1. Temperature management by heat energy absorption with Glass Ceramic mineral in HMA
By: Ing. P.A. Landa, management director Asfalt Kennis Centrum (Asphalt Knowledge
Center, AKC)
Introduction:
Asphalt is a thermo plastic material which is a result of the visco elastic properties of the
bituminous binder.
It enables the material to have flexible performance under slow setting conditions and a stiff
response on fast moving traffic loads. It is absorbing the stress which is created in the material
by this heavy traffic. However, with slow speed rates this can creates the issue of rutting by
the plastic behavior of the material under high temperature conditions in summertime.
Even without the load of traffic the asphalt pavement suffers due to the climatic conditions,
especially in continental and desert climates with extreme high and low temperature changes
during day and night.
Obscurea Road, ‘the material’ is an innovative patented polycrystalline mineral thixotropic
product solution designed to substantially widen the temperature window for safe
performance under extreme climatic conditions and strengthening the asphalt by absorbing
damaging heat energy created by Infra-Red and Ultra Violet as well as any other heat energy.
This performance is gained as a result of phase changes within the material itself which is not
visible to the naked eye. The material manages this as it acts as the hosting material
“protecting” against a fast, high and fluctuating rate for temperature increase or decrease.
The material was tested as a filler in an HMA dense asphalt top layer which is used across the
world for asphalt roads/pavements in urban areas, highways and Industrial sites. (AC 11 Surf)
The material was tested by AKC under the Standard conditions for the determination of the
functional properties regarding the European Normalisation standards for CE marking.
This is done at normal moderate European temperatures between 15 and 50°C.
To demonstrate the performance under extreme climatic conditions by exposure to extreme
high and low temperatures created by Infra-Red and UV and a freeze thaw test the
temperature profile is compared with the same asphalt material without the additive.

2. Testing protocols for the functional properties for CE marking:
The materials were mixed pursuant to EN 12697-35 and plates and cylindrical gyrator
specimen were prepared pursuant to EN 12697-33 and 31.
After preparation of the beams the material was tested to determine Stiffness and Fatigue
pursuant to EN 12697-26 and 24 at 20°C
The resistance against permanent deformation (rutting) was tested pursuant to EN 12697-25 at
50°C.
The water-sensitivity was tested pursuant to EN 12697-12 and 23 with 40°C conditioning in
water and 15°C testing temperature.
Results of the EN standarised testing methods for the Functional Properties
The results are summarized in the next table:
Results units conditions Obscurea Road
mix AC 11
Surf
AC11 Surf
reference
window
Air Voids % 20°C 3.9 2-6
Water
sensitivity
% 40 - 15°C 90 82-98
Tensile
strength
MPa 15°C 3.16
Rutting Fc max 50°C 0.35 0.1 -0.7
Stiffness MPa 8 Hz, 20°C 6040 4500 – 6600
Fatigue ɛ6 µm/m 30 Hz, 20°C 107 102 - 120
Ranking with the Dutch specifications:
The results are according to the Dutch specifications for the performance class DL-C and
capable for a High Way application with > 2500 heavy trucks per day and a total load for >
1.37
ESAL 100 KN during the theoretical designed service life of 12 years.
Based on these specifications a CE mark was released for this mixture with the material
additive.
The material can be safely used for this application and will be able to protect asphalt
roads/pavements against extremer temperatures then “covered” in these tests.
To demonstrate the effects at higher and lower temperatures the material was exposed to a
wider temperature window between -20 and 75°C.

