Determining the Feasibility of a Circular Economy for Plastic Waste from the Construction Sector in New Zealand
To cite this article: T-A Berry et al 2022 IOP Conf. Ser.: Earth Environ. Sci. 1122 012002
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Determining the Feasibility of a Circular Economy for Plastic Waste from the Construction Sector in New Zealand
T-A Berry1, J K Low2, S L Wallis2, L Kestle3, A Day4 and G Hernandez2.
1Associate Professor, School of Construction and Engineering and Director, Environmental Solutions Research Centre (ESRC), New Zealand.
2Research Associate, ESRC, New Zealand.
3Associate Professor, School of Construction and Engineering, New Zealand
4Project manager, Naylor Love, Auckland, New Zealand E-mail: [email protected]
Abstract. By 2012, the annual quantity of C&D waste produced by 40 countries had reached three billion tonnes, contributing 10-50% to total municipal solid waste around the world. Recent data from Australia and New Zealand estimated a combined contribution of approximately 28 million tonnes C&D waste to landfill for just 0.4% of the world’s population. If C&D waste was produced at an equal rate around the world, global production could be close to seven billion tonnes. In 2015, the global production of plastic waste from building and construction was 13 million tonnes. It is estimated that annually, C&D waste contributes ≥25,000 tonnes to the total amount of plastic landfilled in one major city (Auckland) alone. Waste audits from four sites demonstrated that this was predominantly polyethylene (PE) or polyvinyl chloride (PVC), and was derived from packaging, building componentry and building protection equally. The aims of this study were to implement a
‘foundations to completion’ plastic waste audit on a new secondary school in Auckland, New Zealand. This sheds light on the nature of the plastic waste, e.g., type, use and potential for recyclability or reuse. The aim was to also identify the challenges in the construction industry that hinder effective waste diversion from landfill, and to trial practical on-site solutions.
1. Introduction
On March 2nd 2022, Heads of State, Ministers of Environment and other representatives from 175 nations met in Nairobi to endorse a historic resolution at the UN Environment Assembly (UNEA-5). This forged an international legally binding agreement to End Plastic Pollution by 2024, which addressed the full lifecycle of plastic, including its production, design and disposal1. In particular, this encouraged enhanced international collaboration, promotion of sustainable design for circularity, and recognition of the important role of plastics in society. However, enabling and incentivizing key industry and commercial sectors to manage plastic waste production was not included and therefore a number of major contributors to plastic waste were not addressed.
New Zealand has a land area of 268,021 km² and a population of 5.084 million (2020). New Zealanders dispose of 308kT of plastics per year to landfill2. Of the waste that reaches landfill, approximately 40% is derived from the construction and demolition industry (C&D)3. For Auckland alone (population 1.66 million), it was estimated that at least 25kT of plastic waste was generated by the C&D industry4. This was calculated using an estimated 1.6 million tonnes of waste to landfill in the Auckland region5; of which 4%
of all landfilled waste is predicted to be plastic6. A recent plastic waste study conducted on four commercial construction sites in Auckland identified that polyethylene (PE) was the dominant form of waste, accounting for 77% by mass (82% by volume), while polyvinyl chloride (PVC) was the second most common form, comprising 19% by mass (14% by volume) of plastic waste analysed4. For a single sector that produces such large quantities of waste, including plastics, why is there a lack of any significant focus on waste management?
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There is a lack of knowledge about construction waste, which is one of the main barriers to its diversion away from landfill sites7. Studies investigating a selection of the conscious decisions behind why contractors do not segregate construction waste revealed factors such as management effort required, site space limitations, labour, cost and interference with day-to-day construction activities were the main drivers8,9. Other contributing factors may include lack of access to recycling facilities, industry culture, lack of education and financial incentives8,10 as well as financial and logistical risks and uncertainties8. Table 1 shows construction waste charges for disposal from a selection of countries, where in general higher recycling rates appear to coincide with higher charges. By 2024, in New Zealand, the waste levy charges for landfill classes 1-4 including C&D waste (class 2) will increase to 60 NZD/tonne11. However better incentivisation alone is unlikely to provide the solution to a circular waste economy for this sector which requires further enabling via education, processes and practical onsite solutions.
Table 1. Global snapshot of construction waste recycling success and respective waste disposal charges Country/Region Construction waste charges
Cost (NZD per tonne) **
Current recycling rates (% C&D waste)
Year achieved
Beijing, China12
CDW landfill discharge fee 0.7-1.1
<3% 2014
Shanghai, China12 20% 2014
NZ11 Waste levy (only applies to Class
1 (municipal landfill) 10 28% 2008
Hong Kong13,14 Non-inert C&D waste at landfills Inert waste
23
5.07 92% 2019
Belgium15, 16 General landfill (Flemish
Region) 87 95% 2016
Denmark17, 18 MSW landfill tax 101 (2010) > 80% 1999
UK19 Waste levy, aggregate charge,
large construction site charge 193 94% 2010-2018
Australia20,21,22 General Landfill Levy 96 - 213 67% Nationwide* 2016-2017
Taiwan23 NA NA 54% MSW
recovered 2018 Note: *high regional variations e.g., South Australia and Victoria achieved 90% and 82% recycling rates
respectively before 2020. **Currencies converted on 9th March 2022 (XE.com/Currency converter).
