Investigating the effect of temperature on self-healing properties of neat and polymer-modified bituminous binders

Ionomers are a class of polymers which contain a small fraction of charged groups in the polymer backbone. These ionic groups aggregate (termed ionic aggregates) to form temporary cross-links that break apart over the ionic dissociation temperature and re-aggregate on cooling, influencing the mechanical properties of these polymers. In addition to enhanced mechanical properties, some ionomers also exhibit self-healing behavior. The self-healing behavior is a consequence of weakly bonded ionic aggregates breaking apart and re-aggregating after puncture or a ballistic impact. The structure and properties of ionomers have been studied over the last several decades; however, there is a lack of understanding of the influence of an electrostatic field on ionic aggregate morphology. Characterizing the effect of temperature and electric field on the formation and structure of these ionic aggregates will lead to preparation of ionomers with enhanced structural properties. This work focuses on Surlyn 8940 which a poly-ethylene methacryclic acid co-polymer in which a fraction of the carboxylic acid is terminated by sodium. In this work, Surlyn is thermoelectrically processed over its ionic dissociation temperature in the presence of a strong electrostatic field. Thermal studies are performed on the ionomer to study the effect of the thermoelectric processing. It is shown that the application of a thermoelectric field leads to increase in the ionic aggregate order in these materials and reduction in crystal size distribution. Thermal Analysis is performed using a Differential Scanning Calorimeter and the resulting thermogram analysis shows that thermoelectric processing increases the peak temperature and onset temperature of melting by 4 C and 20 C respectively. The peak width at half maximum of the melting endotherm is reduced by 10 C due to thermoelectric processing. This serves as a measure of the increased crystallinity. A parametric study on the effect of field duration and field strength is also performed.

Download Full-text

Creep Properties and Constitutive Model of Salt Rock

Advances in Civil Engineering ◽

10.1155/2021/8867673 ◽

2021 ◽

Vol 2021 ◽

pp. 1-29

Author(s):

Qiang Zhang ◽

Zhanping Song ◽

Junbao Wang ◽

Yuwei Zhang ◽

Tong Wang

Keyword(s):

Mechanical Properties ◽

Constitutive Model ◽

Effect Of Temperature ◽

Creep Process ◽

Underground Storage ◽

Self Healing ◽

Salt Rock ◽

Creep Properties ◽

Term Operation ◽

Rock Creep

Due to the advantages of low porosity, low permeability, high ductility, and excellent capacities for creep and damage self-healing, salt rock is internationally considered as the ideal medium for underground storage of energy and disposal of radioactive waste. As one of the most important mechanical properties of salt rock, creep properties are closely related to the long-term operation stability and safety of salt rock underground storage cavern. A comprehensive review on the creep properties and constitutive model of salt rock is put forward in this paper. The opinions and suggestions on the research priority and direction of salt rock's mechanical properties in the future are put forward: (1) permeability variation of salt rock under the coupling effect of temperature and stress; (2) damage mechanism and evolution process under the effect of creep-fatigue interaction and low frequency cyclic loading; (3) microdeformation mechanisms of salt rock and the relationship between microstructure variations and macrocreep behavior during creep process; (4) the establishment of the creep damage constitutive model with simple form, less parameters, easy application, and considering the damage self-healing ability of salt rock simultaneously.

Download Full-text

Analysis of Fatigue and Healing Properties of Conventional Bitumen and Bio-Binder for Road Pavements

Materials ◽

10.3390/ma13020420 ◽

2020 ◽

Vol 13 (2) ◽

pp. 420 ◽

Cited By ~ 1

Author(s):

Elena Gaudenzi ◽

Fabrizio Cardone ◽

Xiaohu Lu ◽

Francesco Canestrari

Keyword(s):

Experimental Approach ◽

Fatigue Behavior ◽

Self Healing ◽

Aged Condition ◽

Temperature Dependent ◽

Modified Bitumen ◽

Complex Issue ◽

Rheological Measurements ◽

Bio Oil ◽

Bituminous Binders

The analysis of fatigue behavior of bituminous binders is a complex issue due to several time-temperature dependent phenomena which interact simultaneously, such as damage accumulation, viscoelasticity, thixotropy, and healing. The present research involves rheological measurements aimed at evaluating the fatigue behavior and compares the self-healing capability of two plain bitumen and a bio-binder obtained by partially replacing one of the plain bitumen with a renewable bio-oil. Healing potential was assessed by means of an experimental approach previously implemented for modified bitumen and bituminous mastic and based on the use of a dynamic shear rheometer (DSR). The effects of some variables such as bitumen type, bio-oil addition, and aging on the healing potential of binders were taken into account. Results showed that the above-mentioned method for healing analysis is also suitable for conventional and bio-add binders. Outcomes of the experimental investigation highlight that fatigue and self-healing are mainly dependent on binder consistency and also affected by aging. Finally, the addition of bio-oil may induce even better performances in terms of healing potential compared to conventional bitumen, especially in aged condition.