3. Testing of the material under more extreme climatic conditions:
Asphalt is exposed to relatively high and low temperature environment which in extreme
cases may vary between -50 and + 70 ° C. The frequency at which this happens negatively
affects the structural surface continuity of the asphalt. This results being shrinkage and
deformation tension cracks. If these stresses can be reduced by absorbing and delayed
releasing these thermodynamic energies, then the asphalt will be less negative addressed the
climate will be improved durability.
The European standards and specifications are suitable for the average climatic conditions in
Europe. The tests are executed between 15 and 50°C. However, the extremer high
temperatures in the Mediterranean climate and lower temperatures in the Nordic climates are
not fully “covered” in these testing protocols. A window of -20 to + 70°C for pavement
temperatures are necessary to cover the extreme temperatures in these climates.
The material was tested in climate chambers with frost/thaw conditions for the low
temperatures and even submerging the material in liquid Nitrogen of -196 °C.
For the high temperatures the material was exposed to Infra-Red and UV light where the
material temperature was raised to 75°C.
Specimen with and without the Obscurea Road additive were monitored for the temperature
management on the surface and in the centre of the bulk material.
High temperatures:
The specimen with the material were first submerged in an adiabatic bath up to 75°C at
different stages and over differing periods of time. There was no significant difference in
temperature profiles. This type of energy transfer is realised by heat conduction. See picture 1.
This form of energy transfer was simulated to create the condition of air temperatures above
40°C as an asphalt road/pavement can be easily heated up to more than 70°C as a result of
direct sunshine with IR and UV radiation as energy “transporters”. To simulate these effects,
the energy was transferred in the form of radiation by electrical radiators and bulbs.

4. It was observed that the specimen with the material recorded a difference of being 4°C cooler
at a level of 75°C, over the standard sample. See picture 2.
The specimens were exposed to heat radiation in two different ways:
 UV radiation (2 weeks at 300-400 nm with 45 W/m2)
 IR Radiation (2000 W, distance 0,35 m)
Temperature probes were placed at the surface and in the centre of the cylindrical specimen.
Picture 1: Energy transfer by Heat Conduction

5. Picture 2: Energy transfer by Heat Radiation (IR)
Low temperatures:
The specimens were tested in a Freeze Thaw climate chamber and also in this case there was
only a slight difference in temperature. The material with the Obscurea Road additive stayed
max. 1°C higher in temperature at a level of -20°C. See Picture 3.
Another test was done with submerging the material in Liquid Nitrogen and the data is not yet
available for reporting the results. See Picture 4.
Both tests are also systems with an energy transfer by Heat Conduction.
Ideas about Cooling down tests by “Cold” radiation are under construction.
A freezing night with an open sky and no wind shear will result in very low material
temperatures when they are exposed to the sky and can release the heat energy in the material
by radiation. In desert climates this is very often the case where exposure to the sun during
daytime and cooler nights creates high stresses into asphalt roads/pavements.

6. Picture 3: Freeze Thaw test (-20°C / +20°C)
Picture 4: Submersion in Liquid Nitrogen (-196°C)

7. Obscurea Road™ Solution for The Ageing Properties of Bitumen and Asphalt:
The result of an ageing bitumen binder is a brittle binder with increased stiffness and reduced
flexibility. It has a similar effect as a harder binder which is not suitable for that particular
climate. The low temperature properties of an aged binder will be affected and the tensile
stresses will be building up when the material is aged over the thermal cycle, it becomes more
brittle and as a result of that shrinkage cracks occur in the asphalt pavement which leads to
rutting.
This Ageing process is influenced by temperature and the UV radiation spectrum of sunlight.
The UV radiation works as a catalyst on the binder in the top layer, which expedites
deterioration as a result.
The lighter fractions in the bitumen will oxidise and will become more reactive and change into
larger molecules. In the end the balance in the typical SARA bitumen components (Saturated,
Aromatics, Resins and Asphaltenes) is lost and the material becomes a more brittle behaviour.
Aged material like RAP (Recycled Asphalt Pavement) can be “repaired” by using softer
bitumen to make a blend of the right properties. A high quantity of softer bitumen (one or two
grades) are need to have the needed effect. There is always a discussion amongst scientists or
this is really happening or that a 2-layer system will be created with no homogeneity and still a
worse performance which belongs to hard and soft binders. The next figure is showing the two
cases between ‘Black Rock with a soft Skin’ and a rejuvenated binder blend with good
homogeneity.
Special additives from the Chemical Industry for improvement of the ageing susceptibility by
additives are common sense for plastics made of crude oil. Special cut backs which are chemical
modified are often used as a “weak maker”, however these materials are often prohibited for
Health and Safety reasons.
The material by encompasses resistance to the climate in particular water and air results in
substantially slowing the ageing effect of Sunlight by further absorbing the 94% UV radiation
and 96% Infrared radiation thereby reducing the chemical catalytic oxidation process of the
asphalt road/pavement.
The material tested being a suspension of special polycrystalline minerals in a natural bio-based
resin as an additive for bitumen and Asphalt is environmentally and human friendly. [1]

