Practicability Use of Epoxy Coated Rebar and Crack Control - Research Paper Example

Performance Practicality of Epoxy-Coated Reinforcement and Crack Control for Varying Specimen Size: A Laboratory Analysis

Project Summary

With the continued growth of the planet's population, the need for expanding cities and more extensive infrastructure to sustain this population growth is drastic. These cities and infrastructure now need to withstand higher forces and require a greater life expectancy. Therefore, a more resistant and sturdier reinforcement for concrete members/structures need to be implemented. The epoxy-coated reinforcement was tested for its corrosion resistance and its effects on the structural concrete itself in terms of crack control and contrasted to traditional techniques such as black rebar and galvanized rebar. The successful application of epoxy-coated reinforcement will increase the shelf life and resistance of concrete structures.

Keywords

Fracture-Restraint, Thermosetting Resin Epoxy, Epoxy Covered Rebar, Crack Dimensions

INTRODUCTION

1.1 Background of the Study

In recent years, North America and in particular the united states and Canada, predominantly, have adopted a new steel reinforcement coating strategy using epoxy to reduce the effects of stress corrosion cracking within concrete (Weishaar et al., 2018). This has come into effect as studies have shown that corrosion cracking accounts for 25-30% of infrastructural damage caused by poor corrosion techniques used in the structural concrete industry in the past 50 years (karaxi, kartsonakis & charitidis, 2019). The main suspect of corrosion in steel reinforcement is directly proportional to the chloride quantity found in the process of corrosion itself and the dimensional area of fracture (keßler et al., 2015). Moreover, recent theoretical developments have instigated methods to utilize epoxy-coated steel reinforcements for concrete fabrication within offshore and aquatic environments as these areas, in particular, are more susceptible to corrosion due to the presence of waves (Assaad and Issa, 2012). According to Assaad and Issa (2012), the location of the concrete in these environments undertakes a recurring washing and drying technique, which consequently causes confined chloride amassing that would further pierce through the open capillaries and expedite corrosion. Thus, the cross-section of the steel reinforcement is weakened as a result of chloride corrosion leading to deteriorating the overall structural forces in the bearing capacity of the concrete.

Statement of the Problem

Epoxy in its unadulterated form is ineffective in substantial protection of the rebar resin as it would decrease the adhesive stability between concrete and the coated steel reinforcement (pour-Ali, dehghanian & kosari, 2015). Although self-healing polymer advantageously offers properties named by having a corrosion-resistant nature, electrical conductivity, enhanced chemical and other mechanical capabilities enhances structural serviceability. Thus, a newly introduced method in conducting polymers such as self-healing polyaniline lignosulfonate (pani-lgs) can be incorporated with epoxy coating in steel rebar inside microcapsules of the non-conducting concrete matrix to eradicate any crack formations in future structures (Gupta et al., 2013).

Significance of the Study

The research would benefit the society, economy, and environment overall since it would provide a chance to protect future structures against obscured damage which may incur costly maintenance overtime around if not thoroughly studied. On the same note, the research is based upon the practicality features of epoxy-coated steel reinforcement on crack control given the necessity for testing on varying specimen dimensions to lessen the effects of corrosion. Notably, a study conducted by Weishaar et al. (2018) shows that globally $276 billion is lost every year due to the unidentified corrosion within steel reinforcements. Equally, Research by Gardner et al. (2018) supports the claims made by the disturbance of almost 60% of the respondents in public traffic and general environment due to maintenance of poorly coated steel reinforcements in infrastructure (see fig. 1). Also, monitoring of such construction work would most likely affect the health and safety concerns of pedestrians and labourers alike.

Figure 1: surveyed respondents highlight the result of maintenance due to maintenance of uncoated steel bars. Adapted from (Gardner et al., 2018, p. 241, fig. 5)

1.2 Aim of the Study

The overarching aim of this study is to evaluate the prototype workability for epoxy-coated reinforcements on tackling crack control for varying sized specimen samples.

1.3 Study Objectives

• To prepare a regulated coating mixture of epoxy with regulated enhancement properties of polymers.
• To create varying specimen sample sizes as a prototype concerning various structural models of which such epoxy-coated reinforcements would be used for such as marine bridges, pavements, and stairs.
• To simulate a proper environmental condition (60℃) to cure the concrete for 12 hours and apply the coating.
• To analyze the issues involved with corrosion in comparison with specimen samples.
• To identify crack formation area due to corrosion with related structural samples, to which a recommended approach will be justified through laboratory analysis and repetitions.