Download Full-text

The effect of temperature on bacterial self-healing processes in building materials

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/726/1/012012 ◽

2020 ◽

Vol 726 ◽

pp. 012012

Author(s):

P Ryparová ◽

P Tesárek ◽

H Schreiberová ◽

Z Prošek

Keyword(s):

Building Materials ◽

Effect Of Temperature ◽

Self Healing ◽

Healing Processes

Download Full-text

Modification of bituminous binders for guss asphalt

E3S Web of Conferences ◽

10.1051/e3sconf/202127402011 ◽

2021 ◽

Vol 274 ◽

pp. 02011

Author(s):

Marina Vysotskaya ◽

Anastasia Kurlykina ◽

Artem Shiryaev ◽

Anna Tkacheva ◽

Dmitry Litovchenko

Keyword(s):

Asphalt Concrete ◽

Raw Material ◽

Structural Defects ◽

Concrete Pavements ◽

Self Healing ◽

Modified Bitumen ◽

Concrete Mixtures ◽

Bridge Structures ◽

Bituminous Binders ◽

Thermal Stability Of

Over the past few years, the research of the use of cast asphalt concrete mixtures in the upper layers of the coating of bridge structures has been actively carried out. The experience gained allows us to conclude that one of the most common effective ways to improve the durability and thermal stability of cast asphalt concrete pavements is the use of modified bituminous binders. The modified bitumen part of cast asphalt concrete acts as a medium capable of initiating the «self-healing» of the composite, independently eliminating structural defects. This study aims to research the rheological characteristics of modified bituminous binders. Bitumen grade BND 50/70 was used as a raw material in the study; the following types of additives were used as its modifiers: rubber modifier (RM), EVATHERM and SBS. The optimal concentrations of the proposed additives for modification allowing to achieve the effect of structuring the mastic component of cast asphalt concrete with insignificant increases in the temperatures of mixing and compaction of mixtures based on them have been revealed.

Download Full-text

Microencapsulated healing agents for an elevated-temperature cured epoxy: Influence of viscosity on healing efficiency

Polymers and Polymer Composites ◽

10.1177/09673911211045373 ◽

2021 ◽

pp. 096739112110453

Author(s):

Habibah Ghazali ◽

Lin Ye ◽

Amie N Amir

Keyword(s):

Fracture Toughness ◽

Elevated Temperature ◽

High Performance ◽

Healing Process ◽

Polymer Network ◽

Diglycidyl Ether ◽

The Self ◽

Effect Of Temperature ◽

Mode I ◽

Self Healing

Among many applications, elevated-temperature cured epoxy resins are widely used for high-performance applications especially for structural adhesive and as a matrix for structural composites. This is due to their superior chemical and mechanical properties. The thermosetting nature of epoxy produces a highly cross-linked polymer network during the curing process where the resulting material exhibited excellent properties. However, due to this cross-linked molecular structure, epoxies are also known to be brittle, and once a crack initiated in the material, it is difficult to arrest the crack propagation. Earlier research found that the inclusion of encapsulated healing agents is able to introduce self-healing ability to the room-temperature cured epoxies. The current study investigated the self-healing behaviour of an elevated-temperature cured epoxy, which incorporated the dual-capsule system loaded with diglycidyl-ether of bisphenol-A (DGEBA) resin and mercaptan. The microcapsules were prepared by the in-situ polymerisation method while the fracture toughness and the self-healing capability of the tapered-double-cantilever-beam (TDCB) epoxy specimens were measured under Mode-I fracture toughness testing. We investigated the effect of temperature on viscosity of the healing agents and how these values influence the formation of uniform healing on the fracture surfaces. It was found that incorporation of the dual-capsule self-healing system onto an elevated-temperature cured epoxy slightly changed the fracture toughness of the epoxy as indicated by the Mode-I testing. In the case of thermal healing at 70°C, the self-healing epoxy exhibited a recovery of up to 111% of its original fracture toughness, where a uniform spreading of the healant was observed. The excellent healing behaviour is attributed to the lower viscosity of the healant at higher temperature and the higher glass transition temperature ( Tg) of the produced healant film. The DSC analysis confirmed that the healing process was not contributed by the post-curing of the host epoxy.

Download Full-text