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Contribution of solvents from road marking paints to tropospheric ozone formation

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Solventborne road marking paints are meaningful sources of Volatile Organic Compounds (VOCs), which under solar irradiation affect formation of tropospheric ozone, a significant pulmonary irritant and a key pollutant responsible for smog formation. Influence of particular VOCs on ground-level ozone formation potential, quantified in Maximum Incremental Reactivities (MIR), were used to calculate potential contribution of solvents from road marking paints used in Poland to tropospheric ozone formation. Based on 2014 data, limited only to roads administered by General Directorate for National Roads and Motorways (GDDKiA), emissions of VOCs from road marking paints in Poland were about 494 838 kg, which could lead to production of up to 1 003 187 kg of tropospheric ozone. If aromatic-free solventborne paints based on ester solvents, such as are commonly used in Western Europe, were utilised, VOC emissions would not be lowered, but potentially formed ground-level ozone could be limited by 50-70%. Much better choice from the perspective of environmental protection would be the use of waterborne road marking paints like those mandated in Scandinavia-elimination of up to 82% of the emitted VOCs and up to 95% of the potentially formed tropospheric ozone could be achieved.
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Budownictwo i Architektura 15(1) (2016) 7-18
Contribution of solvents from road marking paints
to tropospheric ozone formation
Tomasz E. Burghardt1, Anton Pashkevich2, Lidia Żakowska2
1 M. Swarovski GmbH, Industriestrasse 10, 3300 Amstetten, Austria,
e-mail tomasz.burghardt@swarco.com
2 Politechnika Krakowska im. Tadeusza Kościuszki, ul. Warszawska 24, 31-155 Kraków,
e-mail apashkevich@pk.edu.pl, lzakowsk@pk.edu.pl
Abstract: Solventborne road marking paints are meaningful sources of Volatile Or-
ganic Compounds (VOCs), which under solar irradiation affect formation of tropospheric
ozone, a significant pulmonary irritant and a key pollutant responsible for smog formation.
Influence of particular VOCs on ground-level ozone formation potential, quantified in
Maximum Incremental Reactivities (MIR), were used to calculate potential contribution of
solvents from road marking paints used in Poland to tropospheric ozone formation.
Based on 2014 data, limited only to roads administered by General Directorate for
National Roads and Motorways (GDDKiA), emissions of VOCs from road marking paints
in Poland were about 494 838 kg, which could lead to production of up to 1 003 187 kg of
tropospheric ozone.
If aromatic-free solventborne paints based on ester solvents, such as are commonly used
in Western Europe, were utilised, VOC emissions would not be lowered, but potentially
formed ground-level ozone could be limited by 50-70%. Much better choice from the per-
spective of environmental protection would be the use of waterborne road marking paints like
those mandated in Scandinavia elimination of up to 82% of the emitted VOCs and up to
95% of the potentially formed tropospheric ozone could be achieved.
Keywords: road marking, waterborne paint, solventborne paint, tropospheric ozone,
VOC, road safety, MIR, environmental protection.
1. Background
Horizontal road markings are essential safety feature on all modern roads. They are
quite frequently in the centre of drivers’ attention, providing information about the lateral
positioning of the vehicle and give guidance during driving.
The markings in Poland are generally divided into two types: thick-layer (1 mm or
thicker), comprising thermoplastic and coldplastic masses, and thin-layer (less than 1 mm)
comprising various paints with a possibility of using coldsprayplastic as well. Coldplastics
and thermoplastics shall not be covered in this analysis as they are considered solvent-free.
Plural-component systems based on epoxy or urethane technologies, which can be either
solventborne, water-dispersible, or solvent-free are not discussed, either. Properties of wa-
terborne and solventborne paints and their application characteristics were described else-
where [
1
].
Solventborne paints used for horizontal road markings are a meaningful source of
VOC emissions, which are capable of increasing the level of tropospheric ozone. Herein,
we estimated the amounts of VOCs emitted from road marking paints used in Poland and
calculated potential of the ozone formation from these VOCs. To demonstrate alternatives,
Tomasz E. Burghardt, Anton Pashkevich, Lidia Żakowska
8
the simulation was extended to include aromatic-free paints such as are at present used in
Western Europe and waterborne paints, which are the only type permitted in Scandinavia.
A notable limitation of our work is that only paints used for marking of roads admin-
istered by GDDKiA were included only about 19 000 km (out of ~250 000 km of the total
public paved roads network) due to difficulty of obtaining data from a plenitude of sources.
In our preceding work on this topic, we have concentrated on the city of Kraków and
demonstrated that road marking paints contribute to air pollution in that ecological disaster
area 18 254 kg of VOCs that could be adding up to 42 350 kg of tropospheric ozone [
2
].
The results of this analysis can be used by road administrators as an aid in selection of
road marking materials that are environmentally-friendly. Simultaneously, paint formula-
tors are being made aware that emissions of VOCs are not all equal.
1.1. Composition of road marking systems
Typical road marking paints consist of an organic polymeric resin (binder), inorganic
pigments and fillers, a package of additives, and a blend of organic solvents (for waterborne
paints mostly water). Classes of their components, with particular attention paid to sol-
vents, are discussed below.
1.1.1. Binders
Modern solventborne road marking paints are based on 100% acrylic binders. The
binders are produced by polymerisation of monomers like methyl acrylate, methyl methac-
rylate, ethyl acrylate, butyl acrylate, and similar. The resulting polymeric material is a solid
readily soluble in numerous organic solvents. Solventborne paints dry by simple evapora-
tion of solvents, which leaves a film consisting of the pigments and dried binder.
Waterborne paints are also based on 100% acrylic binders forming their polymeric
backbone. However, with the development of quick-set technology, the polymeric chains
were modified to contain monomers with moieties capable of acid-base chemistry [
3
]. Ad-
ditionally, binders for waterborne paints, which always are delivered in aqueous solutions,
require a base to assure protonation of the acidic moieties and a surfactant to keep the pol-
ymer suspended.
Modern waterborne paints furnish surprisingly quick drying and their application does
not require special equipment or knowledge, except normally expected differences associ-
ated with novel technology. A weakness of waterborne paints is washout resistance time,
which occurs after drying: A sudden rain on freshly applied waterborne paint may dissolve
it if the washout resistance time was not reached. Another weakness is slowing of drying at
marginal application conditions combining low temperature and high humidity. Quick-set
waterborne paints dry and cure due to simultaneous physical and chemical changes. They
are typically more durable than comparable solventborne paints, as we have measured and
recently reported [2].
1.1.2. Pigments and fillers
All white paints contain titanium dioxide. Even in yellow or blue paints, small amount
of titanium dioxide is included to give clean shades. Production of titanium dioxide is quite
complex. Titanium dioxide can be produced by chlorine or by sulphate process; comparison
of cradle-to-grave Life Cycle Assessment (LCA) for these processes demonstrated that
either one is very harmful for the environment, albeit in different aspects [
4
]. Indeed, an
LCA of road marking materials has shown that titanium dioxide, despite its quite low con-
tent, is the third major environmental impactor, lesser only than the impacts caused by the
production of binder and glass beads [
5
]. Surface treatment of titanium dioxide typically
Contribution of solvents from road marking paints to ... 9
the simulation was extended to include aromatic-free paints such as are at present used in
Western Europe and waterborne paints, which are the only type permitted in Scandinavia.
A notable limitation of our work is that only paints used for marking of roads admin-
istered by GDDKiA were included only about 19 000 km (out of ~250 000 km of the total
public paved roads network) due to difficulty of obtaining data from a plenitude of sources.
In our preceding work on this topic, we have concentrated on the city of Kraków and
demonstrated that road marking paints contribute to air pollution in that ecological disaster
area 18 254 kg of VOCs that could be adding up to 42 350 kg of tropospheric ozone [
2
].
