scholarly journals Optimization of the Calcium Alginate Capsules for Self-Healing Asphalt

2019 ◽  
Vol 9 (3) ◽  
pp. 468 ◽  
Author(s):  
Shi Xu ◽  
Amir Tabaković ◽  
Xueyan Liu ◽  
Damian Palin ◽  
Erik Schlangen
Keyword(s):  
Calcium Alginate ◽  
Mechanical Response ◽  
Asphalt Mixture ◽  
Environmental Scanning ◽  
Self Healing ◽  
R Ratio ◽  
Capsule Shell ◽  
Alginate Capsules ◽  
Asphalt Mix ◽  
Healing Agent

It has been demonstrated that calcium alginate capsules can be used as an asphalt healing system by pre-placing rejuvenator (healing agent) into the asphalt mix and releasing the rejuvenator on demand (upon cracking). This healing mechanism relies on the properties of capsules which are determined by the capsule preparation process. In this study, to optimize the calcium alginate capsules, capsules are prepared using varying Alginate/Rejuvenator (A/R) ratios. Light microscope microscopy and Environmental Scanning Electron Microscope (ESEM) are employed to characterize the morphology and microstructure of these capsules. Thermal stability and mechanical property are investigated by thermogravimetric analysis (TGA) and compressive tests. The testing results indicate that higher alginate content results in smaller diameter and lower thermal resistance, but higher compressive strength. The optimum A/R ratio of calcium alginate capsules is found to be 30/70. To prove the effectiveness of the optimized capsules, the capsules are embedded in asphalt mortar beams and a bending and healing program is carried out. The effect of capsule shell material on the mechanical response of asphalt mixture is evaluated through three-point bending on the mortar beams embedded with blank capsules (without the healing agent). Aged mortar beams containing alginate capsules encapsulating rejuvenator demonstrate a higher strength recovery after bending tests, which indicates effective healing due to the release of the rejuvenators from the capsules.

scholarly journals Investigation of the Potential Use of Calcium Alginate Capsules for Self-Healing in Porous Asphalt Concrete

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 168 ◽  
Author(s):  
Shi Xu ◽  
Xueyan Liu ◽  
Amir Tabaković ◽  
Erik Schlangen
Keyword(s):  
Asphalt Concrete ◽  
Calcium Alginate ◽  
Self Healing ◽  
Stiffness Modulus ◽  
Porous Asphalt ◽  
Alginate Capsules ◽  
Asphalt Mix ◽  
X Ray Computed ◽  
Indirect Tensile ◽  
Porous Asphalt Concrete

Improving the healing capacity of asphalt is proving to be an effective method to prolong the service life of an asphalt pavement. The calcium alginate capsules encapsulating rejuvenator have been developed and proved to provide successful localized crack healing in asphalt mastic. However, it is not known whether this self-healing asphalt system will improve healing capacity of a full asphalt mix. To this aim, this paper reports on study which investigate effect of the calcium alginate capsules onto self-healing capacity of the porous asphalt mix. X-ray computed tomography (XCT) was used to visualize the distribution of the capsules in porous asphalt. The effect of the capsules on fracture resistance of porous asphalt concrete was studied by semi-circular bending (SCB) tests. A semi-circular bending and healing programme was carried out to evaluate the healing effect of these capsules in porous asphalt concrete. Indirect Tensile Stiffness Modulus (ITSM) tests were employed in order to investigate the influence of the capsules on the stiffness of the porous asphalt concrete. The results indicate that incorporating calcium alginate capsules significantly improve the healing capacity of porous asphalt concrete without compromising its performance.

Modeling of the behaviour of concrete elements containing a self- healing agent

2021 ◽  
Author(s):  
Todor Zhelyazov ◽  
Radan Ivanov
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Mechanical Response ◽  
Numerical Procedure ◽  
Plain Concrete ◽  
General Purpose ◽  
Self Healing ◽  
Structural Element ◽  
Healing Agent ◽  
Concrete Elements

<p>This contribution focuses on the numerical modelling and simulation of the mechanical behaviour of structural elements containing a self-healing agent. Specifically, the finite element modelling of the mechanical response of plain concrete structural element, containing a healing agent and subject to various loading conditions is discussed. A customized numerical procedure designed to implement the Damage Mechanics-based constitutive relation for concrete into a general-purpose finite element code is developed. The procedure comprises algorithms for evaluation of the volume of newly-formed cracks, the recovery of stiffness of the structural element due to crack closure, the initiation of healing and its effect on the overall response of the structural element. The procedure is demonstrated by simulations of a concrete cylinder subjected to compression and torsion.</p>

scholarly journals Technological Features of Production Calcium-Alginate Microcapsules for Self-Healing Asphalt

2018 ◽  
Vol 251 ◽  
pp. 01008 ◽  
Author(s):  
Sergey Inozemtcev ◽  
Evgeniy Korolev
Keyword(s):  
Sodium Alginate ◽  
Calcium Alginate ◽  
Reducing Agent ◽  
Self Healing ◽  
Single Drop ◽  
Alginate Capsules ◽  
Formulation Factors ◽  
Suspension Preparation

The effect of the formulation factors of calcium-alginate suspension preparation on the properties of calcium-alginate microcapsules was studied. The maximum useful volume of the reducing agent is set it was established, up to 93.8% of the total volume, in microcapsules, from the beating, to retain 2.31% sodium alginate and 10.5% reducing agent. The proposed mechanism for the formation of calcium-alginate capsules, which occurs due to shrinkage during the drying of a single drop of suspension, breaking the emulsion and forming an integral shell with a nucleus from the reducing agent.

