The influence of SAPs on chloride ingress in cracked concrete

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.

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

MRS Proceedings ◽

10.1557/opl.2012.1543 ◽

2012 ◽

Vol 1488 ◽

Cited By ~ 1

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.

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Durability of self-healing concrete

MATEC Web of Conferences ◽

10.1051/matecconf/201928901003 ◽

2019 ◽

Vol 289 ◽

pp. 01003 ◽

Cited By ~ 1

Author(s):

Nele De Belie ◽

Bjorn Van Belleghem ◽

Yusuf Çağatay Erşan ◽

Kim Van Tittelboom

Keyword(s):

Corrosion Behaviour ◽

Healing Process ◽

Chloride Ingress ◽

Self Healing ◽

Crack Healing ◽

Nacl Solution ◽

Visual Damage ◽

Chloride Profiles ◽

Cracked Specimens ◽

Concrete Matrix

Application of self-healing concrete reduces the need for expensive maintenance and repair actions. However, the durability of self-healing concrete has only been scarcely investigated. Here, recent results are presented regarding the resistance of self-healing concrete to chloride ingress. For self-healing concrete with macro-encapsulated polyurethane, chloride profiles and electron probe microanalysis indicated that this mechanism was efficient to reduce the chloride penetration into the crack and from the crack into the concrete matrix [1]. Furthermore, the corrosion behaviour of reinforced concrete specimens subjected to cyclic exposure with a NaCl solution was studied [2]. The electrochemical measurements indicated that autonomous crack healing could significantly reduce the corrosion in the propagation stage. No visual damage could be detected on the rebars after 44 weeks of exposure. On the contrary, cracked specimens without integrated self-healing mechanism, reached a state of active corrosion after 10 weeks of exposure and after 26 weeks clear pitting damage was observed on the rebars. While self-healing by encapsulated polyurethane is complete after one day, bacteria-based products take several weeks to heal a 300 µm crack. Bacterial granules containing denitrifying cultures released nitrite as an intermediate metabolic product which protected the reinforcement during the crack healing process [3].

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Autogenous Healing of Cracked Mortar Using Modified Steady-State Migration Test against Chloride Penetration

Sustainability ◽

10.3390/su13179519 ◽

2021 ◽

Vol 13 (17) ◽

pp. 9519

Author(s):

Fahad ul Rehman Abro ◽

Abdul Salam Buller ◽

Tariq Ali ◽

Zain Ul-Abdin ◽

Zaheer Ahmed ◽

...

Keyword(s):

Steady State ◽

Chloride Ions ◽

Test Method ◽

The Self ◽

Chloride Ingress ◽

Self Healing ◽

Migration Test ◽

Steady State Condition ◽

Chloride Migration ◽

Short Period

Concrete is a popular building material all over the world, but because of different physiochemical processes, it is susceptible to crack development. One of the primary deterioration processes of reinforced concrete buildings is corrosion of steel bars within the concrete through these cracks. In this regard, a self-healing technique for crack repair would be the best solution to reduce the penetration of chloride ions inside concrete mass. In this study, a rapid chloride migration (RCM) test was conducted to determine the self-healing capacity of cracked mortar. With the help of the RCM test, the steady-state migration coefficient of cracked and uncracked specimens incorporating expansive and crystalline admixtures was calculated. Based on the rate of change of the chloride ion concentrations in the steady-state condition, the migration coefficient was calculated. Furthermore, bulk electrical conductivity tests were also conducted before and after the migration test to understand the self-healing behavior. It was evident from the test results that the self-healing of cracks was helpful to reduce the penetration of chloride ions and that it enhanced the ability of cracked mortar to restrict the chloride ingress. Using this test method, the self-healing capacity of the new self-healing technologies can be evaluated. The RCM test can be an acceptable technique to assess the self-healing ability of cement-based materials in a very short period, and the self-healing capacity can be characterized in terms of the decrease of chloride migration coefficients.

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Evaluation and comparison of traditional methods and Electron Probe Micro Analysis (EPMA) to determine the chloride ingress perpendicular to cracks in self-healing concrete

Construction and Building Materials ◽

10.1016/j.conbuildmat.2019.116789 ◽

2019 ◽

Vol 227 ◽

pp. 116789 ◽

Cited By ~ 3

Author(s):

Bjorn Van Belleghem ◽

Yury Villagrán Zaccardi ◽

Philip Van den Heede ◽

Kim Van Tittelboom ◽

Nele De Belie

Keyword(s):

Electron Probe ◽

Chloride Ingress ◽

Self Healing ◽

Electron Probe Micro Analysis ◽

Traditional Methods ◽

Micro Analysis

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Effect of epoxy resin healing agent viscosity on the self-healing performance of capsules reinforced polymer composite

Journal of Polymer Research ◽

10.1007/s10965-021-02458-5 ◽

2021 ◽

Vol 28 (4) ◽

Author(s):

Raj Kumar Pittala ◽

Satish Ben B ◽

Avinash Ben B

Keyword(s):

Epoxy Resin ◽

Polymer Composite ◽

The Self ◽

Self Healing ◽

Reinforced Polymer ◽

Healing Agent

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

International Journal of Damage Mechanics ◽

10.1177/10567895211011239 ◽

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.

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

World Journal of Engineering ◽

10.1108/wje-12-2019-0359 ◽

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.

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Experimental and Simulation Study on Diffusion Behavior of Chloride Ion in Cracking Concrete and Reinforcement Corrosion

Advances in Materials Science and Engineering ◽

10.1155/2018/8475384 ◽

2018 ◽

Vol 2018 ◽

pp. 1-14 ◽

Cited By ~ 2

Author(s):

Yongchun Cheng ◽

Yuwei Zhang ◽

Chunli Wu ◽

Yubo Jiao

Keyword(s):

Finite Element ◽

Prediction Models ◽

Chloride Concentration ◽

Chloride Ion ◽

Corrosion Current ◽

Chloride Diffusion ◽

Finite Element Models ◽

Rc Structures ◽

Cracked Concrete ◽

Chloride Migration

A chloride ion is a key factor affecting durability of reinforced concrete (RC) structures. In order to investigate chloride migration in cracked concrete, considering the mesoscopic heterogeneity of concrete, concrete modeled here is treated as a four-phase composite consisting aggregate, mortar, crack, and interfacial transition zone (ITZ). In this paper, two-dimensional finite element models of cracked concrete with different crack widths and crack quantity are established and the control parameters are determined based on the nonsteady-state chloride migration (NSSCM) test. In addition, based on the concrete finite element models, influences of crack width, crack quantity, and erosion time on chloride migration behaviors and characteristics are studied. Furthermore, a prediction model of chloride concentration on the simulated surface of a rebar in concrete influenced by different crack states is established. This model is used to derive the corrosion current density and corrosion depth prediction models of a rebar in this paper, which can be used by engineers to estimate the migration behaviors of chloride and rebar corrosion degree in RC structures in a short time and evaluate the duration of RC structures after knowing the status of cracks and chloride diffusion sources.

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

Polymers ◽

10.3390/polym10101173 ◽

2018 ◽

Vol 10 (10) ◽

pp. 1173 ◽

Cited By ~ 3

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.

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