The results of this analysis can be used by road administrators as an aid in selection of
road marking materials that are environmentally-friendly. Simultaneously, paint formula-
tors are being made aware that emissions of VOCs are not all equal.
1.1. Composition of road marking systems
Typical road marking paints consist of an organic polymeric resin (binder), inorganic
pigments and fillers, a package of additives, and a blend of organic solvents (for waterborne
paints mostly water). Classes of their components, with particular attention paid to sol-
vents, are discussed below.
1.1.1. Binders
Modern solventborne road marking paints are based on 100% acrylic binders. The
binders are produced by polymerisation of monomers like methyl acrylate, methyl methac-
rylate, ethyl acrylate, butyl acrylate, and similar. The resulting polymeric material is a solid
readily soluble in numerous organic solvents. Solventborne paints dry by simple evapora-
tion of solvents, which leaves a film consisting of the pigments and dried binder.
Waterborne paints are also based on 100% acrylic binders forming their polymeric
backbone. However, with the development of quick-set technology, the polymeric chains
were modified to contain monomers with moieties capable of acid-base chemistry [
3
]. Ad-
ditionally, binders for waterborne paints, which always are delivered in aqueous solutions,
require a base to assure protonation of the acidic moieties and a surfactant to keep the pol-
ymer suspended.
Modern waterborne paints furnish surprisingly quick drying and their application does
not require special equipment or knowledge, except normally expected differences associ-
ated with novel technology. A weakness of waterborne paints is washout resistance time,
which occurs after drying: A sudden rain on freshly applied waterborne paint may dissolve
it if the washout resistance time was not reached. Another weakness is slowing of drying at
marginal application conditions combining low temperature and high humidity. Quick-set
waterborne paints dry and cure due to simultaneous physical and chemical changes. They
are typically more durable than comparable solventborne paints, as we have measured and
recently reported [2].
1.1.2. Pigments and fillers
All white paints contain titanium dioxide. Even in yellow or blue paints, small amount
of titanium dioxide is included to give clean shades. Production of titanium dioxide is quite
complex. Titanium dioxide can be produced by chlorine or by sulphate process; comparison
of cradle-to-grave Life Cycle Assessment (LCA) for these processes demonstrated that
either one is very harmful for the environment, albeit in different aspects [
4
]. Indeed, an
LCA of road marking materials has shown that titanium dioxide, despite its quite low con-
tent, is the third major environmental impactor, lesser only than the impacts caused by the
production of binder and glass beads [
5
]. Surface treatment of titanium dioxide typically
consists of inorganic and organic chemicals and can vary greatly between grades and manu-
facturers; it plays profound role in stability of waterborne road marking paints.
Amongst eight known titanium dioxide polymorphs, two are of importance: rutile and
anatase. In paints, rutile is used, because it has higher refractive index: 2.7, as compared to
only 2.5 for anatase. In titanium dioxide crystal structure, each titanium atom is surrounded
by six oxygen atoms in octahedral arrangement with mostly regular structure. In more
closely packed rutile structure, the octahedra are turned through 9 with a twist of 45°
from one layer to the next. In anatase, the twists are missing, which negatively influences
packing and was reported to reduce the refractive index. Anatase is occasionally added to
paints to improve their durability and lower raw materials expense.
Of course, to prepare colours other than white, appropriate organic pigments are used.
In some cases, a small amount of inorganic colour pigments like iron oxide is also added to
achieve the desired paint properties.
Majority of the volume of paint is calcium carbonate readily available harmless in-
expensive filler. Some paints, especially those designed for special purposes, can also con-
tain other fillers. Paints ought to be devoid of any pigments or fillers containing chromium,
lead, or other heavy metals.
1.1.3. Additives
Amongst other raw materials for paint production, there is a plethora of additives,
which are necessary to assure paint processing and stability. Appropriate selection of addi-
tives plays the most profound role in all paints and is quite frequently the major differentia-
tor between equivalent formulations from different manufacturers.
Amongst additives, dispersants, most of the time based on functionalised acrylates,
play critical role not only in proper dispersing of pigment particles, but also in preventing
their flocculation and settling.
In-can stability is achieved by the use of thickeners and anti-settling additives, which
prevent separation of pigment particles from the binder and their precipitation. Organic and
inorganic, naturally-derived and engineered compounds are available and suitable.
Defoamers are used to release any air bubbles formed during paint processing and ap-
plication. For road marking paints, it is critical that the defoamers remain compatible with
glass beads, which meaningfully limits their selection.
Plasticisers that assure appropriate flexibility of the dried film are frequently added as
some paints might be too brittle to withstand impact caused by tyres and snow ploughs. It is
important that phthalate-free plasticisers are utilised, because of environmental and health
concerns.
For waterborne paints, one additionally can use biocides, surfactants, wetting agents,
grinding aids, and other materials. However, the most important is coalescent: With the
current technology, it is not possible to prepare a successful waterborne paint without a
coalescent or an alternate molecule that acts as such. Coalescents are small molecules that
“bring together” drying polymeric chains and thus furnish smooth crack-free surface.
1.1.4. Solvents
Solvents are necessary to make the paint liquid. Amongst the numerous available ma-
terials, paint manufacturers select only a few that show the desired properties, like speed of
evaporation, capability of penetration of the surface cracks to improve durability and adhe-
sion of the paint, and price. Selected properties of solvents commonly used in road marking
paints are given in Table 1 and their chemical structures are provided in Fig. 1. Solubility
parameters describing a sphere of solubility, based on like-dissolves-like principle, were
Tomasz E. Burghardt, Anton Pashkevich, Lidia Żakowska
10
developed by Hansen and bear his name [
6
]. The sphere can be used to predict solubility of
different materials in case of road marking paints such information is needed to properly
dissolve the binder and simultaneously to prepare paints with good adhesion to bituminous
and concrete surfaces.
Toluene is a commonly used aromatic solvent; its moderate evaporation rate is advan-
tageous in prevention of forming skin and essentially uniform dry-through of the forming
film. Toluene has very high dispersion forces solubility parameter (δd), which along with
low polarity (δp) and low hydrogen bonding capability (δH) gives it the capability of pene-
trating surface cracks and even dissolving some of typical oily contaminations present on
road surface. Hence, the use of toluene is favoured by the paint formulators and applicators.
However, toluene is quite harmful for the environment and as such it is effectively banned
in Western Europe. In Poland, its amount is limited to 8% of the total road marking paint
formulation [
7
]. Toluene is not a carcinogen [
8
], but it is classified as reproductive toxicant
and targets organs like kidneys, liver, and the central nervous system. Due to its solubility
in lipids, absorption through dermal exposure is as likely as inhalation and equally harmful.
A recent field assessment of road marking crews’ exposure to toluene has shown that the
permissible concentrations were not exceeded [
9
].
Other common solvents, either esters or ketones, generally are somewhat more polar
and are capable of better forming hydrogen bonding. Hence, while their capability of dis-
solving acrylic resin is not affected, they are somewhat less likely to penetrate surface
cracks and adhere to oily asphalt. Their evaporation rates depend on the carbon chain length
and functionality, so selection of appropriate blends to achieve paint dry-through without
skin formation is quite easy. Generally, ester solvents are considered in the industry as
better, due to their lower toxicity and good affinity for resins.
Acetone, with an exceptionally high evaporation rate and high solubility parameters is
barely suitable for road marking paints, because excessively fast drying of the paint would
prevent good adhesion, particularly when road surface temperatures are high. However,
acetone has miniscule toxicity and its ozone formation potential is so low that it is consid-
ered in the United States an ‘exempt solvent’, not counted as VOC [
10
].
