A world first for the Villa Navarra by Rudy Ricciotti - Lafarge

A world first
for the Villa Navarra
by Rudy Ricciotti
A 40m-long Ductal® roof
with a 7.80m cantilever
Press kit
May 2008

In the town of Le Muy, located in the Var département in the south of France, architect
Rudy Ricciotti recently completed a villa and art gallery for art collector and dealer,
Enrico Navarra.
Nestled in the sloping hills to blend in with the surrounding Provencal landscape and
reduce the building's impact on the site, the Villa Navarra is characterized by its roof
made out of Ductal®, the ultra-high performance concrete developed by Lafarge. The
structure is like an immense visor, 40m long, with a 7.80m cantilever, 3cm thick at its
tip.
AN UNUSUAL ORDER, REQUIRING INNOVATION AND EXPERTISE
The Villa Navarra was born of Enrico Navarra's desire for a building half way between a
house and an art gallery. The art collector and dealer decided to call on architect Rudy
Ricciotti, inviting him to undertake a unique creative process.
“The intention is for the villa to be an art gallery which can be visited by internet”,
summarizes Rudy Ricciotti, “and it will not be open to the public. It’s an abstract place, whose
function is to constitute an enigma.”
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A DISTINCTIVE ROOF STRUCTURE
Hidden away in the hinterland of the Var coastline, the building achieves its objective by
nestling into the Provencal landscape. The desire for discretion is driven by the
environmental concern to limit the impact the building has on the overall site. This discretion
dictates the positioning and the form of the construction, which has a modest profile. The
platform was cleared prior to construction, leaving the rock bare and the plot of land stripped,
to be planted in the future with cork oaks and cypresses. There is a direct relationship with
the landscape. Hugging the contours of the land, the building has a shape that recalls that of
the old dry stone walls so characteristic of the region.
The Villa Navarra is a simple rectangle 40m long and 10m wide, built on one level and
doubled by a pond which stretches out into the surrounding landscape. It features a
characteristic roof in Ductal®, the ultra high performance concrete by Lafarge: an immense
visor stretching 40m long between the trees. The 7.80m cantilever opens up the house to the
wild Var landscape. Only a thin line of façade gives away its modest presence.
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A UNIQUE MATERIAL FOR A SINGULAR PROJECT
By concentrating on the roof, the project took on a structural challenge, going beyond the
original specifications to become a work of art. The project became a kind of prototype, and
its execution a real case study.
“The roof was the opportunity for all of us to think about a structure working mainly through
flexing, due to the cantilever which typifies it and with no pre-stressing, the engineer’s normal
approach, in order to thoroughly test the qualities of the material”, explains Mouloud Behloul,
the engineer in charge of Ductal ® at Lafarge. The 7.80m cantilever makes the roof one of a
kind and its execution in Ductal ® is a world first.
A DESIGN WHICH ALLOWS THE MATERIAL TO EXPRESS ITS UNIQUE QUALITIES
Made up of 17 juxtaposed panels, the roof of the Villa Navarra makes full use of Ductal ® ‘s
qualities. As a specialist in mathematic modeling and a civil engineer, Romain Riccotti came
up with the shape and dimensions through painstaking drafting, taking into account the
following factors: transport issues, the weight of each panel, the changes due to weather
conditions, wind resistance and the heat expansion it is likely to suffer from in a region with
extremes in sunshine and winds. These extremes are emphasized as the surface of the uninsulated
roof is left bare, in order to make the most of the finished look and the waterproof
qualities of the Ductal ® panels.
"The choice of Ductal ® was not made by
chance, no more so than for the cantilever. They
help the building to blend into the surrounding
oak forest. This is achieved through the two
surfaces (the pool and the glass surface) which
reflect the landscape over a distance of 40m, as
well as the limited visual impact owing to its
reduced thickness. The pre-casting and finesse
of Ductal ® solved a range of architectural and
technical problems: the lack of steel and
therefore coating, the reduced thickness,
transport and handling, integrated and monolithic primary and secondary structures,
distribution of stress, watertightness, and so on," explains Romain Riccotti.
Each panel is 9.25m by 2.35m, and is made of a plate of a regular thickness edged by two
lateral progressive inertia ribs, higher where the supports are located and gradually
becoming thinner, meeting the thickness of the plate at its tip. The ends have a clever open
design to save weight and to allow the light to enter this part opened up as a porch.
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“The design produces an optimal mechanical result, which is not without similarities to steel
structures, comprising a web, wings or a purlin,” comments Romain Ricciotti, “and this form is
not the result of any particular design specification.” "The material as it is used in the project
gives a stunning performance of its qualities," adds Rudy Ricciotti.
PRECASTING - THE ART OF MOULDS AND POURING
The production of the mould and the method of pouring are determining factors for the
production of these parts with elaborate and complex shapes. The company Bonna Sabla,
located near Montpellier, was selected for its expertise to carry out the precasting of all the
Ductal ® components. The metal moulds were manufactured by a supplier from the
aeronautical industry.
In-depth study of the flow of liquids was carried out to optimize the direction of the metal fiber
used in Ductal ® . As the mechanical performance is dependent on the direction of the fibers,
the pouring process must be determined to align the needles in the direction of the flow of
liquid. The extremely fine texture of Ductal ® , whose largest particles are no bigger than 0.5
mm, facilitates this hydraulic behavior, which conditions the mechanical direction of the
needles carried by the flow.
For the production of the Villa Navarra panels, the moulds were set up back to front, pouring
was carried out longitudinally for the profiled ribs on the edges and transversally for the plate.
The mould is turned out after steaming at 90° for a more rapid curing of the concrete. It gives
a smooth and shiny surface, of which the burnishing is accentuated by the darker tones
caused by the fines used in the formulation of the concrete.
"The most complicated thing was to combine high performance technology, from the
aeronautical techniques used in the steel moulds, with precise pouring methods to guide the
metal fibers according to the desired structure, while retaining the skills and art of
craftsmanship," Rudy Ricciotti points out.
4

