1. Good Morning
I’m Andrea Baliello and I’m a civil engineer.
I’m attending a PhD course at the Department of Civil-Environmental Engineer and Architecture at the University of Udine and
today I will show you a presentation titled «Aesthetic Transparent Road Pavements for Urban Heat Islands Mitigation and Landscape Preservation».

2. Urban Heat Island Urban Heat Island – UHI 1
Negative impacts related to urbanization is an increasing concern capturing the attention of people worldwide
Urban Heat Island – UHI
Temperature distribution
33°C
Rise in temperature related to anthropized activities, manifested in any urban area where surfaces are prone to release large quantities of heat.
32°C
31°C
30°C
UHI negatively impacts humans and associated ecosystems located far away from cities.
29°C
Urban heat island generally identify all phenomena related to temperature rising manifested within urban areas, where surfaces are prone to release large of quantities of heat, which can negatively affect humans health.
On the left side, you can see an example of a typical temperature distribution across city, suburban and rural areas, with significant difference on heat distribution (difference in mean temperatures up to 3 – 4 degrees).
UHIs are indirectly related to climate changes
(contributing to greenhouse effect and global warming). 
Rural
Suburban
Commercial
City
Residential
Park
Suburban
Farmland

3. 2
Urban Heat Island
Negative impacts related to urbanization is an increasing concern capturing the attention of people worldwide
Urbanization
Road Pavements
Around half of the world human population lives in urban areas.
Dark asphalt pavements cover a high percentage of the urban area, largely affecting the development of the UHI phenomenon. A C
Nowadays, population migration from rural to urban/suburban areas is still continuing.
Generally, they are realized with high-emissivity materials responsible of heat concentration enhancing.
In 2030, it is expected that global urbanization rate will increase by 70%.
As example, conventional asphalt pavement could reach over 60 °C with hot summer climate.
UHI Main Causes
Mitigation Strategies
Lack of vegetation inhibiting radiation interception and shade production.
Urban Heat Island is generally connected to urbanization phenomenon.
This is an increasing concern capturing the attention of people worldwide, since it is still continuing. In two thousand thirty, it is expected that global urbanization rate will increase by 70%.
Principally, UHI main causes concern all anthropized activities, but, in general, they are related to the lack of vegetation and the large amount of buildings with non-reflective surfaces, but also to the presence of the dark surfaces of roads.
In fact, road pavements cover a high percentage of the urban area and are realized with high-emissivity materials.
As example, during summer, a conventional asphalt pavement could reach temperature of sixty degree.
Thus, a successful mitigation strategy can be addressed also at developing new clear or colored road pavements designed with innovative methods and materials.
Vegetation preservation/requalification with natural area in the proximity of urban center.
Buildings presence, with high-percentage of non-reflective and water-resistant surfaces tending to absorb radiations.
Cooling building roofs and surfaces with new designs and materials.
Narrow buildings arrangement, causing the radiation entrapment and obstructing the air flow. B D
Realization of Innovative Road Pavements (e.g. Colored/Transparent) able to lower the heat concentration and diffusion.
 NEW PAVEMENT MATERIAL AND DESIGNING METHODS
Dark surfaces of road infrastructures.
Urbanized area pollution related to waste production, conditioning/refrigeration systems and industrial processes.

4. Landscape Preservation3
Landscape Preservation
Colored Pavements
Landscape preservation: example of red asphalt mixture.
Paving operations in a mountain Italian road
Infrastructure Insertion
Despite of its social connotation, each road infrastructure produces relevant impacts on the landscape.
Actual consciousness addressed to landscape preservation leads to consider this kind of impacts as one of the most relevant parameter, even determining the global performance of road infrastructure.
Sustainable solutions could be achieved utilizing both specific design guidelines and adequate materials.
Colored Pavements
Colored pavements represent a promising way to promote this preservation, guarantying a sustainable insertion of the road in the landscape.
Moreover, a colored pavement could represent a promising way to promote landscape preservation, contributing to guarantee a sustainable insertion of road infrastructure in the landscape.
On the left side, for example, you can see some paving operations with red asphalt. In particular, this work was realized in an Italian mountain village, so an area with high landscape value.
Actually, they are slightly diffused (the majority are used in areas with landscape value, as example mountain villages).
Improving the visibility in several light conditions, colored pavements are useful also to improve road safety.
They could be realized with several techniques, that determine the final chromatic performance (as examples: modified asphalt mixture with oxides or with innovative binders and aggregate, painting, etc…).