Table 1. Properties of selected solvents commonly used for road marking paints
Name
Density
[g/cm³]
Evaporation
rate(a)
Boiling
point [°C]
δd
δp
δH
Toluene
0.87
200
110
18.0
1.4
1.4
1-methoxypropan-2-yl acetate
0.97
33
146
15.6
5.6
9.8
Butyl acetate
0.88
100
126
15.8
3.7
6.3
Methyl isobutyl ketone
0.80
166
116
15.3
6.1
4.1
Methyl ethyl ketone
0.81
390
80
16.0
9.0
5.1
Acetone
0.79
560
56
15.5
10.4
7.0
(a) Relative to n-butyl acetate, assumed as 100. (b) Hansen solubility parameters are given in the units of
MPa1/2: δd denotes dispersive forced, δp dipolar intermolecular forces, and δH hydrogen bonding.
O
Methyl isobutyl ketone
O
O
Ethyl acetate
O
O
O
Butyl acetate
Acetone
O
O
O
O
1-methoxypropan-2-yl acetate
TolueneMethyl ethyl ketone
Fig. 1. Chemical structures of common solvents
Contribution of solvents from road marking paints to ... 11
developed by Hansen and bear his name [
6
]. The sphere can be used to predict solubility of
different materials in case of road marking paints such information is needed to properly
dissolve the binder and simultaneously to prepare paints with good adhesion to bituminous
and concrete surfaces.
Toluene is a commonly used aromatic solvent; its moderate evaporation rate is advan-
tageous in prevention of forming skin and essentially uniform dry-through of the forming
film. Toluene has very high dispersion forces solubility parameter (δd), which along with
low polarity (δp) and low hydrogen bonding capability (δH) gives it the capability of pene-
trating surface cracks and even dissolving some of typical oily contaminations present on
road surface. Hence, the use of toluene is favoured by the paint formulators and applicators.
However, toluene is quite harmful for the environment and as such it is effectively banned
in Western Europe. In Poland, its amount is limited to 8% of the total road marking paint
formulation [
7
]. Toluene is not a carcinogen [
8
], but it is classified as reproductive toxicant
and targets organs like kidneys, liver, and the central nervous system. Due to its solubility
in lipids, absorption through dermal exposure is as likely as inhalation and equally harmful.
A recent field assessment of road marking crews’ exposure to toluene has shown that the
permissible concentrations were not exceeded [
9
].
Other common solvents, either esters or ketones, generally are somewhat more polar
and are capable of better forming hydrogen bonding. Hence, while their capability of dis-
solving acrylic resin is not affected, they are somewhat less likely to penetrate surface
cracks and adhere to oily asphalt. Their evaporation rates depend on the carbon chain length
and functionality, so selection of appropriate blends to achieve paint dry-through without
skin formation is quite easy. Generally, ester solvents are considered in the industry as
better, due to their lower toxicity and good affinity for resins.
Acetone, with an exceptionally high evaporation rate and high solubility parameters is
barely suitable for road marking paints, because excessively fast drying of the paint would
prevent good adhesion, particularly when road surface temperatures are high. However,
acetone has miniscule toxicity and its ozone formation potential is so low that it is consid-
ered in the United States an ‘exempt solvent’, not counted as VOC [
10
].
Table 1. Properties of selected solvents commonly used for road marking paints
Name
Density
[g/cm³]
Evaporation
rate(a)
Boiling
point [°C]
Hansen solubility parameters(b)
δd
δp
δH
Toluene
0.87
200
110
18.0
1.4
1.4
1-methoxypropan-2-yl acetate
0.97
33
146
15.6
5.6
9.8
Butyl acetate
0.88
100
126
15.8
3.7
6.3
Methyl isobutyl ketone
0.80
166
116
15.3
6.1
4.1
Methyl ethyl ketone
0.81
390
80
16.0
9.0
5.1
Acetone
0.79
560
56
15.5
10.4
7.0
(a) Relative to n-butyl acetate, assumed as 100. (b) Hansen solubility parameters are given in the units of
MPa1/2: δd denotes dispersive forced, δp dipolar intermolecular forces, and δH hydrogen bonding.
O
Methyl isobutyl ketone
O
O
Ethyl acetate
O
O
O
Butyl acetate
Acetone
O
O
O
O
1-methoxypropan-2-yl acetate
TolueneMethyl ethyl ketone
Fig. 1. Chemical structures of common solvents
Properties of volatiles present in waterborne road marking paints are given in Table 2:
water is the main solvent. Water, with its slow evaporation, would normally translate to
very slowly drying paints; fortuitously, modern waterborne paints employ another drying
and curing mechanism, which permits for their exceptionally quick drying [3]. The same
mechanism allows for application of films reaching even 1200 µm without unacceptable
slowing of drying [1].
Amongst the volatiles, one must list ammonium hydroxide, which is the base neces-
sary to keep the paints stable before application, decomposes to ammonia, which quickly
evaporates upon application, causing drop in pH and thus paint drying and curing. Ammo-
nia is an irritant, so several commercial ammonia-free binders have been devised; unfortu-
nately, these binders do not permit yet to achieve the desired quick drying of applied road
marking. A small amount of ethyl alcohol is added to the paint as a processing aid and also
to augment freeze-thaw stability.
Another volatile, albeit evaporating extremely slowly, is Texanol®, a C12 hydroxyes-
ters mixture that acts as coalescent. Chemical structure of Texanol® is provided in Fig. 2;
the ratio of the two esters is not disclosed by either the original manufacturer (Eastman
Chemical, of Kingsport, Tennessee, U. S. A.) or numerous makers of generics.
Table 2. Properties of volatile materials used for waterborne road marking paints
Name
Density
[g/cm³]
Evaporation
rate(a)
Boiling
point [°C]
Hansen solubility parameters(b)
δd
δp
δH
Ammonium hydroxide
0.73
n/a
37
n/a
n/a
n/a
Ethanol
0.79
165
78
15.8
8.8
19.4
Texanol®
0.95
0.002
255
7.4
3.0
4.8
Water
1.00
30
100
7.6
7.8
20.7
(a) Relative to n-butyl acetate, assumed as 100. (b) Hansen solubility parameters are given in the units of
MPa1/2: δd denotes dispersive forced, δp dipolar intermolecular forces, and δH hydrogen bonding.
O
O
OH
OH
O O
+
Fig. 2. Chemical structure of Texanol®
1.1.5. Glass beads
Glass beads are used as reflective elements and are inalienable component of road
marking systems. Beads of various refractive indices and sizes ranging in diameter from
about 100 µm to 2 mm are commonly used. Incorporation of anti-skid particles in glass
beads packages assures proper skid resistance, necessary for safety during wet conditions.
The selection of glass beads is critical to achieve the optimum performance of the ap-
plied systems as they not only provide retroreflectivity, but also protect the paints from
abrasion caused by the vehicular traffic. Appropriate embedment of glass beads is neces-
sary to achieve retroreflectivity [
11
], so the application crews must adjust the beads flow to
obtain the best results. Mismatch between glass surface coating and the road marking paint
can lead to significant lowering of beads-paint adhesion, causing premature failures.
High-performance glass beads can furnish very high retroreflection, which can exceed
1000 mcd/m²/lx while the required initial minimum is only 200 mcd/m²/lx. Numerous re-
ports demonstrate positive impression from people who drive on roads with high retrore-
Tomasz E. Burghardt, Anton Pashkevich, Lidia Żakowska
12
flectivity of the horizontal markings [
12
][
13
], even though some reports show no direct
correlation between retroreflectivity and road safety [
14
]. Definitely, elderly drivers bene-
fits from higher retroreflection [
15
]. It is also very likely that the improved aesthetics asso-
ciated with clear and well-marked roads would lead to increased safety [
16
][
17
].