The aims of this study were to implement a ‘foundations to completion’ plastic waste audit on a new secondary school in Central Auckland, New Zealand. This identified the nature of the plastic waste, for example, type, use and potential for recyclability or reuse and also sought to identify the many challenges to the construction industry that currently hinder effective waste diversion from landfill.
2. Methodology 2.1 Site Location
The school redevelopment project was located in central Auckland and involved the construction of a new gym (2100m2) and teaching block (2700m2, with >18 classroom spaces) constructed of a block/concrete
structure, curtain wall exterior façade and a warm roof. The interior fitout was typical to any new school technical classroom and gym build. Construction commenced in the last quarter of 2020 and is forecast to be completed by the fourth quarter of 2022. The project is being delivered on behalf of the Ministry of Education of New Zealand with an estimated project value of $26 million. The partner construction company is the largest privately-owned construction company in New Zealand, specializing in vertical construction including industrial, retail, education, commercial and residential buildings.
2.2 Waste Audit
Plastic waste from the construction of the two new school buildings was separated on-site into a 9m3 skip by a partner construction company, then audited off-site by researchers. A total of three audits were conducted at the end of each of the stages of construction (described in section 2.4)
Plastics of the same (observable) material were sorted into groups (by sight). Each group was labelled, weighed, and a small sample taken to identify the polymer type (using FT-IR ATR analysis). Construction stage and material sources were recorded to investigate the evolution of plastic wastes generated. Whilst volume is an important and commonly reported statistic for C&D waste (due to implications on waste disposal costs), mass is also an important measure as it quantifies waste independent of compactness7. Relative waste compositions as shown have been calculated in terms of mass, unless described otherwise.
Some waste could not be audited due to poor on-site separation which created health and safety issues;
approximately 225kg of plastic waste could not be audited. However, on visual inspection, these plastic types were representative of those audited. This was also due to the lack of site access during a succession of COVID lockdowns in Auckland which prevented researchers from working closely with site staff.
2.3 Lab Analysis
Samples of each type of plastic material were characterized via Fourier Transform Infrared (FTIR) spectroscopy, using a ThermoFisher Nicolet iS50R spectrophotometer in the attenuated total reflectance (ATR) mode equipped with a diamond ATR crystal. The spectra of the samples were recorded as an average of 32 scans. From these spectra, the plastic polymers were determined. Plastic polymers identified by FTIR analysis were PVC, PE, polycarbonate (PC), PVC with calcium carbonate (CaCO3) filler, polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), ethylene/propylene copolymer (EPC), ethylene/vinyl acetate copolymer (EVC) and ‘Other’ plastics which each made up a small proportion of total mass. 74% of samples were identified and assigned to a known polymer with greater than 85% match;
however, some polymers identified did not reach this 85% standard. This was due to their composition being a mix of polymers and contamination of other materials (78% of ‘Other’ plastics, 25% PC, 12% PE, 20%
PET and 3.6% PP).
2.4 Construction Stages & Plastic Use Classification
The following construction stages have been identified for this study: Stage one – Foundations and Structure, Stage two - Exterior Façade and Roofing and Stage three – Interior Fitout.
In order to categorise the plastic waste materials, the following plastic use classifications have been determined for this study (including the small fraction (0.2% by mass) of non-identifiable plastic wastes which were classed as ‘Misc’)
x Building protection, (BP) (e.g. shrink-wrap carpet protectors; also includes tools used during construction, for example latex gloves, reo bar caps)
x Product packaging, (P) (for example, cling film wrap, timber pack wrap and sealant tubes)
x Construction components, (CC) (for example. PVC pipe offcuts, damp proof membranes, bar chairs)
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3. Results and Discussion 3.1 Plastic Waste Quantity
A total of 769kg of plastic waste was produced across the three stages. From the audited mass of 544kg, 71.5% came from Stage Three, followed by 19.0% from Stage One, and 9.5% from Stage Two (Figure 1).
The final stage generated large masses of waste due to excess materials being discarded, such as offcuts and unused construction components.
Figure 1. Plastic mass per construction stage and contribution from Building Protection (BP), Product Packaging (P) and Construction Components (CC)
3.2 Plastic Waste Sources
CC made up the majority of total plastics audited (67.6% by mass), followed by P (25.7%) then BP (6.5%).
By total volume, CC and P contributed similar amounts (45.9% and 41.9%, respectively) while BP made up 12.0%. Based on previous auditing research by the team, it was expected that the packaging component would not dominate the plastic waste source (in contrast New Zealand’s current focus on packaging from the domestic waste sector)4,24. However, this highlights the importance of the adoption of take back schemes for offcuts and surplus from suppliers.
