The document discusses the design and production of the world's first movable bicycle bridge made entirely from natural fibers and a bio-based resin. Key points include: - The bridge in Ritsumasyl, Netherlands uses flax fibers and a 33% bio-based epoxy resin for the deck material. - An extensive research program tested the material properties of the bio-composite, including tension, compression, creep, and fatigue resistance. The results showed lower strength but also benefits like reduced moisture absorption with coatings. - Lessons learned include the sensitivity of the material to moisture, the non-linear stress-strain behavior, and ensuring proper resin wetting of the natural fibers during production.

1. Making Advanced Materials More SustainableMaking Advanced Materials More SustainableMaking Advanced Materials More SustainableMaking Advanced Materials More Sustainable
The Advent of Bio Composite BridgesThe Advent of Bio Composite BridgesThe Advent of Bio Composite BridgesThe Advent of Bio Composite Bridges
ir. Wouter Claassen, April 2019
https://www.drive.frl/nl

2. Content
2
• Short introduction Witteveen+Bos
• Short introduction into bio-composites
• The design process of the bridge
• The research program
• The production
• Lessons learned
• Monitoring program

3. Content
3
• Short introduction Witteveen+Bos
• Short introduction into bio-composites
• The design process of the bridge
• The research program
• The production
• Lessons learned
• Monitoring program

4. ˗ Bos (37): Civil engineer (Enschede)
˗ Witteveen (54): Director Public Works (Rotterdam)
˗ Urban Development Consultancy and Engineering Office, called: Witteveen+Bos
˗ First project: lock Prince Bernhard Deventer
˗ Milestones:
· 1994: 500 employees
· 2019: > 1100 employees
˗ Board of directors (2 members)
Witteveen+Bos is established in 1946
4

5. ˗ Product-market combinations (PMCs) / Business units
· Dedicated to own products
· Specific market segment
˗ Built Environment
˗ Deltas, Coasts and Rivers
˗ Energy, Water and Environment
˗ Infrastructure and Mobility
Areas of expertise
5

6. 6

7. Mile stone 2010: First movable 60 ton bridge in the world
7
- Hoofdbrug Oosterwolde
- Design Witteveen+Bos

8. Mile stone 2019: FRP Slides Enclosure Dam
8

9. Goal 2019: First movable bio-based bicycle
bridge in the world, Ritsumasyl
Span: 22m!
100% natural fibres, bio-based resin
Year of construction: 2018-2019
9

10. Our GOAL for the future
10
Not only use bio-based composites,
but use 100% green composites
(100% natural fibres + 100% bio resin)
Bio-based and circular economy
Construction
Compost

11. Content
11
• Short introduction into bio-composites
• The design process of the bridge
• The research program
• The production
• Lessons learned
• Monitoring program

12. Definition bio-based composite bridge
12
A bio-based composite bridge consist in whole or in
significant part, of natural products
or renewable domestic agricultural materials (including
plant, animal, and marine materials) or forestry materials.

13. Advantages and disadvantages of bio-based composites
13
- Acceptable specific strength properties
- Renewable resource
- low density
- Well isolation for sound, temperature and vibratory
- Well chemical resistance
- Non-abrasive
- Aesthetic
- Biodegradable if resin is 100% biosourced
- Sustainability
- Low CO2 impact
- Creep behavior
- Moisture sensitive
- The natural variability of fibre
- Durability
- Fatigue behavior understudied
- Fire resistance
- Fibre matrix adhesion
- Limited maximum processing
temperatures
- Impact resistance

14. Degradation mechanisms
14
• UV resistance
• Water resistance (Osmosis, Hydrolysis)
• Chemically inert
• Frost resistance
• Salt resistance
• Snow resistance
• Temperature resistance
• Lightning resistance
• Biodegradation resistance

15. Cellulose
15Source: www.bio.miami.edu/dana/226/226F09_2.html
Celluslose chain
High mechanical strength
Held by Hydrogen bonds
Glycosidic bond
(Macro)Hydroxile group
Monomer
β-D-glucopyranose units
Chemical properties,
Oxidized, esterified of
converted into esthers

16. Water
16
• The major challenge is the hydrophilic nature of natural fibres, which make
them prone to water absorption and, as a consequence, lead to poor
adhesion to hydrophobic polymer matrices.
Synthetic fibre / Matrix Natural fibre
Hydrophobic Hydrophilic
Degrade (an) aerobically