1.2. Tropospheric ozone
Ozone, a tri-molecular allotrope of oxygen, is naturally occurring and forms in the
atmosphere during lightning. Majority of ozone is found in the lower stratosphere, where it
plays critical role in absorption of ultraviolet rays and thus protection of life on Earth.
However, ozone is also present in the troposphere. Some of it is a result of natural atmos-
pheric mixing, but majority has been reported to be formed as a result of photolytic decom-
position of nitrogen oxide (NO2), according to a general scheme shown in eq. 1 [
18
].
(1) NO
2
hNO + O•
(2) O• + O
2
O
3
(3) NO + O
3
NO
2
+ O
2
k
1
k
2
k
3
(Step) Reaction Reaction rate
(1)
In eq. 1, steps (1) and (2) lead to ozone generation, while step (3) accounts for ozone
depletion. Hence, equilibrium shown in eq. 2 forms.
 
 
21
3
3
NO
ONO
k
k
(2)
Ozone is one of the key components of smog. It is a severe respiratory system irritant;
its negative effects on human health are well-documented [
19
] and numerous premature
deaths are attributed to its presence at the ground level [
20
]. Concerning is the fact that
higher concentration of ozone in cities lead to prolonged and repeated exposure of people
who are already exposed to a plethora of other pollutants, which might exaggerate its harm-
fulness. Even though Poland does not suffer from tropospheric ozone pollution as extreme
as, for example, Northern Italy, the concentrations are still sufficiently high to cause dam-
age to certain sensitive plants [
21
].
1.3. Maximum Incremental Reactivity (MIR)
All of the VOCs undergo decomposition in the atmosphere via photolytic pathways,
as was first reported by Leighton [
22
]. Elucidation of the mechanism and confirmation that
the VOCs affect the equilibrium shown in eq. 2 was done by Crutzen [
23
]. Laboratory
experiments and theoretical calculations have demonstrated very significant differences
between ozone formation that could be attributed to various VOCs, as was reported by
Carter and Atkinson [
24
]. The differences are caused by chemical moieties formed during
decomposition, which in can be re-introduced times into the ozone formation reactions.
VOC-influenced ozone formation depends on many factors, such as concentrations in
the above-defined equilibrium, presence of other pollutants, temperature, irradiation level,
etc. To quantify these effects, Carter defined maximum incremental reactivity as the
amount of additional ozone formation resulting from the addition of a small amount of the
compound to the system in which ozone is formed, divided by the amount of compound
Contribution of solvents from road marking paints to ... 13
flectivity of the horizontal markings [
12
][
13
], even though some reports show no direct
correlation between retroreflectivity and road safety [
14
]. Definitely, elderly drivers bene-
fits from higher retroreflection [
15
]. It is also very likely that the improved aesthetics asso-
ciated with clear and well-marked roads would lead to increased safety [
16
][
17
].
1.2. Tropospheric ozone
Ozone, a tri-molecular allotrope of oxygen, is naturally occurring and forms in the
atmosphere during lightning. Majority of ozone is found in the lower stratosphere, where it
plays critical role in absorption of ultraviolet rays and thus protection of life on Earth.
However, ozone is also present in the troposphere. Some of it is a result of natural atmos-
pheric mixing, but majority has been reported to be formed as a result of photolytic decom-
position of nitrogen oxide (NO2), according to a general scheme shown in eq. 1 [
18
].
(1) NO
2
hNO + O•
(2) O• + O
2
O
3
(3) NO + O
3
NO
2
+ O
2
k
1
k
2
k
3
(Step) Reaction Reaction rate
(1)
In eq. 1, steps (1) and (2) lead to ozone generation, while step (3) accounts for ozone
depletion. Hence, equilibrium shown in eq. 2 forms.
 
 
21
3
3
NO
ONO
k
k
(2)
Ozone is one of the key components of smog. It is a severe respiratory system irritant;
its negative effects on human health are well-documented [
19
] and numerous premature
deaths are attributed to its presence at the ground level [
20
]. Concerning is the fact that
higher concentration of ozone in cities lead to prolonged and repeated exposure of people
who are already exposed to a plethora of other pollutants, which might exaggerate its harm-
fulness. Even though Poland does not suffer from tropospheric ozone pollution as extreme
as, for example, Northern Italy, the concentrations are still sufficiently high to cause dam-
age to certain sensitive plants [
21
].
1.3. Maximum Incremental Reactivity (MIR)
All of the VOCs undergo decomposition in the atmosphere via photolytic pathways,
as was first reported by Leighton [
22
]. Elucidation of the mechanism and confirmation that
the VOCs affect the equilibrium shown in eq. 2 was done by Crutzen [
23
]. Laboratory
experiments and theoretical calculations have demonstrated very significant differences
between ozone formation that could be attributed to various VOCs, as was reported by
Carter and Atkinson [
24
]. The differences are caused by chemical moieties formed during
decomposition, which in can be re-introduced times into the ozone formation reactions.
VOC-influenced ozone formation depends on many factors, such as concentrations in
the above-defined equilibrium, presence of other pollutants, temperature, irradiation level,
etc. To quantify these effects, Carter defined maximum incremental reactivity as the
amount of additional ozone formation resulting from the addition of a small amount of the
compound to the system in which ozone is formed, divided by the amount of compound
added” and devised for California Air Quality Management District a straightforward pro-
tocol and a measurement scale [
25
]. The conditions used by Carter assume the worst-case
scenario of high insolation (35° North) and unlimited NO2 supply. The studies were later
examined and confirmed by several researchers [
26
]; field measurements of pollution
plumes further confirmed the theoretical and laboratory analyses [
27
]. Subsequent adjust-
ments of the calculated and published MIR values were done as new data and methodolo-
gies became available [
28
], but the general trends remain in force.
2. Results and discussion
2.1. Methodology
The use of MIR, which are expressed in the unit of grams of potentially formed ozone
per gram of VOC made the calculations very simple and straightforward [25]. MIR values
published in California Code of Regulations, Title 17, Chapter 8, §94700 were used.
To perform the calculations, results from a query for public information to GDDKiA
were analysed [
29
]. The response provided the surface area that was painted and in some
cases also the specific paint: in 2014, 3 436 371 was marked. To obtain the mass
amount, an assumption of a typical thin-layer application of 600 g/m² (400 µm) wet film
was made, yielding paints consumption of 2 061 822 kg. Amongst other necessary assump-
tions, in cases where multi-year contracts were in force, the provided amounts were divided
by the number of years to give an approximate annual usage. In some cases, where the
specific paint was not listed, solvent composition being a weighted average of other paints
was used.
The solvents compositions were taken from publically available Safety Data Sheets.
To avoid providing excessive data details that would obscure the main point of our work,
we have analysed the solvents compositions and combined them into two categories: tolu-
ene plus esters and toluene plus ketones. The solvent packages were idealised, because the
Safety Data Sheets do not list exact compositions and chromatographic analyses for posi-
tive solvents identification was beyond the scope of our work.
2.2. Solvent compositions and emissions
Composition of the volatiles from these two paints categories and alternative paints
are shown in Table 3. It should be noted that the compositions of solventborne paints are
somewhat different as used for model paints in case of our paper concentrating on Kraków
[2], because of the aforementioned approximation.
For our calculations, all of the paints were assumed to contain 24% of solvents, which
upon application evaporate to become VOCs. In case of waterborne paint, the VOC were
assumed to be 5%, with the remaining 19% being water. Considerations regarding VOC of
the coalescent were discussed elsewhere [2].