8. Obscurea Road™ Solution For Extreme Climates:
Hard binders are very often used for high performance asphalt mixtures like EME in France.
However, the application in colder climates can give temperature cracking problems in the
winter. In the application phase the Hard Binder product needs also a higher production
temperature and this costs more energy with a higher CO2 emission. The higher production and
application temperatures are also initiating a higher risk for early ageing. (ageing is temperature
dependant) The Bio Based Resin additive in the material improves the workability of the mix
and enables normal production and application temperatures. As a result, the ageing is less and
also the low winter temperature properties are greatly improved.
It has been observed that the material substantially extends and improves the temperature
window simultaneously for both the extremes of low in winter and high in summer.

9. Conclusion:
The Asphalt Knowledge Centre (AKC) did a research program in the application of Obscurea
Road TM
in a standard AC 11 HMA top layer. [4]
Obscurea Road™ is a thixotropic product which readily blends with all bitumen grades.
It was found that the material by scavenging the UV radiation and absorbing the IR radiation
provides protection against the damaging effects of UV and IR radiation to the bitumen. As the
expected result will age the bitumen will age more slowly, staying cooler when subjected to hot
climatic conditions and warmer when subjected to cooler climatic conditions. The benefit of
slowed ageing in the asphalt road/pavement provides more flexibility of the minerals, delayed
brittleness resulting in substantially reduced temperature stress which substantially decreases
rutting and cracking in turn provides a longer service life.
It was found that the material substantially expands the operating range of an asphalt road/
pavement reducing the effects of the thermal cycle.
It was found that the damaging effects of thermal fluctuations which age the bituminous asphalt
are substantially reduced by the material which absorbs 96% of the infrared spectrum and 94%
of the Ultraviolet spectrum without damaging the bitumen. [1]
The material by attaching to the polymer chain of the bitumen stabilizes the thermal fluctuations
by 17.5%. This enables the use of harder grades of bitumen, normally not suitable due to their
susceptibility to thermal fluctuations, which are stronger. This results in substantial reductions
in rutting caused by the thermal cycle.
It was found that when the material was blended into a standard Asphalt formula, then compared
to a further standard Asphalt sample without the modification to the Bitumen. Both were
subjected to the full range of Ultra Violet at 20°C. The Asphalt modified with the material, was
found to have a 17%, 3.4°C, cooler surface. By reducing the temperature in hot climatic
conditions you reduce the rutting on an Asphalt surface. By way of example of the effect of
reducing the temperature of the surface, part of the Dutch Road Network was covered with
‘Porous Asphalt’ which lead to a 2°C decrease in the temperature this resulted in reduced rutting

10. and extended service life compared to the previous Asphalt AC 16 top layer mix under similar
conditions. [3]
It was found that the material increases the strength of the Asphalt by 35% when compared to
an Asphalt mix without the material. This increased strength results in higher bearing capacity
and longer service life of the construction. [4]
The dense AC top layer when modified with the material was found to meet the specifications
for high way application in the Netherlands and is suitable for a traffic load of 2500 heavy
trucks per day which is equal to 17.5 million ESAL100KN[4]
Reference:
[1] Description of the principle of proof of the Obscurea Road™ material
[2] Internal AKC report about the UV and Infra-Red heat transfer into samples with and without
Obscurea Road™ Material.
[3] CROW publication “Stiller verkeer.nl”
[4] AKC Type Test report AC 11 surf with Obscurea Road™