5. 4
Experimental Plan
Rheological Assessment
STUDY OBJECTIVE
Preliminary Phase: Characterization of resin mastics useful to produce transparent road pavements
Dynamic tests comparing the rheological characteristics of synthetic transparent resin with those of organic bitumen.
Chromatic Assessment
Visco-elasticity evaluation: DSR amplitude sweep – Oscillatory test; Fr.: 1.59 Hz; Def: 0.01 to 100%; T.: 34°C.
Mid-service temperature properties: DSR freq. sweep – Oscillatory test; Fr.: 0.1 to 100 rad/s; Def: 0.05%; Temp: 16 to 48°C.
Rutting analysis: DSR multiple sweep creep recovery – Rotational test; τ: kPa; 10 cycles (1s creep, 9s recovery); T.: 58 °C.
Dynamic Shear Rheometer
So, given this introduction, today I will present you an experimental characterization of an innovative transparent road.
In particular, I’ll show a preliminary study that characterize synthetic transparent resin and mastics useful to produce this kind of pavement.
This experimental plan was split in two parts. The first one, concerning a rheological assessment of medium and high service temperature properties of materials.
The second one, about a chromatic analysis of this resin, with the evaluation of tone/shade/ lightness and dominant color through a Digital Image Analysis .
Chromatic test comparing the characteristics of synthetic resin with those of organic bitumen.
Resin color evaluation: Digital image analysis, Tone/Shade/Lighting and Dominant color – Un-aged, RTFO-aged, PAV-aged.
Mastic color evaluation: Digital image analysis, Tone/Shade/Lighting and Dominant color – Un-aged, PAV-aged.
Digital Image Elaboration

6. Materials - Sample Preparation5
Materials - Sample Preparation
Maintaining constant binder-filler volumetric proportions to ensure analogue coating mechanisms
Binder
volumetric
dosage
73 % *
Fillers
27 %
FILLERS
BINDERS
Limestone
Specific Weight: 2.74 Mg/m3 – Natural rock L
Bitumen
Specific Weight: 1.01 Mg/m3 P
Steel Slag
Specific Weight: 3.86 Mg/m3 – Recycled S
Resin
Specific Weight: 0.72 Mg/m3 R
Cement
Specific Weight: 3.15 Mg/m3 – Natural rock C
* According with Superpave specifications
Binder and fillers heated at 150 °C for 2 hours.
Mechanical blending of binder and filler at 150°C
to obtain homogeneous mastics.
Basalt
Specific Weight: 2.77 Mg/m3 – Natural rock B
Materials are here indicated.
We studied synthetic resin in comparison with traditional bitumen and different kind of fillers, in order to prepare
different mastics. In particular, natural limestone and basalt, cement and recycled steel slag.
As you can see, volumetric proportion was dosed at 73 % of binders and 27 % of filler aggregates, according with Superpave specifications.
MASTICS RL
Resin-Limestone Mastic RS
Resin-Steel Slag Mastic RC
Resin-Cement Mastic RB
Resin-Basalt Mastic

7. Rheological Results: Medium-Temperature Service6
Rheological Results: Medium-Temperature Service
Evaluation of binder responses: from 16 to 48 °C.
Analysis of Linear Visco-Elastic (L.V.E.) Domain – Amplitude sweep tests (strain varying from 0.01 to 100%) at 1.59 Hz of freq.
Rheological Responses – Frequency sweep tests (frequency varying form 0.1 to 100 rad/s) at 0.05% of def.
Bitumen
Synthetic Resin
Linear Visco-Elastic Domain (L.V.E.)
Black Diagram
10 0
10 3
10 5
10 7
10 9
90°
70°
50°
30°
10°
Phase Angle
Complex Modulus
0.01 1
0.1 10
100
101
103
106
104
105
102
Strain
Shear Stress
L.V.E.
Identified with 95% G* decrease:
- Bitumen: 8.00 %
- Resin: 50.1 %
L.V.E.
L.V.E.
Rheological Response
Time-temperature superposition elaboration:
- Bitumen: Viscous properties
- Resin: Simple thermo-rheological behavior
NOT RECOGNIZED
Rheological results at medium temperature are expressed in graphs.
On the left, is represented the linear visco-elastic domain of resin and bitumen.
Bitumen gave a linear visco-elastic limit of about 8.00 %, whereas resin of about 50%, thus it could be supposed that resin had a high elasticity.
On the right graphs, are reported the Black Diagram of bitumen and resin.
As expected, bitumen showed a simple thermo-rheological behavior (so the aligned grey line).
Instead, resin (the orange curves) seemed to did not follow this scheme. Thus, although we demonstrated
different rheological behaviors of these two material, resin had comparable stiffness values with those of bitumen.