In Table 4 are listed the data obtained from GDDKiA regarding the painted surfaces,
which we broke down based on the paints composition [29]. Aromatic-free and waterborne
paints were not listed amongst ordered by applicators. Total emitted VOCs and the calcu-
lated maximum amounts of formed tropospheric ozone based on the MIR are provided.
Tomasz E. Burghardt, Anton Pashkevich, Lidia Żakowska
14
Table 3. Idealised composition of volatiles of the analysed paints and their MIR
Solvent
MIR
Toluene - ketones
Toluene - esters
Esters
Waterborne
Toluene
4.00
8.0%
8.0%
Methyl isobutyl ketone
3.88
8.0%
Methyl ethyl ketone
1.48
8.0%
Butyl acetate
0.83
8.0%
12.0%
Ethyl acetate
0.63
8.0%
8.0%
1-methoxypropan-2-yl acetate
1.70
4.0%
Texanol®
0.81
3.5%
Ethanol
1.53
0.5%
Ammonium hydroxide
0.00
1.0%
Water
0.00
19.0%
Table 4. Tender data from GDDKiA: solvents compositions and emissions
Solvents package:
Toluene - ketones
Toluene - esters
Marking area [m²]
547 985
2 888 386
Paint amount [kg]
328 791
1 733 032
Maximum ozone [kg] formed per 1 kg of paint
0.749
0.437
Maximum ozone [kg] formed per painted 1
0.449
0.262
Total emitted VOC [kg]
78 910
415 928
Total potentially formed tropospheric ozone [kg]
246 199
756 988
As shown in Table 4, the amount of potentially produced ozone very significantly ex-
ceeds the emitted VOCs in all cases, mostly because of high MIR of toluene and methyl
isobutyl ketone. The paints containing ketone solvents are meaningfully less environmen-
tally friendly as compared to those where esters are used. Fortunately for our environment,
the paints containing ketones appear to be less popular amongst applicators.
In case of paints that contain toluene and ketone solvents, up to 0.749 kg of ground-
level ozone could be formed from each kilogram of paint applied (0.449 kg per 1 of
painted surface). At annual use of 328 791 kg, 78 910 kg of VOCs are emitted to the at-
mosphere, which could lead to the formation of up to 246 199 kg of tropospheric ozone.
With paints where esters are used along toluene, the ozone formation potential is lower, at
0.437 kg per 1 kg of paint (0.262 kg per 1 of marked surface). Therefore, the annual
usage of 1 733 032 kg translates to VOC emissions of 415 928 kg and potentially up to
756 988 kg of tropospheric ozone produced.
Overall, from the annual thin-layer marking of roads administered by GDDKiA, ap-
proximately 494 838 kg of VOCs are emitted to the atmosphere, leading to potential for-
mation of up to 1 003 187 kg of ozone.
The supply of NO2 necessary for ozone formation is furnished directly at the road
marking application sites by vehicular traffic traffic jams caused by marking activities do
increase the NO2 availability. Measurements correlating vehicular traffic, nitrogen oxides
concentration, and tropospheric ozone were reported over 20 years ago [
30
].
Insolation in Poland (50° North) is meaningfully lower as compared to the conditions
used for obtaining MIR (35° North), which is a significant abating factor making the above
maxima unlikely to be reached in our country. Furthermore, extreme temperatures are not
frequent and meaningful part of road marking is done either after sunset or in autumn when
the insolation is nil or marginal. However, one has to remember that even if the solvents do
not decompose in the troposphere and not cause increased ozone formation, they migrate to
stratosphere, where they cause more harm to the environment.
Contribution of solvents from road marking paints to ... 15
Table 3. Idealised composition of volatiles of the analysed paints and their MIR
Solvent
MIR
Toluene - ketones
Toluene - esters
Esters
Waterborne
Toluene
4.00
8.0%
8.0%
Methyl isobutyl ketone
3.88
8.0%
Methyl ethyl ketone
1.48
8.0%
Butyl acetate
0.83
8.0%
12.0%
Ethyl acetate
0.63
8.0%
8.0%
1-methoxypropan-2-yl acetate
1.70
4.0%
Texanol®
0.81
3.5%
Ethanol
1.53
0.5%
Ammonium hydroxide
0.00
1.0%
Water
0.00
19.0%
Table 4. Tender data from GDDKiA: solvents compositions and emissions
Solvents package:
Toluene - ketones
Toluene - esters
Marking area [m²]
547 985
2 888 386
Paint amount [kg]
328 791
1 733 032
Maximum ozone [kg] formed per 1 kg of paint
0.749
0.437
Maximum ozone [kg] formed per painted 1
0.449
0.262
Total emitted VOC [kg]
78 910
415 928
Total potentially formed tropospheric ozone [kg]
246 199
756 988
As shown in Table 4, the amount of potentially produced ozone very significantly ex-
ceeds the emitted VOCs in all cases, mostly because of high MIR of toluene and methyl
isobutyl ketone. The paints containing ketone solvents are meaningfully less environmen-
tally friendly as compared to those where esters are used. Fortunately for our environment,
the paints containing ketones appear to be less popular amongst applicators.
In case of paints that contain toluene and ketone solvents, up to 0.749 kg of ground-
level ozone could be formed from each kilogram of paint applied (0.449 kg per 1 of
painted surface). At annual use of 328 791 kg, 78 910 kg of VOCs are emitted to the at-
mosphere, which could lead to the formation of up to 246 199 kg of tropospheric ozone.
With paints where esters are used along toluene, the ozone formation potential is lower, at
0.437 kg per 1 kg of paint (0.262 kg per 1 of marked surface). Therefore, the annual
usage of 1 733 032 kg translates to VOC emissions of 415 928 kg and potentially up to
756 988 kg of tropospheric ozone produced.
Overall, from the annual thin-layer marking of roads administered by GDDKiA, ap-
proximately 494 838 kg of VOCs are emitted to the atmosphere, leading to potential for-
mation of up to 1 003 187 kg of ozone.
The supply of NO2 necessary for ozone formation is furnished directly at the road
marking application sites by vehicular traffic traffic jams caused by marking activities do
increase the NO2 availability. Measurements correlating vehicular traffic, nitrogen oxides
concentration, and tropospheric ozone were reported over 20 years ago [
30
].
Insolation in Poland (50° North) is meaningfully lower as compared to the conditions
used for obtaining MIR (35° North), which is a significant abating factor making the above
maxima unlikely to be reached in our country. Furthermore, extreme temperatures are not
frequent and meaningful part of road marking is done either after sunset or in autumn when
the insolation is nil or marginal. However, one has to remember that even if the solvents do
not decompose in the troposphere and not cause increased ozone formation, they migrate to
stratosphere, where they cause more harm to the environment.
2.3. Environmentally-friendly alternatives
One of our goals was presenting readily available alternatives to the currently used
systems. Hence, solvent packages of a toluene-free ester-based solventborne road marking
paint and a waterborne paint were included in Table 3. We do not include a 0 VOC” paint
according to the United States rules, because such paint, despite very low impact on the
formation of tropospheric ozone [
31
], would be a poor alternative on our roads and could
be prohibitively expensive.
In Table 5, we are providing results for the same volumes of paints that were ordered
for road marking by GDDKiA, but assuming two readily available alternatives: Aromatic-
free ester-based solventborne paint and a waterborne paint. The savings of our natural re-
sources could be enormous, as visualised in Fig. 3, where various emissions scenarios are
compared. Assuming that only ester solvents were used (without toluene or methyl isobutyl
ketone), the amount of potentially formed ozone could be lowered by approximately 50-
71%. Limiting the emissions of VOC by 82% and lowering potential of tropospheric ozone
formation by 83-95% could be achieved if all thin-layer marking were done with a water-
borne paint.
