Trabajo fin de máster Edurne Suárez por la Technical University of Denmark en el departamento de Ingeniería Civil. Reciclaje de fibras provenientes de redes de pesca en desuso en cemento.

1. Recycling fishing nets into concrete
Master thesis - Edurne Suárez Lejardi
June 2018

2. Contents
1. Motivation
2. Introduction to the project
3. Part I – Microplastics in the Arctic
3.1. Analysis of impurities
3.2.Analysis of microplastics release
4. Part II – Recycled fibers as mortar
reinforcement
4.1.Casting and demoulding process
4.2.Mechanical properties
4.3.Free shrinkage characterization
5. Economic analysis and alternative solutions
6. Conclusions
7. Bibliography
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3. Causes ?
1. Motivation. Marine pollution.
12,700,000 tons of plastic waste
85% is plastic waste
30,000 nets are discarded
27% is fishing gear
Anually…
Consequences?
Recycling fishing nets into concrete – Master thesis – Edurne Suárez Lejardi – June 2018 3/26
Source: European Commission-Single-use plastics: New EU rules to reduce marine litter.
Circularocean.eu

4. 2. Introduction to the project. Project concept.
What are we doing ?
PE fibers as concrete
reinforcement
Which fibers are used?
Recycling fishing nets into concrete – Master thesis – Edurne Suárez Lejardi – June 2018 4/26
‘Yellow’ PE Fibers ‘Green’ PE Fibers

5. 2. Introduction to the project. Construction sector.
Fiber-reinforced concrete
• Widely used in the construction sector.
• Steel, glass, plastic and natural fibers.
• Improvement of mechanical properties.
• Tensile strength
• Chemical resistance
• Plastic and drying shrinkage
• Creep
Steel fibers PP fibers Glass fibers Natural fibers
Bending strength curve
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6. 2. Introduction to the project. Experimentation.
Part I – Microplastics in the Arctic
1. Analysis of impurities
2. Analysis of microplastics release
Part II – Recycled fibers as mortar reinforcement
3. Casting and demoulding process
4. Mechanical properties
5. Free shrinkage characterization
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7. Part I – Microplastics in the Arctic
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8. 3.1. Analysis of impurities
b) Methods
a) Objective
Quantify and characterize the impurities coming with the PE fibers:
1. Get an overview of the marine pollution in the Arctic.
2. Demostrate the need of a cleaning process .
6 x Sample 60 g Sieve 1 mm Sieve 250 µm
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9. 3.1. Analysis of impurities
Reference Sample
weight [g]
Impurities >1 mm
[g]
Impurities <1 mm
>250 µm [g]
Impurities <250 µm
[g]
Average [g] 0,60 0,14 0,20 0,26
Percentage [%] 100 24 32 44
c) Results
76 % impurities
(weight)
PE Fibers > 1 mm Impurities < 250 µmPE fibers + Impurities < 1 mm > 250 µm
 Sand, salt, clay, fibrillated microplastics and PE microplastics
 Necessity of a washing process
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10. 3.2. Analysis of microplastics release
Analyse the degradation and the release of microplastics from PE fishing nets in
the ocean during 2 months of experimentation.
Surface conditions
 Sea water
 UV light expousure
 Wave’s friction
 High oxygen levels
Under surface conditions
 Sea water
 Low oxygen levels
 UV light expousure
 Wave’s frictionPE Nets PE Fibers Set-up
b) Materials & Methods
a) Objective
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11. c) Results
3.2. Analysis of microplastics release
Test PE Fibers/Net Weight loss [g]
1 ‘green’ Net surface 0,03
2 ‘green’ Net under 0,01
3 ‘yellow’ Net surface 0,02
4 ‘yellow’ Net under 0,01
1
3
2
4
 Microplastics release:
 1- 2 months
 3- 1 month
 Loss of material: microplastics + impurities
‘yellow’ PE microplastic ‘green’ PE microplastic
3 1
 Mesh dimension and braided are
factors affecting the degradation.
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12. Part II – Recycled fibers as mortar reinforcement
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13. 4.1. Casting
b) Materials & Methods
a) Objective Cast 12 prism samples for each mix to test day 1,2,7 and 28 of curing.
Cast 6 bar samples for each mix for the microstrain analysis due to drying shrinkage.
