Hybrid Concrete construction : maximising the potential of concrete by combining precast and in-situ concrete Presented by: Vincent TEISSIER, Christophe BERGER LafargeHolcim Center of Research WARNING BEFORE WE GET STARTED…. CONTENTS • Introduction • Typical hybrid options & case studies • In-house examples • • Pre-walls Concrete-wood solutions • Conclusions CONTENTS • Introduction • Typical hybrid options & case studies • In-house examples • • Pre-walls Concrete-wood solutions • Conclusions Introduction The search for greater economy, in terms of material costs and reduced construction time, has resulted in innovative approaches that seek to combine construction materials and methods to optimum effect. Hybrid construction combines the most appropriate materials and methods of construction to produce simple, buildable and economic structures which result in faster, safer construction and reduced costs. Hybrid Concrete construction combines the benefits of precasting with all the benefits of in-situ concreting Precast Concrete In-situ concrete Precast Concrete Economic for repetitive elements Long clear spans Speed of erection Buildability High quality finishes Accuracy Reduced propping on site Reduced skilled labor on site Economic for bespoke areas Continuity Robustness Design flexibility Locally sourced materials Short lead-in times Durability Economic for repetitive elements Long clear spans Speed of erection Buildability High quality finishes Accuracy Reduced propping on site Reduced skilled labor on site CONTENTS • Introduction • Typical hybrid options & case studies • In-house examples • • Pre-walls Concrete-wood solutions • Conclusions Typical hybrid options * Jubilee Library, Brighton. * From « Hybrid concrete construction » guide Some case studies * Jubilee Library, Brighton. « Ideas Store », UK. « West Quay car park », UK. Gatwick airport Toyota HQ * from « Hybrid concrete construction » guide & « Best practice guidance for Hybrid concrete construction » CONTENTS • Introduction • Typical hybrid options & case studies • In-house examples • • Pre-walls Concrete-wood solutions • Conclusions Pre-Wall System Precast twin wall system linked by steel connectors and filled by in-situ concrete No formwork, good quality finish due to precast manufacturing, structural load bearing capacity Pre-Wall System – main applications Residential buildings, offices, car parks, schools, military, etc. Industrial buildings : fire walls, technicals, etc. Miscellaneous : fences, basins, silos, waste recycling plants, sound insulation walls, etc. Pre-Wall System – technical description 2 pre-cast walls with independent dimensions (40-50MPa) Wall thicknesses from 4.5cm to 7cm Average weight 250 kg à 350 kg/m² Minimum steel reinforcement 6.5 kg/m² All steel parts integrated Pre-Wall System – a technically-challenging manufacturing process Pre-Wall System – job site management On job sites, pre-wall elements can be turned upside-down automatically (1) Full truck loads can be stored on job sites (2) Cranes are required to manipulate heavy elements (3) (3) (3) (2) (1) Pre-Wall System – filling up of pre-walls by in-situ concrete The filling operation of the pre-wall cavity with in-situ concrete should be done with care, in order to not blow-up the 2 wall elements due to hydrostatic pressure In particular, it is recommended to not exceed 70cm filling height , then allow about 1h between 2 filling operations Typical issues observed can be air pockets, segregation, etc. A recommended solution would be to use Self Compacting Concrete rather than regular concrete CONTENTS • Introduction • Typical hybrid options & case studies • In-house examples • • Pre-walls Concrete-wood solutions • Conclusions Concrete-Wood solution : a composite system associating precast & in-situ concrete + wood frames Architectural view of « Jardins de Jules » - LYON Concrete-Wood solution – description of the system (1/2) • Precast panel composed of a concrete wall + a wood frame provided to host insulation materials, linked together with elements of galvanised steel • Development driven by the thermal constraints linked with RT2012 (insulation thickness & air tightness) Galvanised steel connector Wood frame Concrete external skin Max dimensions : 3m x 5,2m Possible thickness : 280, 300, 320, 340 mm Weight/m² : 192 to 196 kg/m² Concrete-Wood solution – description of the system (2/2) Structural concept : • Column / beam for the facade • Load bearing wall for the interior wall • Cast in place solid slab Cast in place slab Cast in place column Concrete-Wood solution – addition of insulation material Exterior Rockwool insulation (95+120mm) Rockwool insulation (50mm) Interior THERMAL FLOW Concrete-Wood solution – typical job site practices (1/6) Transportation of panels on horizontal position Lifting with tower crane Concrete-Wood solution – job site practices (2/6) Elements are re-positioned vertically for handling by specific hydraulic tools Concrete-Wood solution – job site practices (3/6) Preparation of panel support on the slab Bed of sealant Concrete-Wood solution – job site practices (4/6) Push-pull props also used for adjustment of wall alignment Concrete-Wood solution – job site practices (5/6) Waterproofing membrane Rockwool insulation Steel reinforcement Concrete-Wood solution – job site practices (6/6) Plywood formwork Cast in place column supporting slab Concrete-Wood solution – job site overview (1/3) Concrete-Wood solution – job site overview (2/3) Concrete-Wood solution – job site overview (3/3) Concrete-Wood solution – key points to remember • Increased speed of construction by maximising contribution from precast • Improved safety on site, no use of scaffolding • “Clean” job sites, with limited use of formwork • Various type of finish for external skins (colour, matrix, aesthetic concrete) • High thermal insulation and air tightness CONTENTS • Introduction • Typical hybrid options & case studies • In-house examples • • Pre-walls Concrete-wood solutions • Conclusions Conclusions • Hybrid Concrete construction combines the benefits of precasting with all the benefits of in-situ concreting • To date, cost savings up to 30%* have been achieved by using hybrid construction • Looking ahead, greater potential is likely going to be achieved by combining all of these elements with fully integrated design opportunities offered by the BIM (Building Information Model) technology • Best practice guidance for hybrid construction, Goodchild & Glass use of a hybrid concrete frame instead of a composite steel frame on a shell-and-core office project in central London led to savings of 29% and increased net lettable floor area from 33,700 m2 to 38,200 m2 – (a 13% increase)11. Concept Plot of land Numerical model Structure design Services Thank you