Table 5. Emissions from alternative paints
Solvents package:
Esters
Waterborne
Maximum ozone [kg] formed per 1 kg of paint
0.218
0.036
Maximum ozone [kg] formed per painted 1
0.131
0.022
Total emitted VOC [kg] in case of full conversion
494 837
87 627
Total potential formed ozone [kg] in case of full conversion
449 447
74 226
Potential of lowering VOC emissions
0%
-82%
Potential for lowering tropospheric ozone formation
-50% -71%
-83% -95%
Fig. 3. Emissions scenarios with various solvent packages
Tomasz E. Burghardt, Anton Pashkevich, Lidia Żakowska
16
3. Conclusions
This analysis of road marking paints used in Poland has demonstrated profound influ-
ence of their solvent packages on tropospheric ozone formation potential. The calculations
have shown that 2 061 823 kg of paints used for thin-layer markings of roads administered
by GDDKiA emit to the atmosphere 494 838 kg of VOCs capable of producing up to
1 003 187 kg of tropospheric ozone. While lowering the VOC emissions would require
switch to a technology of waterborne paints, which is still a novelty in Poland, significant
potential for tropospheric ozone formation could be achieved with simple adjustments of
solvent blends within the existing technology. Solventborne paints with carefully selected
solvents could lead to lowering of the potentially formed tropospheric ozone by about 50%.
However, better choice would be the use of waterborne paints, which emit up to 79% VOCs
less and their solvents have ozone formation potential lower by 83-95%.
The results provided herein do not include paints ordered by local road authorities.
These amounts are significant, because local roads constitute about 90% of total paved
roads in Poland. In fact, an environmental analysis report has estimated the use of sol-
ventborne road marking paints in Poland in 2006 at 21 308 000 kg, with expected signifi-
cant growth [
32
].
In comparison with other anthropogenic emissions, such as vehicular or industrial,
pollution caused by road marking paints is insignificant. However, every little effort that
can help our environment should not be abandoned, especially if more sustainable alterna-
tives are readily available.
We have provided in this work a tool to road administrators in selecting environmen-
tally-friendly sustainable solutions and simultaneously gave information to paint formula-
tors to select materials with least impact on the health of our planet.
References
1
Babić D., Burghardt TE., Babić D. Application and Characteristics of Waterborne Road Marking
Paint. International Journal for Traffic and Transport Engineering 5 (2015) 150-169.
2
Burghardt TE., Pashkevich A., Żakowska L. Influence of Volatile Organic Compounds Emissions
from Road Marking Paints on Ground-Level Ozone Formation. Case Study of Kraków, Poland.
Transportation Research Procedia (2016) in press.
3
Clinnin DD., Heiber WG., Lewarchik RJ. Fast dry waterborne traffic marking paint. United States
Patent 5,340,870.
4
Reck E., Richards M. Titanium dioxide - Manufacture, environment, and life cycle analysis: The
tioxide experience. Surface Coatings International 80 (1997) 568-572.
5
Kheradmand H. Life Cycle Assessment. Road Marking Technologies Eco-Profile. Intertraffic,
Amsterdam, 2012.
6
Hansen CM. The three dimensional solubility parameter and solvent diffusion coefficient. Copen-
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IBDiM (Instytut Badawczy Dróg i Mostów / Road and Bridge Research Institute). Warunki
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32-40.
10
Per United States Code of Federal Regulations, Chapter 40, §51.100(s).
Contribution of solvents from road marking paints to ... 17
3. Conclusions
This analysis of road marking paints used in Poland has demonstrated profound influ-
ence of their solvent packages on tropospheric ozone formation potential. The calculations
have shown that 2 061 823 kg of paints used for thin-layer markings of roads administered
by GDDKiA emit to the atmosphere 494 838 kg of VOCs capable of producing up to
1 003 187 kg of tropospheric ozone. While lowering the VOC emissions would require
switch to a technology of waterborne paints, which is still a novelty in Poland, significant
potential for tropospheric ozone formation could be achieved with simple adjustments of
solvent blends within the existing technology. Solventborne paints with carefully selected
solvents could lead to lowering of the potentially formed tropospheric ozone by about 50%.
However, better choice would be the use of waterborne paints, which emit up to 79% VOCs
less and their solvents have ozone formation potential lower by 83-95%.
The results provided herein do not include paints ordered by local road authorities.
These amounts are significant, because local roads constitute about 90% of total paved
roads in Poland. In fact, an environmental analysis report has estimated the use of sol-
ventborne road marking paints in Poland in 2006 at 21 308 000 kg, with expected signifi-
cant growth [
32
].
In comparison with other anthropogenic emissions, such as vehicular or industrial,
pollution caused by road marking paints is insignificant. However, every little effort that
can help our environment should not be abandoned, especially if more sustainable alterna-
tives are readily available.
We have provided in this work a tool to road administrators in selecting environmen-
tally-friendly sustainable solutions and simultaneously gave information to paint formula-
tors to select materials with least impact on the health of our planet.
References
1
Babić D., Burghardt TE., Babić D. Application and Characteristics of Waterborne Road Marking
Paint. International Journal for Traffic and Transport Engineering 5 (2015) 150-169.
2
Burghardt TE., Pashkevich A., Żakowska L. Influence of Volatile Organic Compounds Emissions
from Road Marking Paints on Ground-Level Ozone Formation. Case Study of Kraków, Poland.
Transportation Research Procedia (2016) in press.
3
Clinnin DD., Heiber WG., Lewarchik RJ. Fast dry waterborne traffic marking paint. United States
Patent 5,340,870.
4
Reck E., Richards M. Titanium dioxide - Manufacture, environment, and life cycle analysis: The
tioxide experience. Surface Coatings International 80 (1997) 568-572.
5
Kheradmand H. Life Cycle Assessment. Road Marking Technologies Eco-Profile. Intertraffic,
Amsterdam, 2012.
6
Hansen CM. The three dimensional solubility parameter and solvent diffusion coefficient. Copen-
hagen, Denmark: Danish Technical Press (1967).
7
IBDiM (Instytut Badawczy Dróg i Mostów / Road and Bridge Research Institute). Warunki
Techniczne. Poziome znakowanie dróg. POD-2006. Seria „I” - Informacje, Instrukcje. Warszawa,
2007.
8
McMichael AJ. Carcinogenicity of benzene, toluene and xylene: epidemiological and experi-
mental evidence. IARC Scientific Publication 85 (1988) 3-18.
9
Szpakowska-Kozikowska E., Mniszek W. Exposure assessment of workers during road surface
marking. Zeszyty Naukowe Wyższej Szkoły Zarządzania Ochroną Pracy w Katowicach 1 (2014)
32-40.
10
Per United States Code of Federal Regulations, Chapter 40, §51.100(s).
11
Grosges T. Retro-reflection of glass beads for traffic road stripe paints. Optical Materials 30
(2008) 1549-1554.
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Carnaby B. Poor road markings contribute to crash rates. Australasian Road Safety Research
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driving simulator evaluation. Transportation Research Part F: Traffic Psychology and Behaviour
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Żakowska L. The effect of environmental and design parameters on subjective road safety a
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Chameides W., Walker JC. A photochemical theory of tropospheric ozone. Journal of Geophysi-
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(1991) 1954-1962.