The mass of plastics used for packaging (P) was relatively similar for each construction stage (58.2 kg, 44.5 kg and 35.8 kg respectively for Stages One, Two and Three). Plastics used for BP were mostly generated in Stages One (8.9 kg – 24.3%) and Three (27.2 kg – 73.8%), while CC were disproportionately generated in Stage Three (326 kg – 88.6%), followed by Stage One (35.6 kg – 9.7%). It is important to note the impact of the generation of offcuts and surplus plastic wastes from the final stage of building construction which should inform future site education/practice especially for sub-contractors. In this instance, 140kg of new vinyl flooring was disposed of into the skip at the end of the fixtures and fittings by a sub-contractor. In a previous study in New Zealand, researchers noted that the value of building materials as future resources needs to be recognised and that the lack of training and education, lack of incentives and insufficient logistics (for effective waste separation) still present significant barriers to certain waste management practices26.
3.3 Plastic Polymer Types
PVC made up the largest percentage of waste audited (by mass), followed by PE, PC, PVC + CaCO3 filler, and PP (Table 2). The large mass of PVC in Stage Three was due to vinyl flooring offcuts and a previously mentioned unused roll (construction components) whereas the majority of PE, PP, PET and EPC came from product packaging. Most of the PC was from construction components (for example, offcuts from Stage Three), as well as PVC + CaCO3 filler components (all PVC pipes) and ethylene/vinyl acetate copolymers (all waterproofing membrane offcuts). Building protection products were mostly made from PE (safety mesh fencing) and PP.
Table 2. Plastic mass (kg) of polymer types and percentage of total polymer mass per construction stage.
Polymer type
Stage PVC PE PC PVC +
CaCO3
PP Other PS PET EPC EVC Total
(kg)
1 0.05
(0.1%)
29.93 (29%)
- 12.95
(13%)
22.95 (22%)
5.05 (5%)
15.9 (15%)
2.8 (3%)
9.85 (10%)
3.95 (4%)
100.4
2 0.01 32.8
(63%)
0.02 (0.04%)
4.6 (9%)
7.5 (15%)
5.9 (11%)
- 1
(2%)
- - 51.8
3 217.0
(56%)
44.9 (12%)
58.2 (15%)
31.2 (8%)
10.6 (3%)
12.4 (3%)
2.0 (0.5%)
11.1 (3%)
- 1.55
(0.4%)
388.9
Total (kg)
217.0 (40%)
107.6 (20%)
58.2 (11%)
48.7 (9%)
41.1 (8%)
23.3 (4%)
17.9 (3%)
14.9 (3%)
9.9 (3%)
5.5 (1%)
544.1
Note: EPC = Ethylene/propylene copolymer and EVC = Ethylene/vinyl acetate copolymer
The majority of the plastic waste generated by building protection was PE (83%) whereas plastic typology from packaging was more varied (Figure 2). Construction components showed a very different plastics fingerprint with most derived from PVC or PC.
Figure 2. Percentage of polymer type (by mass) for plastic waste originating from Building Protection (BP), Product Packaging (P) and Construction Components (CC).
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The generation rate of product packaging plastics, based on project floor area can be compared with previous calculated values from research. In this study, this generation rate (averaged across all construction phases) was 0.0029 kg/m2 which lies between two previously reported values of 0.0019 kg/m2 by a study which suggested a likely undermeasurement4 and 0.53 kg/m2 by González Pericot et al25. For comparison with future audits, we have also calculated the plastic generation rate (averaged across all construction phases) for CC and BP as 0.075kg/m2 and 0.0075kg/m2 respectively.
4. Conclusions
The overall plastic waste production over a total build area of 4800m2 was 744kg. We estimate that there is a likely variance of +15 to 20%, which is due to plastics that were inadvertently disposed of to the wrong skip by site operators and sub-contractors. The main plastic source (by mass) was from CC (67.6%) (for example offcuts and surplus), followed by P (25.7%) and BP (6.5%). Packaging and plastics used for building protection were mainly comprised polyethylene whereas CC were mainly PVC or PC. The majority of the plastic mass was generated during the final building stage – interior fitout.
Diversion from landfill was not a key aim of the study, and the contractors were only able to recycle 21% by mass of all of the plastics generated (including all PVC pipework and polystyrene). This outcome is partly a reflection of the lack of staff training and site visits (due to COVID), the lack of recycling culture onsite and the complication of subcontractors disposing waste randomly. The lack of clear and appropriate signage on site (including images of waste types) has since been improved for future studies as well as the use of dedicated plastic bags rather than skips which encourage poor waste management practices. The authors predict that it should be feasible to recycle closer to 80% of the plastic waste from construction with better management systems, as well as finding new avenues of waste diversion which requires the collaboration between building, education, waste, retail and, governance sectors.
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6. Acknowledgments
The researchers would like to acknowledge the hard work and support from Julie Roberts (Mitre 10), James Griffin (Sustainable Business Network), Mark Roberts (Auckland Council), Clinton Jones (Green Gorillas), Simon Burden (Buildlink), Paul Charteris (Saveboard), Dane Faesen Kloet (Divert NZ) and Dwayne Carroll (Marley). We would like to thank BRANZ and acknowledge financial assistance from the Building Research Levy.