal Ions ◽  
Self Healing ◽  
Ring Opening Metathesis Polymerization ◽  
Metathesis Polymerization ◽  
Ligand Interactions ◽  
Healing Agent ◽  
Healing Property ◽  
External Stimuli ◽  
Metal Ligand

We induced a terpyridine moiety into a norbornene-based polymer to demonstrate its self-healing property, without an external stimulus, such as light, heat, or healing agent, using metal–ligand interactions. We synthesized terpyridine incorporated norbornene-based polymers using a ring-opening metathesis polymerization. The sol state of diluted polymer solutions was converted into supramolecular assembled gels, through the addition of transition metal ions (Ni2+, Co2+, Fe2+, and Zn2+). In particular, a supramolecular complex gel with Zn2+, which is a metal with a lower binding affinity, demonstrated fast self-healing properties, without any additional external stimuli, and its mechanical properties were completely recovered.

Microencapsulation of UV-Curable Self-healing Agent for Smart Anticorrosive Coating

2014 ◽  
Vol 27 (5) ◽  
pp. 607-615 ◽  
Author(s):  
Dong Zhao ◽  
Mo-zhen Wang ◽  
Qi-chao Wu ◽  
Xiao Zhou ◽  
Xue-wu Ge
Keyword(s):  
Self Healing ◽  
Uv Curable ◽  
Anticorrosive Coating ◽  
Healing Agent

scholarly journals Reutilizing Waste Iron Tailing Powders as Filler in Mortar to Realize Cement Reduction and Strength Enhancement

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 541
Author(s):  
Liyun Cui ◽  
Peiyuan Chen ◽  
Liang Wang ◽  
Ying Xu ◽  
Hao Wang
Keyword(s):  
Cement Hydration ◽  
Mercury Intrusion Porosimetry ◽  
Economic Cost ◽  
Strength Development ◽  
Effective Utilization ◽  
Strength Enhancement ◽  
Nucleation Effect ◽  
Practical Engineering ◽  
Internal Mechanism ◽  
Massive Accumulation

Recently, the massive accumulation of waste iron tailings powder (WITP) has resulted in significant environmental pollution. To solve this problem, this paper proposes an original mortar replacement (M) method to reuse waste solids and reduce cement consumption. In the experiment, the author employed an M method which replaces water, cement, and sand with WITP under constant water/cement and found that the strength development can be significantly improved. Specifically, a mortar with 20% WITP replacement can obtain a 30.95% improvement in strength development. To study the internal mechanism, we performed experiments such as thermogravimetric analysis (TGA), mercury intrusion porosimetry (MIP), and SEM. The results demonstrate that the nucleation effect and pozzolanic effect of WITP can help promote cement hydration, and MIP reveals that WITP can effectively optimize pore structure. In addition, 1 kg 20% WITP mortar reduced cement consumption by 20%, which saves 19.98% of the economic cost. Comprehensively, our approach achieves the effective utilization of WITP and provides a favorable reference for practical engineering.

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