8. Rheological Results: High-Temperature Service7
Rheological Results: High-Temperature Service
Evaluation of high temperature behavior in terms of rutting potential (permanent deformation resistance)
Jr : Recovery Creep Compliance at 58 °C
Bitumen
Strain
Bitumen
Resin
Creep Test: cycle example (τ:3.2kPa, T: 58°C)
εmax
Resin
70%
Jr: Recovery Compliance.
Normalized elastic recovery:
 HIGH-ELASTIC RESIN
34.1
23.5
εstart
εend
60%
εmax
1.73
5.43
τ: 3.2 kPa
εstart
εend
Rutting Response
Traditional G*/sen δ evaluation:
 SIMILAR MATERIAL TRENDS
50%
τ: 0.1 kPa
1 sec
10 sec
Then, some resin’s benefits related to high temperature service could be evinced with creep recovery tests, so analyzing the permanent deformations.
On the right, you can see, in orange, the higher attitude of resin to deformations recovery, that can be probably due to the higher elasticity of the material.
Also accounting the recovery creep compliance and the rutting resistance indexes, the orange bars on the left, you can see the ability of the resin to prevent the rutting potential typical of the higher temperatures.
Bitumen
G* / sen δ: Rutting Resistance Index at 58 °C
Resin
34.9 kPa
31.5 kPa
High elasticity of resin able to mitigate permanent deformation (rutting) potential
9.13 kPa
5.96 kPa
ω: 100 rad/s
ω: 10 rad/s

9. Chromatic Assessment Results8
Chromatic Assessment Results
Evaluation of tone/shade/lightness and determination of dominant RGB color
Original Materials
Bitumen
Resin
Resin RTFO
Un-aged Resin
RTFO Resin
PAV Resin
L: 141
Med: 141
Std: 63.6
R: 201
G: 131
B: 37
L: 126
Med: 126
Std: 91.2
R: 193
G: 113
B: 1
Bitumen
Resin PAV R R
L: 5
Med: 5
Std: 12.6
R: 9
G: 6
B: 2
L: 110
Med: 110
Std: 68.8
R: 178
G: 97
B: 1 P R
Binders
Chromatic results are reported in this slide.
First line indicates all tested binders, whereas second one the utilized fillers.
Tone/shade/lightness and dominant color of materials are given in the circular graph.
Fillers
Limestone L B
Basalt
L: 189
Med: 189
Std: 10.8
R: 195
G: 189
B: 175
L: 65
Med: 65
Std: 11.8
R: 71
G: 64
B: 56
Steel Slag
Cement
Basalt
Limestone S C
Steel Slag
Cement
L: 60
Med: 60
Std: 11.4
R: 60
G: 61
B: 58
L: 122
Med: 122
Std: 21.5
R: 133
G: 120
B: 106

10. Chromatic Assessment Results9
Chromatic Assessment Results
Evaluation of tone/shade/lightness and determination of dominant RGB color
Mastics
Un-aged RL
Resin-Steel Slag
Resin-Cement
Un-aged RS
Un-aged RC
Un-aged RB
L: 15
Med: 15
Std: 2.4
R: 16
G: 15
B: 20
L: 37
Med: 37
Std: 3.1
R: 52
G: 34
B: 9
Resin-Limestone RS
Resin-Basalt R RC R
L: 81
Med: 81
Std: 2.3
R: 102
G: 79
B: 38
L: 24
Med: 24
Std: 6.4
R: 25
G: 23
B: 26 RL RB R
Un-aged
PAV RL
PAV RS
PAV RC
PAV RB
In analogy, same data are plotted for mastics, prepared with limestone, steel slag, basalt and cement fillers.
As you can see, the first line shows un-aged mastic, and second one aged mastics (where the resin was previously subjected to a PAV aging method, a laboratory procedure to simulate a long term aging typical of 5-6 years of service life).
Then, singularly comparing chromatic results we were able to indicate some interesting findings.
PAV – Aged RL RB
Resin-Limestone
Resin-Basalt
L: 68
Med: 68
Std: 5.3
R: 94
G: 65
B: 18
L: 19
Med: 19
Std: 5.7
R: 20
G: 19
B: 10 RS RC
Resin-Steel Slag
Resin-Cement
L: 14
Med: 14
Std: 1.2
R: 15
G: 14
B: 13
L: 31
Med: 31
Std: 4.5
R: 48
G: 33
B: 2

11. Un-aged Resin PAV-aged Resin10
Results: Chromatic Assessment
Aging effect on Resin color and Lightness – Simulation with PAV procedure
Un-aged Resin
PAV-aged Resin R R
RGB dominant tone – Lightness Value
RGB dominant tone – Lightness Value
R:201 - G:131 - B:17
R:178 - G:97 - B:1
Lightness
Lightness value: 141
Lightness value: 126
126
Lightness
Original Sample
141
Original Sample R
pixel
pixel B G G B R
First of all, un-aged resin versus PAV-aged resin.
As you can see, there was a negligible color variation for the resin subjected to long-term aging procedure, with not significant color differences and darkening effects (so similar lightness values). 17
178
131 97
201 1
NEGLIGIBLE color variation for Resin subjected to long-term aging (normalized Pressure Aging Vessel procedure)
NOT SIGNIFICANT darkening effect, with similar lightness value after long-term aging.