Thermal and Mechanical Properties of Calcium Alginate Capsules for Self-Healing Asphalt Concrete

2021 ◽  
Vol 1041 ◽  
pp. 101-106
Author(s):  
Sergey Inozemtcev ◽  
Evgeniy Korolev ◽  
Toan Do Trong
Keyword(s):  
Mechanical Properties ◽  
Asphalt Concrete ◽  
Calcium Alginate ◽  
Breaking Load ◽  
Self Healing ◽  
Thermal And Mechanical Properties ◽  
Strength Index ◽  
Alginate Capsules ◽  
Maximum Decrease ◽  
Loss Of Strength

The key physical and mechanical property is the strength of the capsules, which ensure the implementation of the self-healing technology, in which the capsules are not destroyed during the compaction of the asphalt concrete mixture, but are destroyed during the formation of defects in the asphalt concrete. An increase in the content of the reducing agent in the composition of the alginate emulsion leads to a decrease in the breaking load during compression of the capsules, which is explained by an increase in their diameter. But the change in the content of sodium alginate does not have a significant effect on mechanical properties. As a result of exposure to a temperature of 170 °C, a decrease in the strength of the capsules by 22 % after 1 hour of exposure in the burning oven is observed, and with an increase in the time to 4 hours, the strength decreases by 46.9 %. The maximum decrease in the strength index after 4 hours of exposure at a temperature of 160 °C reaches 29.9 %. A decrease in temperature to 150 °C leads to a decrease in the loss of strength. The strength of the capsules decreases by 4 % after 4 hours of exposure at 150 °C. Exposure of capsules to a temperature of 140 °C has no significant effect on strength.

scholarly journals Conductive Compartmented Capsules Encapsulating a Bitumen Rejuvenator

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1361
Author(s):  
Amir Tabaković ◽  
Joseph Mohan ◽  
Aleksandar Karač
Keyword(s):  
Production Process ◽  
Induction Heating ◽  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Thermal Characteristics ◽  
Iron Particle ◽  
Uniaxial Compression Test ◽  
Self Healing ◽  
Healing System ◽  
Alginate Capsules

This paper explores the potential use of conductive alginate capsules encapsulating a bitumen rejuvenator as a new extrinsic self-healing asphalt method. The capsules combine two existing self-healing asphalt technologies: (1) rejuvenator encapsulation and (2) induction heating to create a self-healing system that will provide rapid and effective asphalt pavement repair. The work presents a proof of concept for the encapsulation process, which involves embedding the capsules into the bitumen mortar mixture and the survival rate of the capsules in the asphalt mixture. A drip capsule production process was adopted and scaled up to the production of 20l wet capsules at rate of 0.22 l/min. To prove the effectiveness and its ability to survive asphalt production process, the capsules were prepared and subjected to thermogravimetric analysis (TGA) and uniaxial compression Test (UCT). The test results demonstrated that the capsules had suitable thermal characteristics and mechanical strength to survive the asphalt mixing and compaction process. Scanning electron microscopy (SEM) was employed to investigate physiological properties, such as rejuvenator (oil) and iron particle distribution, within the capsules. The electrical resistance tests proved that the capsules were capable of conducting electrical current. The capsules were also tested for their conductive properties in order to determine whether they are capable of conducting and distributing the heat once subjected to induction heating. The results showed that capsules containing higher amounts of iron (alginate/iron powder in a ratio of 20:80 by weight) can efficiently conduct and distribute heat. To prove its success as an asphalt healing system, conductive alginate capsules encapsulating a bitumen rejuvenator were embedded in a bitumen mortar mix. The samples where then subjected to local damaging and healing events, and the degree of healing was quantified. The research findings indicate that conductive alginate capsules encapsulating a bitumen rejuvenator present a promising new approach for the development of an extrinsic self-healing asphalt pavement systems.

scholarly journals Research on Improving the Durability of Bridge Pavement Using a High-Modulus Asphalt Mixture

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1449
Author(s):  
Wenfeng Wang ◽  
Shaochan Duan ◽  
Haoran Zhu
Keyword(s):  
Construction Industry ◽  
Mechanical Response ◽  
Design Method ◽  
Asphalt Mixture ◽  
Field Tests ◽  
Bottom Layer ◽  
High Modulus ◽  
Practical Applications ◽  
Depth Prediction ◽  
Pavement Structure

In order to improve the durability of the asphalt pavement on a cement concrete bridge, this study investigated the effect of the modulus of the asphalt mixture at the bottom layer on the mechanical response of bridge pavement, along with a type of emerging bridge pavement structure. In addition, the design method and pavement performance of a high-modulus asphalt mixture were investigated using laboratory and field tests, and the life expectancy of the deck pavement structure was predicted based on the rutting deformation. The results showed that the application of a high-modulus asphalt mixture as the bottom asphalt layer decreased the stress level of the pavement structure. The new high-modulus asphalt mixture displayed excellent comprehensive performance, i.e., the dynamic stability reached 9632 times/mm and the fatigue life reached 1.65 million cycles. Based on the rutting depth prediction, using high-modulus mixtures for the bridge pavement prolonged the service life from the original 5 years to 10 years, which significantly enhanced the durability of the pavement structure. These research results could be of potential interest for practical applications in the construction industry.

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