Millau Viaduct
Transcription
Millau Viaduct
8837_FICHE_CHANTIER_LOT1_5 23/06/08 16:42 Page 42 Country: France Dates of realisation: Late 2001 - Decembre 2003 Public opening: Decembre 16th, 2004 Millau Viaduct CHRYSO®Fluid Optima 175 Project Concrete formulation • Total volume of concrete • Geographical situation Construction of the Millau Viaduct, constituting the last stretch of the A75 motorway. It enables Clermont-Ferrand to be reached directly from Béziers, therefore avoiding the Millau traffic bottleneck. It also is the most direct and cheapest route between Paris and the Mediterranean sea. The viaduct of Millau is longer and higher than the bridge of Normandy, and crosses the Tarn River to the West of Millau. There were numerous constraints to this construction site : • geological (protected natural zone), • climatic (winds, important temperature changes), • geographical (in between two valleys). • Details of the project Admixture used CHRYSO®Fluid Optima 175 Results A wide scale of dosage according to the types of concrete produced: 0.4 % for a B35 up to 1.4 % for a B60G. Production of consistent quality of concrete while still achieving the rheological and mechanical characteristics required, even with major variations of the outside temperatures: below 0 °C in winter with hot concrete and above 35 °C in summer (profile taken from the 2003 heat wave), with protected constituents. A homogeneous, non viscous concrete which facilitated pumping and improved pouring into formwork. With a length of 2,460 metres and piles peaking at 343 metres, the viaduct of Millau is a world record in height and a technical challenge. Its particularity lays in the choice of a metal deck, supported by cable stays and based on concrete piles, and on the fact that they were all set up separately. There were 9 separate construction sites on this jobsite: the 7 piles were poured simultaneously, while the deck was mounted separately. • A few figures • 2,460 m: Total length of the deck • 7: Number of piles • 77 m: Height of the shortest pile • 250 m: Height of the highest pile • 87 m: Height of each pylon • 154: Number of cable stays • 4.20 m: Deck thickness • 32.05 m: Deck width • 85,000 m3: Total volume of concrete on the jobsite • 36,000 tons: Weight of the metallic structure 80,800 m3 • Only one admixture for 3 specifications CHRYSO®Fluid Optima 175 allowed the formulation of different types of concrete, thus meeting geological, climatic and geographical constraints. Construction was spread over 3 stages: Casting of the Morrocan wells (foundations): 8,000 m3 of concrete • B35 with 100% of grinded aggregates and 300 kg of binders (containing silica fumes) • Slump: 15 ± 3 cm • Workability retention: 90 min • Average compressive strength at 28 days > 50 MPa • Resistance to tension at 28 days > 4 MPa Base sections (grounding under each pile and temporary bedplate): 22,300 m3 of concrete • B35 for civil engineering, with silica fumes • Slump: 13 ± 3 cm • Workability retention: 90 min • Compressive strength at 28 days > 50 MPa • Casting of each bedplate: 24 hours non stop The piles: 50,500 m3 of concrete • Cement : 420 kg of CEM I 52.5 N PMES CP2 from LE TEIL • Concrete without silica fumes in order to obtain the clearest possible surface finish aspect • B60 resistant to frost, with a flowing consistency (requirements of the Groupe Rhône-Alpes (GRA)) • W/C: 0.335 • Slump at the DIN table: 50 ± 5 cm • Workability retention: 90 min • Average compressive strength at 12 hours at 20 °C: 3 MPa • Compressive strength at 17 hours: 29 MPa • Compressive strength at 28 days > 75 MPa • Tensile strength at 28 days > 6 MPa Project participants • Owner: Millau Viaduct Eiffage Company (MVEC) • Project manager: Setec • Architect: Lord Norman Foster Pictures: Eiffage TP • Company: EIFFAGE TP group • Concrete supplier: SATM - Bétons Chantiers Prêt (Lafarge)