1) The document discusses the importance of skid resistance for road safety and describes how it depends on macrotexture and microtexture. 2) It explains that microtexture durability is influenced by aggregate resistance to polishing, which is measured by the Polished Stone Value (PSV). Higher PSV indicates better skid resistance. 3) The document presents test results showing that mixing high PSV aggregates with those of lower PSV can meet performance needs while being economically competitive. This allows for a wider range of aggregate sources.

1. Asphalt concrete HA
Let’s keep your grip!
The last one varies according to the geologic nature
of the operated deposits, to the mineralogical
composition and to the size of the minerals forming
the rock.
As the safety of the road has become a major
The durability of the microtexture depends especially
concern in our society, the needs in skid resistance
on the resistance to polishing of the aggregates,
have increased, especially on the exposed itineraries
measured in the laboratory by the accelerated
(high speed, blends, braking…).
polishing coefficient called PSV (Polished Stone
The skid resistance of a surface layer corresponds
Value) according to the standard NF EN 1097-8. In
to its capacity to mobilize friction forces between
the pneumatic and the road to allow acceleration,
vehicle’s guidance and braking.
It depends on two characteristics:
> the macrotexture of the surface layer (irregularities
of the surface between 0.5 and 50mm),
> the microtexture of the chippings (irregularities of
the surface smaller than 0.5mm).
the first approach, one supposes that the higher the
PSV value is, the more material is "skid resistant".
This durability can also be evaluated by the Wehner
and Schulze test that allows to express the evolution
of the skid resistance coefficient of materials or of an
asphalt concrete in terms of traffic.

2. k
ey figures
Results of Wehner and Schulze test between
an aggregate and two mixtures of aggregates
PSV value
higher than 56
More than
1.5 million tons
of aggregates with high PSV
produced by Eurovia every year
v
aried aggregates
Eurovia, European leader in the production of
aggregates, has a network of more than 400
quarries worldwide elaborating every year about
100 million tons of aggregates.
In order to satisfy the requirements of the projects
and the standards regarding PSV (NF EN 13043),
Eurovia produces materials for surface layers with
PSV values between 50 and 64.
0.5
0.4
0.3
0.2
Rugovia® TM 50% PSV = 52 + 50% PSV = 60
Rugovia® TM 80% PSV = 52 + 20% PSV = 60
Rugovia® TM 100% PSV = 52
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
The asphalt concretes for surface layers that
have an exceptional skid resistance are now
characterized by Eurovia with the letters HA.
This concerns surface courses produced with
aggregates or with a mix of aggregates with a PSV
higher than 56. For example the very thin Microvia®
TM, gap graded bituminous micro concrete 0/6,
designed with aggregates the average PSV of which
is higher than 56, becomes a Microvia® TM HA.
c
onclusive tests
However, sometimes quarries located near the
jobsites do not show the PSV conditions required
in some bids. In the contrary, some high quality
deposits are too far away to be economically
competitive. By mixing high PSV aggregates with
good quality materials but with lower PSV, it is quite
possible to meet the needs of the client.
When laying different VTLAC on highways with high
traffic the surface characteristics at early stage
have been compared.
There are several advantages:
Proposing a performing technical solution at
competitive price,
Offering a new perspective to quarries far from
activity centers,
Average SFC
PSV
(NF EN 1097-8) (NF P 98-220-3 and 4)
VTLAC
51
0.64
VTLAC HA no. 1
58
0.68
VTLAC HA no. 2
51 (80%)
58 (20%)
0.67
Rugovia® et Microvia® are registered trademarks.
Saving high potential resources.
TECHNICAL DEPARTMENT
18, place de l’Europe - 92565 Rueil-Malmaison cedex
Tel.: +33 1 47 16 38 00 - Fax: +33 1 47 16 38 01
www.eurovia.com
technique@eurovia.com
- October 2013 - 500 copies – Photos: Eurovia photo library
t
he winning mixture