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Tomasz E. Burghardt, Anton Pashkevich, Lidia Żakowska
18
Wkład rozpuszczalników z farb drogowych
do tworzenia się ozonu troposferycznego
Tomasz E. Burghardt1, Anton Pashkevich2, Lidia Żakowska2
1 M. Swarovski GmbH, Industriestrasse 10, 3300 Amstetten, Austria, e-mail to-
masz.burghardt@swarco.com
2 Krakow University of Technology, Warszawska 24, 31-155 Krakow,
e-mail apashkevich@pk.edu.pl, lzakowsk@pk.edu.pl
Streszczenie: Rozpuszczalnikowe farby do poziomego znakowania dróg znaczą-
cym źródłem lotnych związków organicznych (Volatile Organic Compounds, VOC). VOC
ulegając rozkładowi pod wpływem promieniowania słonecznego wpływają na powstawanie
w troposferze ozonu, który jest związkiem chemicznym znacząco drażniącym system odde-
chowy i współodpowiedzialnym za powstawanie smogu. Wpływ poszczególnych VOC na
tworzenie ozonu troposferycznego jest nierówny; wartości te zostały określone w maksy-
malnych przyrostowych reaktywnościach (Maximum Incremental Reactivities, MIR). MIR
zostały użyte do obliczenia maksymalnego wpływu rozpuszczalników w farbach używa-
nych w Polsce do znakowania dróg na tworzenie ozonu troposferycznego.
Na podstawie danych z roku 2014, ograniczających się jedynie do dróg zarządzanych
przez Generalną Dyrekcję Dróg Krajowych i Autostrad (GDDKiA), emisja VOC z farb
używanych do znakowania dróg dotyczyła ilości około 494 838 kg, co mogło prowadzić do
produkcji około 1 003 187 kg ozonu.
Jeżeli wykorzystywane byłyby farby bez rozpuszczalników aromatycznych, oparte na
estrach, jak to ma miejsce w Europie Zachodniej, emisje VOC nie uległaby zmianie, ale
potencjał formowania ozonu zostałby ograniczony o 50-70%. Jednakże, z punktu widzenia
ochrony środowiska, najlepszym rozwiązaniem byłoby wykorzystywanie farb wodnych,
wedle wymagań skandynawskich wówczas możliwa byłaby eliminacja do 82% emitowa-
nych VOC i ograniczenie do 95% powstałego ozonu troposferycznego.
Słowa kluczowe: znakowanie dróg, farby wodo-rozpuszczalne, farby rozpuszczalni-
kowe, ozon troposferyczny, VOC, bezpieczeństwo dróg, MIR, ochrona środowiska.
... The presented financial calculation, based on typical retail prices in Poland and assumed higher prices for premium materials, is demonstrating that even very high initial costs are annulled if prolonged service life is achieved. The calculated savings of 0.37 €/m 2 per decade may appear insignificant, but given that approximately 3,436,371 m 2 of road surface was marked in Poland in 2014 at national roads [9], total savings could possibly reach about 125,642.18 € per year. ...
... Modern road marking materials for the use in majority of Europe should be free from heavy metals (like lead) and toxic volatiles (like chlorinated solvents), but the use of toluene is permitted in some countries. The use of toluene as a solvent for road marking paints may be advantageous despite general push toward its elimination, because toluene-based paints may, in some cases, provide better paint adhesion to roadway surface and thus prolong the service life [9]. In addition, in LCA analysis, toluene was judged as better than aliphatic solvents due to required lesser processing [8]. ...
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Introduction On majority of roads, horizontal road markings are essential safety feature that must be periodically renewed to maintain appropriate performance. Results The use of a premium road marking system resulted in prolonged the service life as compared to a standard system, which would be financially-neutral in the long term despite much higher unit and initial costs; advantageously, 54% less glass beads and 63% less paint would be required over 10-year life cycle. When these products usage savings are recalculated into raw materials consumption, the premium system would demand about 21% more of titanium dioxide, but that would be offset by approximately 25% reduction in the consumption of acrylic resin and circa 97% reduction in organic solvents usage and emissions. Conclusions The results from this analysis can be used by road administrators to select the best systems, by policy makers seeking minimisation of environmental impacts, and by contractors who won performance tenders.
... Examples include plasticizers, which increase paint flexibility and prevent cracking, crosslinking agents that improve paint adhesion and durability, and solvents for aid in the dissolution of other ingredients and adjust paint consistency. 14 Retroreflective materials are imperative for nighttime visibility, particularly through the incorporation of glass beads in the paint or pre-applied reflective tapes. 15 The specific combination of these ingredients is tailored to achieve desired properties, accounting for factors such as traffic volume, weather conditions, and budget constraints. ...
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... The observed inadequate adhesion of GB could indicate improper paint formulation, possibly exceeding critical pigment volume concentration (Fatemi et al., 2006). It could not be determined whether the absence of toluene, which was reported as a solvent facilitating adhesion of RM paints to oily or dirty surface through favourable solubility parameters, played any role (Burghardt et al., 2016a). ...
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Road markings are road elements that require frequent periodic renewals (not replacement) to maintain their key properties. To evaluate the impact of materials selection on sustainability of road markings, several representative products were tested in the field. The results revealed that the main impactor for their service life was selection of paint, followed by the choice of glass beads. The measured length of service life was used to calculate the consumption of resources for a series of renewals until end-of-life. The outcome clearly demonstrated that lowest carbon footprint was achieved with road marking materials that afforded longest service life, even if their composition was not environmentally friendly. The methodology described in this article may be used by road administrators and by scientists as a tool for quick assessment of sustainability of road markings based on their service life during homologation testing and composition of the utilised materials.
... RM. Such volatiles can constitute up to 25 % of the paints and some of them can be harmful [16,20]. A field study assessing the exposure of road markers to various solvents was done in Poland: the local OEL (as strict as in Austria) were not exceeded in any of the analysed cases [84]. ...
Article
Road markings, a necessary road safety feature, always contain a layer of glass beads that deliver retroreflectivity for driving at night and simultaneously protect the underlaying paint layer. Even though such glass beads were generally considered as harmless, their analysis for the presence of crystalline silica was not reported so far. To fill the knowledge gap and to confirm the common perception, representative types of glass beads (11 samples from 6 manufacturing plants worldwide) were evaluated for the presence of crystalline phases by X-ray diffraction and their surface was analysed under scanning electron microscope. The study has not indicated the presence of a crystalline phase in amount higher than environmental background and no irregular shard-like surface features were found under microscope. In addition, analysis with inductively coupled plasma – mass spectrometry revealed only marginal content of hazardous elements. The same results were obtained with glass beads manufactured in identical process but used for other industrial applications. This assessment confirmed that the analysed classes of industrial glass beads are fully annealed and amorphous material that is free from hazardous ingredients.
... Solubility parameters that describe the sphere of solubilising a resin by a solvent were first described in the 1960s; 30 such consideration is important because it might affect paint adhesion to the road surface. 31 Amongst the exempts solvents listed in Table 3 one should observe their environmental friendliness, according to characteristics used in solvent selection tools. 32 an unknown reason. ...
Preprint
European Union Green Public Procurement (GPP) criteria for road marking materials (comprising paints, plastic masses, and tapes) have been recently published. Among the criteria, the key is limitation in the contents of Volatile Organic Compounds (VOC); as a novelty in Europe, several solvents would be exempt from the VOC content calculations. Other parameters include exclusion of hazardous materials, heavy metals, and ingredients that would cause significant hazard warnings. In addition, contents of titanium dioxide and the quantity of recycled materials in glass beads are specified and durability of road marking systems is included. In this review, the key points of the GPP are assessed and uncertainties are pinpointed and discussed. Particular attention is given to solvents, which belong to inalienable ingredients in road marking paints. Amongst demonstrated weaknesses of the GPP, the use of nominal VOC contents instead of Ozone Formation Potential and downplaying the impact of service life on overall emissions and materials consumption appear to be the most important. Results from field testing of road marking paints are provided to exemplify this weakness.
