Use of Recycled Plastics in Eco-efficient Concrete

F. Pacheco-Torgal, Jamal Khatib, Francesco Colangelo, Rabin Tuladhar, Fernando Pacheco-Torgal

• Publisher: Woodhead Publishing
• Year: 2018
• Print ISBN: 9780081026762
• eBook ISBN: 9780081027332
• Topic: Technology & Engineering
• Subtopic: Architecture Methods & Materials
• Index: Technology & Engineering

Use of Recycled Plastics in Eco-efficient Concrete looks at the processing of plastic waste, including techniques for separation, the production of plastic aggregates, the production of concrete with recycled plastic as an aggregate or binder, the fresh properties of concrete with plastic aggregates, the shrinkage of concrete with plastic aggregates, the mechanical properties of concrete with plastic aggregates, toughness of concrete with plastic aggregates, modulus of elasticity of concrete with plastic aggregates, durability of concrete with plastic aggregates, concrete plastic waste powder with enhanced neutron radiation shielding, and more, thus making it a valuable reference for academics and industrial researchers.- Describes the main types of recycled plastics that can be applied in concrete manufacturing- Presents, for the first time, state-of-the art knowledge on the properties of conventional concrete with recycled plastics- Discusses the technological challenges for concrete manufactures for mass production of recycled concrete from plastic waste

1

Introduction to the use of recycled plastics in eco-efficient concrete

F. Pacheco-Torgal C-TAC Research Centre, University of Minho, Guimarães, Portugal

Abstract

This chapter addresses several problems associated with waste plastic. Data on plastic production and on waste plastic are reviewed. The unrealistic expectations that have been put on the “miracle” digesting plastic enzyme case are commented upon. The case of Europe, European directives, and targets concerning waste plastic recycling, as well as on the risk of waste smuggling, are addressed. The importance of recycling waste plastics through concrete is emphasized. A book outline is included.

Keywords

Plastics; Recycling targets; Thermoplastics; Thermosetting plastics; Waste

1.1. The waste plastic problem

Deriving from the Greek word ''plastikos'' meaning fit for moulding, plastics comprise mainly two broad categories (thermoplastics and thermosetting plastics). The former include plastics (polyethylene, polypropylene, polysterene, polycarbonates, etc.) that can be heated up to form products and if needed can be reheated and melted again for new forms. In contrast, the latter (polyurethane, polyesters, phenolic and acrylic resins, silicone, etc.) can be melted and formed, but unlike thermoplastics cannot be remelted. The global production of fossil-based plastics has grown more than 20-fold since 1964 to 322 million ton in 2015 ( Wei and Zimmermann, 2017; PlasticsEurope, 2017). Not only the production of plastics consumes yearly 4%–8% of the global crude oil extraction meaning that if plastics are disposed instead of being recycled, these resources are lost but the worst part is that plastic waste is harmful because pigment contains many trace elements that are highly toxic and need hundreds of years to degrade (Huysman et al., 2017). More worrying is the several millions of tons of plastic waste that are entering the ocean each year, for quite some time, whose damaging action has been addressed by several authors (Eriksen et al., 2014; Jambeck et al., 2015; Sussarellu et al., 2016; Green et al., 2016; MacArthur, 2017; Lamb et al., 2018). Between 8 and 24 tons of plastic waste enter oceans each minute (Haward, 2018).

According to ten Brink et al. (2018), the annual cost of marine litter is conservatively estimated at US$ 40 billion. And in July 19, 2017 Science magazine published an article warning that by 2050, we'll have produced 26 billion tons of plastic waste, half of which will be dumped in landfills and the environment (Guglielmi, 2017). It’s then no surprise that target 14.1 of the 2030 Agenda for Sustainable Development seeks to prevent and significantly reduce marine pollution of all kinds, in particular, from land-based activities, including marine debris, by 2025. Yes, it’s true that on 17th of April 2018 a paper published in the Proceeding of the National Academy of Sciences of the United States of America (Austin et al., 2018) reported the discovery of an enzyme that can digest highly crystalline PET and also polyethylene-2,5-furandicarboxylate (PEF). However, as Oliver Jones, analytical chemist at RMIT University in Melbourne, recognized “there is still a way to go before you could recycle large amount of plastic with enzymes” (Gabbatiss, 2018). But a more wise position was made by Adisa Azapagic, at the University of Manchester who mentioned that “A full life-cycle assessment would be needed to ensure the technology does not solve one environmental problem—waste—at the expense of others, including additional greenhouse gas emissions” (Carrington, 2018). And if a lesson can be extracted from this case, it is that scientists should have some lessons on public communication, a problem recognized several years ago (Soapbox Science, 2012; Goldstein, 2012; Grant, 2016). In the meantime a study published on May of 2018 showed that each liter of sea ice on the Arctic contained around 12,000 particles of plastic (La Daana et al., 2018). No wonder then that a previous study (Wilcox et al., 2015) revealed that around 90% of seabirds have plastic waste particles in their gut that they mistakenly took to be fish eggs. Also, Rochman (2018) recently showed that the ocean is not the only place to suffer damaging environmental impacts. Around 26 million tons of plastic waste are generated in Europe every year, which makes Europe the second largest producer of plastic materials, being responsible for 20% of the world production. Packaging applications, the largest application sector, represent 39.6% of the total plastic demand (Huysman et al., 2017). In the past years significant share of European waste plastics leave the EU to be treated in third world countries, where different environmental standards may apply (EUROSTAT, EuropePlastics). However, since January of 2018 China decided to ban the imports of 24 kinds of waste including waste plastic which will aggravate the problem of plastic waste in Europe. And that is why plastic waste is one of the five priority areas in the EU action plan for the circular economy—CE (EC, 2015a). The CE concept may have been inspired by Rachel Carson's Silent Spring and the “limits to growth” thesis of the Club of Rome in the 1970s (Winans et al., 2017) and is being promoted by the EU, but several national governments still argue (Geissdoerfer et al., 2017) that the conceptual relationship between the CE and sustainability is not clear, having detrimental implications for the advancement of sustainability science. Others (Korhonen et al., 2018) mentioned that the CE practice has almost exclusively been developed and led by practitioners, that is, policy-makers, businesses, business consultants, business associations, and business foundations and as a result the research content of the CE concept is superficial and unorganized.