LITERATURE REVIEW

Conceptual Framework

The application of epoxy-coated steel rebar occurs as fundamental due to its nature of environmentally friendly. Hence, it serves as opposed to carcinogenic additives like chromates, which are used on steel and aluminium alloys (Gupta et al., 2013). Henceforth, studies determined that environmental impacts of the combination of epoxy and polymers, which are derived from sustainably sourced organic compounds. As per Capricho, Fox and Hameed (2019), they require significant enthalpies and performed well under high temperatures, while reducing CO2 emissions. This research study assists in the delivery of successful functionality of infrastructures considering the utilization of self-healing agents within epoxy polymerization in varying sized specimens.

Review of Related Literature

Moreover, few studies have focused on the relatable specimen sizes for specific infrastructural usage concerning epoxy-coated steel on the effect of fracture. The gap has been presented from Angst (2018), who denoted that the application of uncoated steel reinforcements had been tested under the duration of time taken for corrosion to occur within 28 days, which resulted in poor results as expansive swelling within the concrete core had not explicitly been recorded in terms of 3% precipitation causation of chloride formation nor given varying identifiable sizes of modelling serviceability. The specimen size in this experiment is a critical factor for improper testing, which had only considered a concrete surface area of 2 m2 (Angst, 2018). Another study by Weishaar et al. (2018), describes the potential advantages in the usage of epoxy with self-healing polymer additives for coating steel rebar, which concentrated on the wall thickness coating of 10 wt% in comparison with 0 wt% on only pre-corroded specimen samples. The results from Weishaar et al. (2018) evaluated the load-bearing capacity on specimen samples given an area of 51.61 cm2 concerning the thickness of the coating. They had shown significant results in reasonably slowing down corrosion rates in turn. The gap in both studies failed to address the need for sizable specimen samples to dictate the effectiveness of epoxy-polymer coating for different structural operations.

METHODOLOGY

Introduction

The steel reinforcement coating strategy using epoxy aims at reducing the effects of stress corrosion cracking within concrete (Weishaar et al., 2018) needs the execution of the methods with a suitable design of the protocol, most of which are either consisting of the principle of mechanical or the electrochemical strategies. The methodology of the steel reinforcement is based on the reinforcement of the bars, which are mostly either soft organic materials or hard inorganic metallic substances. The soft organic materials used are the use of epoxy coatings, whereas the metallic coatings include use of metals, like zinc, stainless steel to name a few, which can save the steel by virtue of their sacrificial activity towards the corrosion, which is usually more than iron (zheludkevich et al., 2012). In response, the national bureau of standards (now the national institute for standards & technology), a survey was tried, where the ability of various liquids and the powder material was under investigation concerning their ability against the corrosion, where the epoxy coating was found to be best in the reinforcing of steel under its durability as well as the permeability towards the chloride.

Procedure

Therefore, the methodology of the epoxy-based steel reinforcement is based on the number of protocols, like, preparation of surfaces, heating followed by powder application. In the preparation step, the reinforcing bars are subjected to neat cleaning to finally provide a roughen area to anchor the adhesion surface (Zhao & Jin 2016). The next heating step is associated with the heating of such bars up to 230 degree Celsius. This is followed by the transport of this heated steel through a chamber where the powders of epoxy materials are continuously sprayed.

This adhesion of the epoxy materials on the heated bars lead to the formation of a complex, which provides the desired properties to the reinforcing bars through the formation of a cross-linked polymer through the reaction between the epoxy powder and the reinforcing bars. The method of epoxy coating is finished at the last step of cutting, where the rapid decrement of the temperature happens of the reinforcing bar through the exposure of the bars towards either air or the water. Need to mention that the duration of curing is approximately thirty seconds only, which is enough time tom make the materials up to its desired state. A comparison of the bar before and after reinforcing is given by McDonald et al. in 2010 (McDonald et al., 2010).