Analysis:
A. Distribution of fibers
B. Specimens’ weights and dimensions
Reference Fiber type Fiber content [%] Number of samples
REF - - 0,0 12 + 6
REF PP PP 0,2 12 + 6
REF PE PE ‘yellow’ 2,0 12 + 6
REF PE2 PE ‘green’ 2,0 12 + 6
‘yellow’ PE fibersPP fibers ‘green’ PE fibers Prism sample Bar sample
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14. c) Results
A) Distribution of fibers in mixture B) Specimens’ weights and dimensions
• Homogeneusity
• No bunches
• Longitudinal fibers 78-92%
• Fibers protruding in the edges.
‘green’ PE fibers ‘yellow’ PE fibers
Difference between theoretical and experimental values
 Height and breadth:
• No significant
• Cause: molds made by hand
 Weight:
• Significant
• Cause: demolding process
Loss of material
4.1. Casting
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15. 4.2. Mechanical properties
Compare mechanical properties between waste PE and commercial PP FRM samples.
b) Methods
a) Objective
Bending strength
𝑹𝒇 =
𝟏. 𝟓 . 𝑭 𝒇. 𝒍
𝒃 𝟑
Toughness
𝑻 𝜹𝒄𝒓 =
𝟎
𝜹𝒄𝒓
𝑷𝜹𝒅𝜹
Compressive strength
𝑅𝑐 =
𝐹𝑐𝑚
𝑏.𝑏
Interface bonding
Analysis of the surfaces
• Debonding
• Porosity
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16. c) Results
Bending strength & Toughness
Ref -, Day 1
Ref PP, Day 1
Ref PE, Day 1
Ref PE2, Day 1
Ref -, Day 2
Ref PP, Day 2
Ref PE, Day 2
Ref PE2, Day 2
Ref -, Day 7
Ref PP, Day 7
Ref PE, Day 7
Ref PE2, Day 7
Ref -, Day 28
Ref PP, Day 28
Ref PE, Day 28
Ref PE2, Day 28
Increase in:
 Energy for the FRM samples
 Strength over time (post crack behavior)
 Strength over time (first crack)
0
2
4
6
8
10
Ref- Ref PP Ref PE Ref PE2
BendingStrength[MPa]
Day 1 Day 2 Day 7 Day 28
 Similar workability for both PE fibers
 Decrease in strength from day 7 to day 28
4.2. Mechanical properties
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17. c) Results
 Debonding more pronounced for PE
 Fibers were mainly pulled out of the matrix
 No degradation
 Low porosity
Compressive strength
0
10
20
30
40
50
60
70
Day 1 Day 2 Day 7 Day 28
CompressiveStrength[MPa]
Ref -
0
10
20
30
40
50
60
70
Day 1 Day 2 Day 7 Day 28
CompressiveStrength[MPa]
Ref PP
0
10
20
30
40
50
60
70
Day 1 Day 2 Day 7 Day 28CompressiveStrength[MPa]
Ref PE
0
10
20
30
40
50
60
70
Day 1 Day 2 Day 7 Day 28
CompressiveStrength[MPa]
Ref PE2
 Increase in strength over time
 Decrease in strength with fibers addition
Interface bonding- SEM Analysis
‘green’ PE fibers‘yellow’ PE fibers
PP fibers Mortar surface
4.2. Mechanical properties
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18. 4.3. Free shrinkage characterization
b)Methods
a)Objective
Analysis of the microstrain of bar mortar samples using two different methods:
• Linear Variable Displacement Transducer (LVDT) Test
• Digital Image Correlation (DIC) Method
𝜇𝜖 = 1000 𝑥
∆𝐿
𝐿0
LVDT DIC
Temperature 28-30 ºC
Relative humidity 25-30%
Period: 28 days
Environmental chamber
𝟏. 𝑷𝒂𝒊𝒏𝒕 𝟐. 𝑺𝒆𝒕 − 𝒖𝒑
𝟑. 𝑺𝒐𝒇𝒕𝒘𝒂𝒓𝒆
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19. c) Results
4.3. Free shrinkage characterization
0.0
0.4
0.8
1.2
1.6
2.0
0 5 10 15 20 25 30
Microstrainµe[µm/mm]
Time [days]
Ref - Ref PP Ref PE Ref PE2
LVDT test
 PP maximum microstrain 1,80 µm/mm
 Ref- maximum microstrain 1,32 µm/mm
 Similar workability PE FRM bars
 Variation
 Difference in bars’ microstrain from same mix
 Ref- highest maximum microstrain
 PP lowest maximum microstrain
 No similar workability PE FRM bars
DIC test
PE bars PE2 bars
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20. Parameter Average
Temperature (℃) 27,8
Dew Point (℃) 7,4
Humidity (% rh) 27,6
c) Results
4.3. Free shrinkage characterization
Sensitive changes caused by…
 Mix design
 Paint process
 GOM software
 Photos quality
 Cage set-up
 Camera fixation
 Environmental conditions
 Unsteady humidity  Microstrain variation
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21. d) Improvements
4.3. Free shrinkage characterization
Improve the environmental chamber characteristics to maintain
the temperature and humidity steady.