Still in the European Union context, looking into the past is worth remembering that the previous Directive 94/62/EC had imposed a recycling target which required 22.5% of waste plastic packaging to be recycled. This target increased toward 55% by 2030 (EC, 2015b) but on March 14 of the 2017 the European Parliament voted for legislation to aim for a recycling rate target of 70% by 2030, with a proposed 80% target for packaging materials—including paper, cardboard, plastics, glass, metal, and wood. This constitutes a high ambition postured by the EU and there is still some controversy regarding job creation in the field of waste recycling. While the report cited by the European Parliament mentioned the possibility of creation of 1–3 million jobs (IP, 2017) the fact is that the European Commission has presented a much lower number of just 170,000 direct jobs (Politico, 2018). Most of these optimistic projections usually tend to forget that as Cooper and Gutowski (2017) recently pointed the fact that reusing a product does not guarantee an environmental benefit because of the need to upgrade old product efficiencies and the fact that more efficient new products can be on the market. For instance, as contradicting as it may seem, Dunant et al. (2018) showed that reused steel is somewhat more expensive than new steel elements. Fig 1.1 shows plastic post-consumer waste rates of recycling, energy recovery, and landfill per country in 2016 and also the group of 10 countries that have implemented landfill restrictions. The figure illustrates in a very clear way the effort that needs to be taken to close the gap between the state-of-the-art plastic waste recycling and the new recycling targets. Of course energy recovery is nothing more than incineration (Eriksson and Finnveden, 2017).

Also the proof that the new and ambitious waste plastic recycling approved by the European Parliament could be hard to achieve is given by Karl-H. Foerster, executive director of industry organization Plastics Europe, who responded to the parliamentary proposals, saying that: “Taking into account today's recycling technology, we already consider that the 55% plastics packaging preparing for re-use and recycling target proposed by the Commission is challenging. We would therefore like to call on the Presidency of the Council to carefully assess the impact prior to adopting any substantive amendment to the rules on the calculation initially proposed by the Commission.” That position however must be seen in the light of the interests of the associates of Plastics Europe which are in the business of plastic manufacture and not in the business of waste plastic recycling. Of course, some European countries like the Netherlands, which in 2014 already recycled 50% of (packaging) plastics, aiming for 52% in 2022 (Gradus et al., 2017) will be in a better posit...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of contributors
• 1. Introduction to the use of recycled plastics in eco-efficient concrete
• 2. Techniques for separation of plastic wastes
• 3. Hydraulic separation of plastic wastes
• 4. Production of recycled polypropylene (PP) fibers from industrial plastic waste through melt spinning process
• 5. Fresh properties of concrete containing plastic aggregate
• 6. Mechanical strength of concrete with PVC aggregates
• 7. Characteristics of concrete containing EPS
• 8. Lightweight concrete with polyolefins as aggregates
• 9. Properties of concrete with plastic polypropylene aggregates
• 10. Virgin and waste polymer incorporated concrete mixes for enhanced neutron radiation shielding characteristics
• 11. Performance of dioctyl terephthalate concrete
• 12. Recycling of PET in asphalt concrete
• 13. Recycling of different plastics in asphalt concrete
• 14. Replacement of stabilizers by recycling plastic in asphalt concrete
• 15. The use of recycled plastic as partial replacement of bitumen in asphalt concrete
• 16. Concrete reinforced with metalized plastic waste fibers
• 17. Performance of concrete with PVC fibres
• 18. Recycled waste PET for sustainable fiber-reinforced concrete
• 19. Properties of recycled carpet fiber reinforced concrete
• 20. Performance of asphalt concrete with plastic fibres
• 21. Sustainability of using recycled plastic fiber in concrete
• Index