12. Results: Chromatic Assessment11
Results: Chromatic Assessment
Aging effect on Limestone Mastic color and Lightness – Simulation with PAV procedure
Un-aged R-Limestone Mastic RL
PAV-aged R-Limestone Mastic RL
RGB dominant tone – Lightness Value
RGB dominant tone – Lightness Value
R:102 - G:79 - B:38
R:94 - G:65 - B:18
Lightness value: 81
Lightness value: 68
Lightness
Original Sample 68
Original Sample
pixel
Lightness 81
pixel B G R R G B 94
Moreover, analog considerations can be made for mastics, as examples, resin-limestone one.
Thus a slight darkening effect and a not significant aging effect. 65 18 38
102 79
NEGLIGIBLE color variation due to PAV aging also in the case of mastic (e.g. Resin-Limestone)
SLIGHT darkening effect, with similar lightness value after long-term aging.

13. Results: Chromatic Assessment12
Results: Chromatic Assessment
Filler typology effect on mastic color and lightness
Resin-Limestone Mastic
Resin-Steel Slag Mastic
Resin-Cement Mastic
Resin-Basalt Mastic
Resin
Limestone
Resin
Steel Slag
Resin R
Cement C
Resin
Basalt R L R S R B
L: 126
Med: 126
Std: 91.2
R: 193
G: 113
B: 1
L: 189
Med: 189
Std: 10.8
R: 195
G: 189
B: 175
L: 126
Med: 126
Std: 91.2
R: 193
G: 113
B: 1
L: 60
Med: 60
Std: 11.4
R: 60
G: 61
B: 58
L: 126
Med: 126
Std: 91.2
R: 193
G: 113
B: 1
L: 122
Med: 122
Std: 21.5
R: 133
G: 120
B: 106
L: 126
Med: 126
Std: 91.2
R: 193
G: 113
B: 1
L: 65
Med: 65
Std: 11.8
R: 71
G: 64
B: 56 RL RS RC RB
Chromatic Properties
Condition:
Chromatic Properties
Condition:
Chromatic Properties
Condition:
Chromatic Properties
Condition:
L: 81
Med: 81
Std: 2.3
Un-aged
L: 37
Med: 37
Std: 3.1
R: 102
G: 79
B: 38
Un-aged
L: 15
Med: 15
Std: 2.4
R: 16
G: 16
B: 20
R: 52
G: 34
B: 9
Un-aged
L: 24
Med: 24
Std: 6.4
R: 25
G: 23
B: 26
Un-aged
Then, comparing different color of fillers and mastics, it can be stressed that mastic dominant colors were sensibly affected by filler chromatic properties.
And this fact could suggest that final road pavement colors could be principally affected by the chromatic characteristics of fine fraction aggregates.
Mastic
Mastic
Mastic
Mastic
MASTIC COLOR sensibly affected by filler chromatic properties (tone/shade and lightness value)

14. Preliminary Phase Conclusions13
Preliminary Phase Conclusions
Colored pavement useful to A) mitigate heat concentration/diffusion, thus UHI phenomenon; B) preserve landscape beauty,
could be realized with Synthetic Resin in substitution of organic bitumen.
Rheological Assessment
Concerning fine fraction portion (mastic):
Chromatic Assessment
Despite of different thermo-rheological behavior and the high-elastic attitude, resin demonstrated comparable, or even enhanced, stiffness and rutting resistance with respect to organic bitumen.
So, concerning the preliminary study conclusions, we can state that:
Colored pavement useful to mitigate heat concentration/diffusion, thus UHI phenomenon and – to preserve landscape beauty, could be realized with synthetic resin in substitution of organic bitumen. This principally because:
- despite of different thermo-rheological behavior and high-elastic attitude, resin demonstrated comparable, or even enhanced, rheological performance (especially at the high service temperatures)
- the simulated aging effects on resin did not seem to produce substantial alterations of its chromatic characteristics.
Fillers Tone/Shade and Lightness seemed to strongly affect final chromatic characteristics of mastics.
Long-term aging effect resulted negligible in terms of darkening effect/color alteration both for resin and final mastics.

15. Confirm the promising mechanical responses at the mixture scale.
Verify the real effectiveness of mastic color on the final pavement chromatic characteristics.
Further Perspectives of the Second Phase of the Study 14
Asses potential issues during mixture preparation and paving operations connected to.
the use of the resin
Analyze long-term chromatic responses of in-service road pavements.
Further Perspectives
(IN PROGRESS)
Evaluate the efficiency of final colored pavement in terms of UHI phenomena mitigation.
Concluding, further perspectives of the second phase of the study could be addressed to:
Heat Distribution Analysis
Thermographic assessment of colored asphalt mixtures for road pavements

16. Thank for your attention, and if anyone has any questions, I’ll be pleased to answer them.