17. Mechanical properties of Flax compared to E-Glass
17
Properties
Flax
(Less than 100% Cellulose) E-Glass
Modulus of elasticity 55.000 - 75.000 72.000 - 80.000 MPa
Shear Modulus 1.600 30.000 MPa
Tensile strength 800 - 1.500 2.800 MPa
Compression strength -830 to -1.570 -2.800 MPa
Tensile fracture strain 1,5 - 2,0 3,9 %
Poisson ratio 0,25 0,20 -
Density 1,4 - 1,5 2,4 – 2,6 kg/dm3
Thermal expansion coefficient 5,0 2,8 – 5,0 *10-6/°C
Heat conduction coefficient 0,06 1,05 W/mK

18. Natural fibers versus Glass fibers
18
• Low specific weight
• Renewable resource
• Low carbon footprint
• Less wear tools
• Good thermal and acoustic
insulation
• Different tools needed
• Lower impact strength
• Variable quality and price
• Impact moisture
• Limited processing temperature

19. Content
19
• The design process of the bridge
• The research program
• The production
• Lessons learned
• Monitoring program

20. It all started with … Timeline
20
• A dream and a wish: Sieds Hoitinga the Program manager at Provincie Fryslân wanted a bio-based bridge
• Begin 2016: Literature study Witteveen+Bos
• Mid 2016: Pre-selection contractor
• Mid 2016: Preparation tender documents bio-based deck
• End 2016: Tender on the market
• Begin 2017: Final contract signed with producer and contractor
• End 2017: Literature study producer bio-based deck
• Begin 2018: Start testing program producer
• April 2018: First reports of the final design phase have been submitted
• April 2018: Agree on the feasibility of the design
• End 2018: Finishing the final design
• 2019: Detailed design phase
• Begin 2019: Start building the bridge

21. Reuse of the old bridge
21

22. Boundary conditions:
22
• Design life: 100 years
• 100% natural fibres
• Bio-based resin
• 100% natural core
• Max height deck 1200 mm
• Total width deck: 3,65 m

23. 23

24. 24

25. 25

26. 26

27. 27

28. Chosen materials used for the bridge (1/3)
28
Epoxy resin:
Resoltech 1800 ECO + 1804 ECO (100:24), 33% biobased on the mix
• Very low temperature at exothermic peak
• Long potlife
• Constant low viscosity
Balsa Core:
BALTEK® SB 150

29. Chosen materials used for the bridge (2/3)
29
Fibers:
BComp 5025 Amplitex UD300: UD 278 gr/m2
= Flax Unidirection 278 gr/m2
UD: 0,43 mm thick
BComp 5008 Amplitex Biax 350: +/-45 graden 354 gr/m2 =
Flax Bi-axial +45 graden 77 gr/m2 + -45 graden 77 gr/m2
Coatings:
First layer variopox epoxy resin coating
2 toplayers maxguard gelcoating

30. Chosen materials used for the bridge (3/3)
30
Anti vandal coating:
PSS-20 clear bio-based:
Natural polysaccharides (starch) and water
Bonding paste
Vinylester Oldopal 740 0110

31. FEM model
31

32. 32

33. Content
33
• The research program
• The production
• Lessons learned
• Monitoring program

34. Research Programme bio-based movable bridge Ritsumasyl
34

35. 35

36. Research and testing program
36
• ILSS (used to determine best fiber resin combinations)
• Tension
• Compression
• Shear
• Hot/wet behaviour
• Creep (very important!)
• UV (still ongoing)
• Fatigue
• Connections

37. 37

38. Laminated properties
38
Measured Design value
• ILLS: 33,3 / 22,1 /
• Tension: 363 / (3x lower than glass) 166 /
• Compression: 117 / 79,6 /
• Modulus of elasticity : 24,6 GPa (50% lower than glass) 24 GPa
• Modulus of elasticity : - 5 GPa
• G-modulus - 1,4 GPa
Tension strength is higher than the compression strength

39. Hot-wet testing
39
30 45 60
75

40. Results hot-wet testing
40
• The decrease of modulus of elasticity under wet circumstances is a factor 4 greater
than that of a glass fibre polyester;
• Not every coating prevents the fibres 100% from absorbing moisture;
• After 1 day the moisture absorption is 10-20 times higher than with Glass fibers
• Uncoated hot-wet factor: γhot-wet;100 years = 1,637
• Coated hot-wet factor, multiple layers: γhot-wet;100 years = 1,016

41. Creep
41
• Creep is one of the most important parameters to
take into account
• High stresses lead to rapidly increasing creep
• Boundary conditions Ritsumasyl:
• 10,000 openings per year,
• 1 minute open +
long openings during maintenance and failure
1
1,5
2
2,5
3
3,5
-10000 0 10000 20000 30000 40000
Creepfactor
Days
Creep factor UD (15 MPa)

42. Cyclic creep
42
• 2 samples tested by Stenden
• 155 days pre-creep
• KEB1 with 13,2 MPa and KEB2 with 8,9 Mpa
• cyclical variation between 16.1 MPa for 5 minutes (open bridge) till 9.9 MPa for 10
minutes (closed bridge).
• 10% of the time the bridge is open

43. 43
KEB2 = 1,33
KEB1 = 1,19
Cyclic creep is higher when the pre creep is lower!