THE ASSEMBLY STAGE - A STORY OF FELLOWSHIP
In addition to the opinions of experts in the field, in particular Jacques Resplendino (the Setra
engineer who compiled the standard for UHPFCs), the assembly required a methodological
approach involving the stonemason Ortunio. Putting the 3-tonne panels in place and
transporting them by truck to the sloped site called on the expertise of all involved.
The panels were lifted by a field crane and
positioned on the two supporting beams,
then pushed against the preceding one by
being slid sideways and finally propped.
They were joined by mortise and tenon at
the bulge in the ribs by the positioning of a
socket subsequently injected with resin.
Supporting braces, made up of a rod
inserted in a socket injected with resin and
bolted at the surface with a wing nut
holding in place a load spreading plate,
were placed along the back beam. For the
second beam, simple neoprene cushions form the support.
In order to avoid any tapping in the façade between these juxtaposed panels, similar to giant
tiles placed edge to edge, a system of transversal axes in the form of a steel rod anchored in
the lifting points at the ends of the panels and sealed by a resin, reinforces them. A silicon
joint is then put in place, ensuring that the upper part of the ribs remain waterproof, which are
then joined and reinforced.
“Mutual trust was created from one end to the other of the chain, making the operation a
story of fellowship,” concludes Rudy Ricciotti.
5

DUCTAL ® , AN EXCEPTIONAL ARCHITECTURAL MATERIAL
Developed by Lafarge, Ductal ® ultra high performance fiber reinforced concrete has
innovative properties which pave the way for architectural designs hitherto unheard of. Its
special composition gives it exceptional compressive strength, six to eight times greater than
normal concrete. For structural applications, the use of special metal fibers provides Ductal ®
with ductile properties, hence the name: with flexural strength ten times that of standard
concrete, it can undergo substantial working stress without shearing.
Ductal ® is easy to use, and provides an infinite number of new possibilities. Its fluidity and the
absence of conventional aggregates in its composition enable it to adapt to the slightest
detail in the formwork and allow for the creation of extremely fine and thin forms that cannot
be obtained with a traditional concrete structure. The resulting surfaces reproduce the texture
of the moulds with exceptional precision. The surface appearance can thus adopt a range of
aspects, and when polished, it can even imitate stone or marble, providing a remarkable
esthetic finish. Ductal ® is resistant to corrosion, abrasion, pollution, bad weather or shocks,
giving it a life span 2 to 3 times longer than that of conventional concrete.
Ductal ® forms an integral part of a sustainable development approach. Its mechanical
performance, combined with its durability, its esthetic qualities and its high compactness help
reduce the environmental impact of construction, throughout the building's life cycle. Ductal ®
requires half as much raw material and energy and results in CO2 emissions of up to half
those induced by conventional concrete. It features the thermal mass capacity of concrete
which, when optimized, helps reduce energy expenses when the building is in service. All
these features make Ductal ® a high performance and durable construction material to create
the most impressive feats in architecture.
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INNOVATION AT LAFARGE: INVENTING TO BUILD A BETTER TOMORROW
Over 500 people worldwide work for Lafarge in Research & Development, working to
improve products constantly, proposing new solutions which generate value for the entire
building profession and which can help to reduce the environmental imprint of buildings.
The Group boasts the world's leading building materials research facility with the Lafarge
Laboratoire Central de Recherche (LCR) at Isle d’Abeau in France, which houses 6,000m2 of
laboratory space equipped with highly sophisticated testing and analysis instruments. This
research facility was set up in 1990 and now employs over 200 researchers of about ten
different nationalities, working to understand basic mechanisms and validate technological
breakthroughs.
The techniques and instruments developed over the last twenty years have made it possible
to develop a scientific approach to cement and concrete. Today, it is possible to analyze
these materials at the nanometric level, revealing the high technicity of concrete in many
respects (physical and chemical phenomena, sensitivity to external parameters, change in
mechanisms over time, etc.).
The scientists at Lafarge have thus been able to identify and better understand the different
phenomena underlying the behaviour of concrete, knowledge that led to the development of
Ductal®, an ultra-high performance concrete, more ductile, more durable, stronger than
traditional concrete and Agilia®, a range of self-compacting concrete products, which
considerably improve esthetical appearance and on-site implementation. These materials
enable Lafarge to handle the increasingly complex demands made by architects, design
offices, contractors and builders, while working with the other players in the sector to rethink
building systems and to design buildings which consume less energy, and therefore have a
more limited ecological imprint.
The Group worked in partnership with architect Jacques
Ferrier on "Hypergreen", a concept of a tall building
respectful of the environment, presented at the MIPIM
in 2006.
7