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This paper reviews the research progress and development of aluminate long afterglow luminescent materials in the field of road marking, especially the study of rare earth ion-activated strontium aluminate (SrAl2O4: Eu2+, Dy3+)-based long afterglow powders. This article begins by describing the importance of road markings and the need to improve their visibility and durability at night and in adverse weather conditions. Subsequently, the current passive and active methods for improving the visibility of marking materials are discussed in detail, focusing on the advantages of aluminate long afterglow materials and challenges related to their hydrolysis and thermal stability. Through the application of organic–inorganic composite coating technology, the water resistance and thermal stability of the materials can be improved, thus enhancing the performance of road markings. This article also summarizes the current research status of different types of long afterglow road marking coatings. It analyzes the luminescence mechanism of aluminate long afterglow materials. Additionally, this article discusses future research directions and application prospects. The aim is to provide technical references and support for the wide application of long afterglow self-luminous road marking coatings.
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Road marking is a core part of traffic safety facilities that plays an irreplaceable role in traffic control. With the increasing requirement for road marking, active luminous road markings (ALRMs) have been proposed and have progressed over the years owing to their compelling features of autoluminescence and good recognition. However, there are still some limitations to be further studied, including the luminescence performance, long-term durability, and economic cost. In this study, a comprehensive analysis was conducted to understand the state-of-the-art progress and required future work on ALRMs. Different types of ALRMs were classified, including fluorescent road markings (FRMs), persistent phosphorescent road markings (PPRMs), and electric luminous road markings (ELRMs). Moreover, this paper elaborates on the technical principle, service performance, applications, and existing problems associated with various ALRMs technologies in detail. Furthermore, the challenges and future prospects involved in the development of ALRMs are emphasized to provide avenues and opportunities for future research. It is anticipated that PPRMs and ELRMs, as next-generation road markings, will exhibit the unique advantages of traffic safety improvement, smart traffic control, and an intelligent transportation system.
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As a necessary component of traffic signal and the safety features on traffic system, pavement markings could not be replaced by other means currently. With the enhancement of environmental and healthy requirements, it was also crucial to reduce energy consumption and negative environmental impact of marking materials. This review synthesized the state-of-the-art technologies and applications of marking materials in pavement engineering in terms of environmental impact and cost evaluation. Firstly, the common raw materials of pavement markings were introduced, including glass beads, binder, pigment, filler and dispersion medium. Afterwards, this article comprehensively classified marking materials, involved thermoplastic markings, paint materials, cold-plastic markings, two component markings and marking tapes. Especially, the application of waterborne paints was highlighted, which had presented potential advantage on environmental protection, cost saving and heath issue. In addition, the performance requirements of marking materials were discussed, focusing on the retro-reflectivity and durability. For the uniformity of traffic marking system, the necessary of developing specifications and pavement marking management system were emphasized. Subsequently, life cycle assessment analysis on pavement marking materials was considered based on the cost and environmental impacts, typically involved the volatile organic compounds, heavy metal and glass beads. Finally, advanced marking materials and innovative applications were described and investigated, including photo-luminescent coating, nanocomposite paints and translucent concrete-based smart lane separator. Moreover, prospects and conclusions were summarized to present the avenues and opportunities for future researches. The pavement marking industry would continue to concentrate on safety, performance and environment aspects while taking the advantage of the technological advancements in future.
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Horizontal road markings are very important safety features on almost all roads. For proper function, they must be reflectorised with glass beads, which provide visibility in the night time and simultaneously protect the paint from abrasion. Nonetheless, to maintain adequate performance frequent renewals are required. Field tests have demonstrated that durability achieved with modern waterborne road marking paints can be higher than measured with solventborne materials and that further improvements in durability of all paints can be achieved with the use of premium glass beads. Given that all paints dry because of evaporation of solvents to the atmosphere, emissions of Volatile Organic Compounds (VOC) reach approximately 25% for solventborne paints and below 5% for waterborne paints. The emitted VOC contribute to formation of ground-level ozone unequally, so Ozone Formation Potential (OFP) is used for a uniform comparison of various paints. For example, in Italy an annual reduction in OFP from 3,498 to only 43 tonnes could be realised by using highest quality waterborne road marking paints reflectorised with premium glass beads, due to the combined effects of lower individual OFP and improved durability. These results should be considered by road administrators and environmental agencies seeking a method to simultaneously improve air quality and decrease the frequency of renewals.
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Ground-level ozone, worldwide recognised amongst key pollutants responsible for smog and a significant pulmonary irritant is formed in troposphere via a photolytic process from nitrogen oxides (NOx). Volatile Organic Compounds (VOC) during their decomposition in the atmosphere interact with NOx and thus affect ozone formation. Their interactions are not equal and have been quantified in Maximum Incremental Reactivities (MIR). Using MIR, calculated was ozone formation potential of VOCs emitted from an aromatic solvent-containing paint that is used for marking of roads in Kraków, Poland. To simulate possible environmental benefits of using alternative materials, analysis was then extended to model paint without aromatic solvent and a waterborne paint.
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Horizontal road markings are one of the essential safety features of modern roadways. All of the utilised systems consist of a pigmented coating containing partially embedded retroreflective elements such as glass beads. In addition to durability and functionality of the road marking, ease of application and effect on human health and environment are primary considerations for their selection. Road marking systems can be divided into plural component materials that cure due to chemical reaction occurring at the site of application, thermoplastics that require heat for application, and paints, drying upon evaporation of the dissolving medium. The focus of this paper is on road marking paints with a special emphasis on contemporary waterborne materials. Over 100 years old solventborne technology furnishes paints that afford consistent application properties under a variety of conditions such as lower temperatures and high humidity. Their environmental and human health impact is significant and durability quite poor. Modern waterborne paints are based on acrylic resins and incorporate developed in the 1990s quick-set chemical mechanism for drying. Under favourable weather conditions, they dry faster as compared to solventborne. However, their known weakness is risk of washout in case of rain and sluggish development of washout resistance at marginal application conditions like high humidity and low temperature. Impact of waterborne paints on human health and environment is very significantly minimised as compared to other materials. Their durability is significantly higher as compared to solvent-based paints. Analysis of characteristics of waterborne road marking paints and preliminary results from their trial application in Croatia are presented herein. Based on the presented comparison with solventborne materials, after results from test application become available, intelligent decisions regarding future use of waterborne road marking paints in Croatia and other countries that have not embraced this technology shall be possible.
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The main objective of this study was to determine if a minimal increase in road light level (luminance) could lead to improved driving performance among older adults. Older, middle- aged and younger adults were tested in a driving simulator following vision and cognitive screening. Comparisons were made for the performance of simulated night driving under two road light conditions (0.6 and 2.5 cd/m 2 ). At each light level, the effects of self reported night driving avoidance were examined along with the vision/cognitive performance. It was found that increasing road light level from 0.6 cd/m 2 to 2.5 cd/m 2 resulted in improved recognition of signage on straight highway segments. The improvement depends on different driver-related factors such as vision and cognitive abilities, and confidence. On curved road sections, the results showed that driver's performance worsened. It is concluded that while increasing road lighting may be helpful to older adults especially for sign recognition, it may also result in increased driving confidence and thus reduced attention in some driving situations.
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The retro-reflection of light by glass beads injected in road stripes is studied experimentally and theoretically. The complete contribution of the retro-reflected intensity is modelled by taking into account the glass beads and the paint stripes. The efficiency of such a technique is evaluated for various compositions and densities of glass beads injected in paints, including the paint meniscus contributions.
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In order to get a better insight into the safety effects of alternative road designs, the subjective safety experiment has been conducted. The experiment has been designed to test the effect of geometric design characteristics and road environment on the subjective safety of rural road curves. The method used here allows to investigate the effect of a real driving environment on safety in a complex way. The results have shown the importance of the composed effect of curve geometry and curve environment on the subjective safety of rural curves.