44. Building the full scale model (13 meters)
44

45. Post curing
45

46. Creep testing
46

47. 47
Fatigue

48. Fatigue test
48
• 50 year, 10.000 cycles a year + 50 years including extreme temperature influence
• Total > 1.000.000 cycles = NO DAMAGE

49. 49

50. 50
Laminate thickness: 20 mm
Bolt: M30
EngelsEngels

51. 51

52. Content
52
• The production
• Lessons learned
• Monitoring program

53. 53Building the fixed bridge

54. 54

55. 55

56. 56

57. 57

58. 58

59. 59

60. Content
60
• Lessons learned
• Monitoring program

61. 61
UD-ply
Flax-Epoxy Glass-polyester
[MPa] [MPa] Factor
σt1
166 840 5,1
σ2t
22 45 2,0
σ1c
-80 -630 7,9
σ2c
-22 -160 7,3
τ12
22 45 2,0

62. Moisture uptake
62
• From their natural origin there is still moisture in the material, This
in no problem but you should be aware of it during production;
• Be aware that the amount of moisture in the fibres is more than on
the product data sheets.

63. Stress-Strain curve for bio-composites
63
• Due to non-linear behaviour
change of modulus of
elasticity
• With imposed force the
microfibrils arrange to a
higher degree of crystallinity
which leads to better
mechanical properties

64. Resin
64
• For the epoxy the peak exotherm is very important to prevent degradation of the
fibres, max. around 100 degrees;
• The viscosity should be low enough;
• Bonding: not every resin is suitable for natural fibres

65. Traditional Failure modes Bio-based Failure modes
Water
Fibres
65
• Creep and water are the main degradation mechanisms

66. Rule of mixture
66
• The rule of mixture to determine the stiffness with a micro-mechanic approach
doesn’t completely comply for Bio-based composites
• The stiffness will be lower than according to the rule of mixture, due to?
• Not sufficient wetting of the fibres?
• On a microscale the stiffness of the fibre differs per section, witch contributes to a
lower overall stiffness?
• The shear connection between the short, non-homogenous fibres is below 100%?
• Stiffness, strength and elongation should be based on test results

67. Processing the material
67
• Problems with normal FRP equipment;
• Material is very viscous;
• Diamond sawing and drilling equipment doesn’t work well;
• Best to use equipment for wood processing.

68. Indication displacements
68

69. 69
Frozen
moisture
in the
fibers
moisture
releasing
– extra
expansion
moisture
evaporates
– lower
expansion
Creep effect
greater them
the thermal
expansion

70. 70
-10
0
10
20
30
40
50
60
70
80
90
-40 -30 -20 -10 0 10 20 30 40 50 60 70
Expansioncoefficient(10-6K-1)
Tempratur (C)
Expansion coefficients UD-ply
α1 TU-Delft α2 TU-Delft α1 KU-Leuven
α2 KU-Leuven α1 Glass-epoxy α2 Glass-epoxy

71. 71
1
1,67
1,92
2,9
3,29
1
1,67
1,92
2,41
2,61
1
1,5
2
2,5
3
3,5
0 5000 10000 15000 20000 25000 30000 35000 40000
Creepfactor
Days
Creep factor
Pre creep
Total creep factor
Creep factor, cyclic creep
Creep factor Glass epoxy, windturbine blades
Design curve

72. Warping of the Formwork
72

73. Creep-Fatigue
73

74. Cyclic fatigue
74
The Modulus of elasticity of a composite laminate tends to reduce under the effect of
cyclic fatigue. The main reason for the modulus change is the formation of
accumulation of matrix cracks during tensile fatigue loads. The matrix cracks reduce the
matrix dominated axial stiffness values.