RATP bus center in Thiais, near Paris
Designed by the architects Marrec and Combarel,
with a Ductal ® skin.
© Lafarge Media Library - Benoît Fougeirol - Agence
ECDM - Combarel Emmanuel (Architect) - Marrec
Dominique (Architect)
Footbridge of Peace in Seoul, made of Ductal ®
designed by Rudy Ricciotti
This footbridge is made up of a very slim central arch in
Ductal ® , 130 m long, with a deck thickness not exceeding 3
cm.
Lafarge is the world leader in building materials, with top-ranking positions in all of its
businesses: Cement, Aggregates & Concrete and Gypsum. With 90,000 employees in 76
countries, Lafarge posted sales of Euros 17.6 billion and net income of Euros 1.9 billion in
2007.
Lafarge is the only company in the construction materials sector to be listed in the 2008 ‘100
Global Most Sustainable Corporations in the World’. Lafarge has been committed to
sustainable development for many years, pursuing a strategy that combines industrial knowhow
with performance, value creation, respect for employees and local cultures,
environmental protection and the conservation of natural resources and energy. To make
advances in building materials, Lafarge places the customer at the heart of its concerns. It
offers the construction industry and the general public innovative solutions bringing greater
safety, comfort and quality to their everyday surroundings.
8

SPECIFICATIONS
Production Villa Navarra (Le Muy, South of France)
Works start-up: 2007
Delivery: 2008
Area: 240 m²
Owner Enrico Navarra
Project manager Rudy Ricciotti Architecte
17, boulevard Victor Hugo
83150 Bandol
Tel. +33 4 94 29 52 61 – Fax +33 4 94 32 45 25
www.rudyricciotti.com
Romain Ricciotti, civil engineer
16 square Belsunce
13001 Marseille
Tel. +33 4 91 52 95 68
Precaster, Ductal ® slabs Bonna Sabla
Rue Aimé Bonna - BP 144
78702 Conflans Ste Honorine Cedex
Tel. : +33 1 34 90 82 56
Contact: Pierre Palot, Head of Technical Development
Ductal ® Supplier Lafarge Ciments
5, boulevard Louis Loucheur – BP 302
92214 Saint-Cloud Cedex
Tel. +33 1 49 11 40 40 – Fax +33 1 49 11 44 14
Contacts: Laurence Jacques, Technical Director
Ductal ® , Head of Development France
Léopold Lombard, Head of Architect
Relations
9

La Villa Navarra
designed by Rudy Ricciotti,
the first of its kind in the world
LAFARGE
External Communications
Stéphanie Tessier
stephanie.tessier@lafarge.com
+33 1 44 34 92 32
A Ductal® roof,
40m long with a 7.80m cantilever
Media Relations
Lucy Saint-Antonin
lucy.saint-antonin@lafarge.com
+33 1 44 34 19 47
Claire Mathieu
claire.mathieu@lafarge.com
+33 1 44 34 18 18
Architect relations
Léopold Lombard
leopold.lombard@lafarge.com
+33 1 44 34 12 91
Press kit
May 2008