Same conditions:
• Temperature
• Humidity
• Separation among bars
• Light exposure
• Vibrations
• Wind
DIC
 Improve the painting process by finding a specific method
 Change the frequency of the photo shooting
 Better comprehension of the camera setups
 Improve camera fixation allowing the perpendicular movement
LVDT
 Three bars for measuring – Average
 More bar molds
For all the bar samples…
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22. 5. Economic analysis and alternative solutions
Company:
Cost: 30 DKK/kg
Commercial PP fibers
How to avoid or reduce fishing nets discarded into the ocean? How to boost the idea of the project commercially?
 Cheaper fishing nets reparation
 System of incentives for returning the fishing nets ashore
 Harder legislation for marine pollution.
 System of incentives for construction companies
 System of incentives for fishing nets’ collecting
companies.
Waste PE fibers
Company:
Cost: 3 DKK/kg
Economic benefit
Environmental benefit
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23. • Quick microplastics release.
• Nets floating in the surface degrade more because of wave friction, oxygen and UV
light.
• The mesh dimension and braided of the nets are factors affecting the degradation.
PART I
PART II- Methods I
• Homogenous distribution of waste PE fibers and high percentage of longitudinal fiber
(>70%).
• Difference in weight mainly caused by the demolding process, which causes material
lost.
6. Conclusions
Casting
Microplastics
Impurities
• High quantity of impurities (76%): sand, salt, clay, PE microplastics and other
microplastics that proved the necessity of a washing process.
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24. • Waste PE FRM results similar to commercial PP FRM values.
• Temperature and humidity affected the mechanical properties.
• Compressive strength increased over curing time and was higher for reference
samples.
• Poor fiber-to-matrix mechanical and chemical bonding.
• ‘yellow’ and ‘green’ PE fibers showed similar workability.
PART II- Methods I
PART II- Methods II
• LVDT and DIC results were totally the contrary.
• Variation on humidity caused microstrain variation, making impossible to
contrast results.
• The same environment conditions should be maintained.
6. Conclusions
Mechanical properties
Dry shrinkage
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25. 6. Future studies and improvements
• Deep characterization of the microplastics found in the impurities.
• Microplastics release experiment repetition in bigger scale and longer period
• Test and analyse the affectation of the curing temperature and humidity variation
• Analyse the water evaporation
• Design a new environmental chamber to maintain the conditions steady .
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26. 7. Bibliography
1. A. K. Jassim. Recycling of Polyethylene Waste to Produce Plastic Cement. University of Basrah,
College of Engineering, Materials Engineering Department, Basrah, Iraq. Procedia Manufacturing Vol.
8, 2017, pages 635 – 642.
2. Dr. P. J. Kershaw. Marine plastic debris and microplastics. Global lessons and research to
inspire action and guide policy change. UNEP, 2016.
3. DS/EN-196-1. Methods of testing cement – part 1: Determination of strength. Dansk Standard.
2005.
4. P. Kumar Mehta. Concrete: microstructure, properties and materials. Mc Graw Hill Education,
fourth edition, 2014.
5. U. Oxvig and U.J. Hansen. Fishing gears. Fisheries circle. 2nd edition, 2007, Pages 11-22.
6. Circular Ocean Interreg Project (2015). Circular Ocean: Challenges. Recovered from
http://www.circularocean.eu/challenges/
7. European Commission (28 May 2018). Single-use plastics: New EU rules to reduce marine litter.
(Press release). Recovered from http://europa.eu/rapid/press-release_IP-18-3927_en.htm
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27. Recycling fishing nets into concrete
Master thesis - Edurne Suárez Lejardi
June 2018