Figure 2. Comparison of the reinforced bar before and after. Adapted by (McDonald et al., 2010, p 5, fig. 1)

Therefore, it needs a field experiment for the reinforcement of the steels, as mentioned in the above section. In contrast, the lab experiment is not that much effective in this case, since the site and status of the infrastructure are crucial before starting of the methodological design, and hence the field investigation is essential. Vernier calliper instrument is useful in this case, which would give the change in the diameter of the bar according to the desired level of the coating of the bars. Not to mention, before the fieldwork, it is necessary to interview the local people having technical engineering background to get to know about the alteration of the deformation status of the infrastructure over time, where an idea might be generated about the state of the deformation. The comparison of the hardness of various materials before and after the epoxy coating might be beneficial by means of the literature search, which (rigidity) is one of the crucial variables of the work (Tylek et al., 2014). Before starting the project, a case study on a prototype infrastructure might also be beneficial, as it will provide some sort of idea about the outcome of the work by means of comparison of the materials being used as well as comparison of the hardness data.

ANALYSES AND FINDINGS

Dissemination of Findings

A central part of the research is the dissemination of the research findings, the ability to spread the results to the largest possible audience is essential to the primary objective of furthering the development and research of the topics. Dissemination plans can be severely impacted by numerous factors such as time, budget, public perception and skill. Thus, the mentioned factors must be taken into account to ensure successful dissemination. The goal is not just to reach the largest possible audience but maybe as important you must reach the intended audience like the scientific community and the politicians, policymakers, practitioners and the public known as the informal community.

Informal Community

When reaching to the informal community of politicians, policymakers and the like, the objective is to mould and tailor-make the research results to communicate successfully to these specific groups. The aim is to have the research findings factor into the decisions and work of the informal community. We will pursue two different methods to reach this community with the results of our research, they are co-ordinated press releases and sponsored partnerships with various YouTube channels. For the press releases, the information from the study will be summarised and submitted to a renowned and well-connected public relations company in this case we have chosen Edelman Australia Pty Ltd. They will be tasked with the distribution of the press release to various forms of media such as newspapers, blogs, LinkedIn and magazines such as structure magazine and concrete construction magazine. The research team will be required to develop an adequate summary and co-ordinate with the company to ensure a seamless release.

The primary method of dissemination of information to the informal community will be through popular and high traffic science-based youtube channels. Three (3) possible channels were identified for this partnership, and they are:

Smartereveryday with 8.07 million subscribers, 750 million views and individual video views ranging from 500 thousand to 78 million.

Veritasium with 7.04 million subscribers, 790 million views and individual video views ranging from 500 thousand to 45 million.

Kurzgesagt with 11.9 million subscribers, 975 million views and individual video views ranging from 1 million to 25 million.

All 3 YouTube channels are science-based and highly informative and have been used to promote research and topics in the past. Based on the YouTube channels watch statistics, it was decided to partner with Kurzgesagt and Smartereveryday as Veritasium had the lowest views per video and their subscribers overlapped with the other two channels.

Smartereveryday is a channel run by an engineer who creates tailored videos with the express purpose of informing the audience on a specific concept while also being entertaining and relating it to everyday life. He has covered fundamental physics to intricate components of space shuttles. We can expect between 1-4 million views across YouTube and other social media with this partnership.

Kurzgesagt is a channel run by a small group of eager researchers who tailor-make 1 video a month where they use fun and exciting animation and to "make science look beautiful'. They have covered topics ranging from wormholes to the coronavirus pandemic, and we can expect between 3-5 million views across YouTube and other social media with this partnership. The budget allocated for the informal community is $5000.00 with a $1500.00 given to each YouTube channel and $2000.00 for Edelman Australia Pty Ltd.

Scientific community

For the dissemination of the research findings, the primary method is producing a research article and publishing it to composite structures journal on Elsevier, which is a world-renowned scientific journal publisher. Composite structures is an internationally acclaimed journal with a cite score of 5.39 and an impact factor of 4.829. These scores represent the average number of citations received per article published in the journal, and the average number of citations articles published in this journal receive each year, respectively. The creation of this research article will take a considerable amount of time to produce an article of exceptional quality. The publisher has a fee of $4000.00 to publish with them, but this fee covers the article being posted to the subscribers and the public with permission of reuse.

A proposed secondary strategy to ensure the findings reach the entire scientific community was to present the results at the 3rd international conference on concrete sustainability (fib iccs20) held in Prague on the 8th to the 10th of September, 2021. This conference is the world’s premier concrete structure conference with an impact factor of 5.132.

To attend this conference and present the article, the application must be submitted before the 15th of January, 2021, and the article for the oral presentation cannot be more significant than eight pages in length. This would require at least two members of the team to fly to Prague, Czech Republic, to present the findings and this will need to be budgeted for at roughly $5500.00.

The total dissemination of information budget to cover the informal and scientific communities is roughly $14,500.00.

Estimated project timeline

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