75. Mistake CUR 96
75
Wrong Correct
Formulas based on the goodman
diagram

76. Bio-based percentage
76
Bio percentage
Balsa 100% 247kg/m³
Flax 100% 1350kg/m³
Bonding paste 0% 1200kg/m³
Resin / harder injection 34% 1190kg/m³
Resin / harder hand laminate 31% 1120kg/m³
Laminate weight (injection) 69% 1270kg/m³
Laminate volume (injection) 69%
Laminate weight (hand laminate) 65% 1224kg/m³
Laminate volume (hand laminate) 69%
Total: 83% /m³

77. CO2 footprint
77
Fibre ton CO2 / ton fibres
Primary energy use
GJ/ ton
Carbon 1,7 180-290
Glass 2,2 15-35
Flax 0,7 7
Source: Green Pac / - JNC15

78. LCA (draft version)
78
• The LCA inquiry is preformed according the ILCD manual for LCA (2010) (which are
based and compliant ISO 14040 and 14044)
• Comparison Flax-bio-epoxy bridge with a glass-vinyl ester bridge
• Quaternary recycling: burning for energy generation
Construction
Energy

79. 79
• Design conclusions: equal dimensions and equal total weight (matrix + fibers)
• Equal environmental impact bio-resin and chemical resin, due to the extra amount of
bio resin
• Glass fibers have the greatest impact on the environment (2,5-3 times)
• Raw material scarcity of glass fibers compared to the renewable flax fibers
• Flax fibers greater impact on land use
LCA (draft version)

80. 80
Source: Composites UK Ltd
Primary energy use

81. Biosolvolyse
81Source: Biosolvolyse by Avans

82. Content
82
• Monitoring program

83. Main Goal
83
• The main goal of the monitoring plan is to obtain more data-driven insights and
knowledge about the bio-based composite deck of the bridge. This concerns the
condition, properties, behavior and lifetime of the composite deck.
Engineering
monitoring plan
Data
management
Acces of the
information
management
and
maintenance

84. Deck (movable)
Equipped with optical sensors
Weather station:
• Relative humidity
• Precipitation
• Wind + direction
• Temperature + direction
Data acquisitie unit
Transport data –
fiber optical
cable
Disclosure of
information
Deck (Fixed)
Equipped with optical sensors

85. Possible Non-destructive Testing (NDT) methods
85
• Visual inspection
• Infrared Camera and Heating System
• Identifying debonded areas which correspond to the “hot spots” or brighter
areas in the image.
• Digital Tap Hammer
• Detecting delaminations in thin composites and for detecting debonds between
FRP composite wraps and underlying concrete member
• Fibre optic sensors
• Intended to measure the deformation and the stresses in the construction and
to compare them with the reference value

86. Proposed NDT Methods
86
• Visual inspection
• Fibre optic sensors
• Strain of the bridge unloaded
• Expansion
• Strain of the bridge under normal loading conditions
• Stresses
• Deformation
• Strain and of the bridge during swing action
• Stresses
• Fatigue
• Moisture uptake

87. Visual inspection
87
• Uneven colour
• Crazing (micro-cracking)
• Some corners devoid of gelcoat
• Leakage between joints
• Loss of sealant
• Dirt
• Organic growth
• Other evidence of water
• Cracking and debonding of surface
• Cracking at construction joints with
other components
• FRP delamination from corroded bracket
• Surface chalking, secondary cracks
• Cracking at angles owing to thermal
stresses

88. Fibre optic sensor
88
• Brillioun sensors for the distribution measurements
• Relative cheap sensors but an expensive interigator
• Bragg Grating glass fiber sensors for dynamic measurements
• An absolute sensor technology that allows coupling and decoupling of the
sensors with the data acquisition unit without recalibration

89. 89
Strain
Strain Strain
Brillouin sensor interigation

90. 90
Bragg Grating Fibre optic sensors

91. 91

92. 92

93. Temprature sensor
93
• Resolution: 0,3°C
• Measuring range: -20°C - 150°C
• Diameter: 1 mm
• Sensor length: 8 mm

94. Sensoring
94
• Output = ASCII-format;
• Every 10 minutes 1 file with data;
• 8 channel interigator that controls 204 sensors (24 temp – 180 normal FBG);
• Postcurring no problem, Rooving from Glass, Temperature till max. 200 degree are
acceptable;
• Maximum measuring frequency: 2 KHz;
• High frequency used for determining natural frequency;
• 100 Hz used as standard value to measure al the unintended vehicles;

95. 95

96. 96
0 5 10 15 20 25 30 35
Position [m]
Fixed bridge sensors
Start Support 3 Support 4 Mid span Support 5 Mid span End FBG sensoren Temp Sensoren

97. 97
0 5 10 15 20 25 30 35
Position [m]
Movable bridge sensors
Start Support 1 Support 2 Mid span Support 3 Mid span End FBG sensoren Temp Sensoren

98. 98
Circular Award 2019
Puclic award
Nominatie De Nederlandse
Bouwprijs 2019
Top 3 InfraTech Innovatieprijs
Nominatie
Lighthouse
club
Award 2019

99. www.witteveenbos.com
Questions, contact:
ir. W. Claassen
Mail: wouter.claassen@witteveenbos.com
Tel: +31 (0)6 27 16 98 56
https://nl.linkedin.com/in/wouterclaassen