Construction World June 2017

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CONSTRUCTION WORLD JUNE 2017 34
ROADS AND BRIDGES
Reinforced Earth® structures behave
as a coherent gravity mass comprising a
selected granular fill combined with strong
steel or geosynthetic reinforcing strips and a
modular facing system, generally in the form
of precast concrete panels, welded wire
mesh or semi-elliptical steel panels.
This unique combination creates a dur-
able mass gravity structure which in addi-
tion to carrying its own weight, is capable of
withstanding significant static and dynamic
loads generated by all stresses external to
the structure.
The Terre Armee Group
The invention using earth as a raw
ingredient, led within a few decades, to
the development of a company with a
presence in five continents. Easy to install,
Reinforced Earth® rapidly established
itself as an ideal construction material in
numerous applications, in particular road
systems. Vidal founded the company Terre
Armee Internationale, and so the story of
an invention turned into one of legendary
entrepreneurship.
Reinforced Earth or RESA is the name
of the TAI South African company estab-
lished in 1975 to provide a Reinforced Earth®
service in sub-Saharan and Eastern Africa
and in Ghana and Nigeria.
Trademarks
Reinforced Earth® is a trademark belonging
to Terre Armee Internationale. It is registered
in numerous African countries including
South Africa.
Wikipedia defines Mechanically
Stabilised Earth as follows: “Mechanically
stabilised earth or MSE is soil constructed
with artificial reinforcing. It can be used for
retaining walls, bridge abutments, seawalls
and dikes. Although the basic principles of
MSE have been used throughout history,
MSE was developed in its current form in the
1960s. The reinforcing used can vary, but
include steel and geosynthetics. MSE is the
term usually used in the USA (and Africa)
to distinguish it from the name ‘Reinforced
Earth, a trade name of the Reinforced Earth
Company, but elsewhere Reinforced Soil is
the generally accepted term”.
Reinforced Earth® today
The TAI Group
The group has 50 companies worldwide
and has contributed to more than 50 million
square metres of structure face area in
over 100 countries. The companies are
Reinforced Earth® is the English name given to the material Terre
Armee ® which Frenchman Henri Vidal invented in 1963.
A SIMPLE, YET COMPLEX MATERIAL
“It all began one fine September day on
a white sandy beach. I put some pine
needles into a heap of sand and noted
a certain cohesion. I had in fact created
the first Reinforced Earth®.
“Structure made up of two
components: granular particles and
reinforcing strips. Man’s first building
material comprised just one component,
granular particles in the form of stones.
And then concrete, so two components:
granular particles and a bonding agent,
in this case cement. Then man invented
reinforced concrete made up of three
components: granular particles, a
bonding agent and reinforcing bars. In
simple terms, Reinforced Earth® involves
eliminating the bonding agent and
keeping only the granular materials and
reinforcement. But it wasn’t easy.
“It took me five years to establish
the theory based on friction between
particles and reinforcing strips and
to design a technology that was both
economical and quick to install. Then
I filed patents and realised that there
was nothing else like this in the world.
I began building the first structures
and started developing an international
organisation to allow the structures
to be installed rapidly across all
continents.” – Henri Vidal
THE INVENTION
staffed with local employees driven by a
shared passion that is a central element of
the corporate culture and unites the teams
across all geographic borders. RESA has
contributed significantly to road, rail and
bridgework in Africa. Hundreds of contracts
have been completed. Four major contracts
are listed:
• N1 Diepkloof, Johannesburg 1980 –
one of the first true bridge abutments in
Africa. Since then some 200 such
abutments have been completed or are
under construction.
• N1 Du Toitskloof, Western Cape 1994 –
numerous retaining walls constructed
on a new dual carriageway alongside the
Molenaars River.
• Mbabane Bypass, Swaziland 2004 – 24
true bridge abutments 15 retaining walls
and four tiered fills. The most notable and
spectacular, are the tiered fill structures
which were designed as alternatives to
incrementally launched bridges.
• Gautrain, Gauteng 2008 – 80 structures
were constructed on 38 separate
sites including true rail over road
bridge abutments.
Reinforced Earth®, Terratrel™ and Terraclass® – our three solutions improve The N7.
John Vorster offramp to Viaduct 5.