Demidec cornish concrete products Demidec Flooring and Permanent Formwork
Demidec What is Demidec? Demidec is a thin precast concrete plate, typically 60mm deep, although this can vary depending on the use. The plate is supplied with a projecting steel lattice girder system that enables it to provide permanent formwork and integral tension reinforcement for insitu concrete toppings. How is Demidec made? All Demidec floors are manufactured in a state of the art carousel plant on precision engineered flat steel pallets. Shutters are held in place using magnets thereby ensuring that the quality of the pallets is not compromised. Sockets, channels and electrical boxes can be cast into the units along with conduits. Demidec is made from ecocrete, the most environmentally friendly structural precast concrete in the UK
Why choose Demidec Flooring? Flat Soffit - Demidec floors are flat and have no camber. Quality Finish -Demidec floors produce a soffit ready for direct decoration. Each plank is cast with a small chamfer along the horizontal edge. Units are nominally 2400mm wide, although this can be varied to suit the geometry of the site so that the joints between units can be expressed. Thermal Mass Effect - By choosing Demidec floors, there is no need for a suspended ceiling and thus the thermal mass effect can be maximised as the concrete soffit is left exposed. Thermal Performance - Part L1A of the Building Regulations shows a k-value of 138kJ/m 2 K from above and a k-value of 230kJ/m 2 K from below. When compared to a timber floor with a plasterboard ceiling which has k-values of 24kJ/m 2 K and 9kJ/ m 2 K from above and below respectively, the effect that the thermal mass has on thermal performance becomes apparent. This cannot be surpassed by any other form of construction. In the drive for low carbon buildings, designers are consistently selecting exposed concrete soffits as their material of choice because of its latent thermal mass. This can be further enhanced by selecting heavyweight wall construction such as CCP s Crosswall Construction including Thermowall Insulated Sandwich Panels. Sound - The density of the product reduces sound transmission. Speed of Erection - Due to the increased nominal width of units and the simple lifting arrangements, large areas of floor can be erected in a very short space of time. Cost - Demidec flooring compares favourably with the cost of insitu concrete solutions as well as providing an instant working platform and a high quality soffit.
For what applications can Demidec be used? All Demidec units have an excellent soffit finish and so are suitable for a variety of different applications: Floors for: / Residential / Commercial / Industrial / Hotels / Accommodation Blocks Permanent Formwork for: / Car Park Decks / Bridge Decks / Jetties / Water Retaining Structures / Insitu Concrete & Post Tensioned Floors What is Demidec made from? Demidec is made from Ecocrete environmentally friendly concrete which is responsibly sourced with a minimum of 80% secondary content in all products. Are Demidec floors suitable for use with different types of construction? Demidec floors are far more versatile than prestressed concrete floors as they can be adapted to suit the many different environments. For example, cover to reinforcement can be varied to suit different fire ratings or exposure classes. They can be also used as permanent formwork for an insitu concrete floor or as part of a composite solution where the reinforcement in the Demidec unit is integral to the overall design solution. Single row of props
Variations Hollow Core Applications By adding polystyrene void formers at the factory to the Demidec floors, the overall selfweight of the floors is reduced, thereby improving performance and reducing the dead load on the overall structure where the polystyrene creates a hollow core within the overall floor slab. Void formers are generally 400mm wide and are fixed between the lattice girders which are usually at 600mm centres. Lightweight Concrete Demidec can also be made in lightweight concrete using Lytag with a specific density of 1.8 compared to 2.4 of normal structural concrete. Lytag is also a waste product and hence its inclusion would not alter the secondary content of the concrete. However, if the precast is made of a lightweight concrete, the insitu topping will also need to be of a similar density. Alternatively, the precast elements can be made in normal density concrete and the poured insitu topping in lightweight concrete. On Site Demidec elements are designed to be lifted with the hooks of the lifting eye positioned under the diagonal of the lattice. Joints between elements will need to be sealed prior to the insitu concrete pour to prevent grout loss. On site reinforcement will need to be placed and insitu concreting will be carried out in accordance with the specification. More detailed technical guidance notes are available on our website, and specific technical guidance notes will be issued with each contract. www.cornishconcrete.co.uk
Is Demidec a flexible system? Each Demidec element is designed in the most efficient way for the particular part of the structure and its loadings. Sufficient reinforcement can be added to cope with localised additional point loads as well as trimming around openings. Unlike prestressed floors, the need for additional supports around openings can usually be avoided. Does Demidec always require propping? Demidec flooring and permanent formwork utilises the lattice girder which gives the units the stiffness required to take the imposed loads from the insitu concrete. Generally, the greater the stiffness required, the more lattice girders will be required. As a rule of thumb, Demidec flooring comes with three propping options: Propped Units are propped with one single row of props placed prior to the insitu concrete pour. Multiple Props for longer spans, additional props are added, typically at 2500mm to 3000mm centres - this would be designed specifically for each project. Unpropped use extra lattice girders are used in the Demidec design giving the units sufficient rigidity to allow for the insitu concrete. For Health & Safety reasons, units are generally post propped so that passive fall systems can be installed prior to the erection of the floors.
What are Demidec s capabilities? Below is an indicative load span table to be used only as a guide. Every Demidec application will be reviewed by CCP s in-house design team in order to find the solution which most meets our customers needs. Indicative Load Span Table The table shows indicative spans for each depth of slab for various support conditions. This table is based on dead loading with 0.5kN/m 2 allowance for finishes and a superimposed load of 1.5kN/m 2 150 175 200 (thick) 225 250 275 300 9.0 m span More complex span conditions and loadings can be easily be accommodated. For details please contact Cornish Concrete Products Ltd As can be seen from the graph the additional tension reinforcement improves the performance of the floor. Unlike other types of floor, Demidec s performance can be improved greatly if floors can be designed as continuous spans. There is alternate negative and positive bending along the spans and because of this, the amount of reinforcement can be reduced, which will also have its effect on cost. 8.0 m span 7.0 m span 6.0 m span 5.0 m span 4.0 m span 3.0 m span Key: Continuous multiple + increased reinforcement Simply supported span + increased reinforcement Continuous multiple spans + minimum reinforcement Simply supported span + minimum reinforcement General Structural Information Lattice girders are the essential element in Demidec flooring. They are generally placed at 600mm centres and ensure that the panels span the required distance in the temporary condition. They also assist the floor in its composite state with any top reinforcement being tied into the elements. The top reinforcement in the slab will be also designed by CCP. Progressive Collapse -Demidec flooring deals simply with progressive collapse as all the elements are tied together in a monolithic structure.
Environment and Quality CCP takes its environmental responsibilities very seriously and is accredited with the Environmental Management system ISO14001, are a founder signatory of the British Precast Sustainability Charter, and one of the first companies in the UK to be accredited with BES6001, The Code for Responsible Sourcing achieving a Very Good status across all of its product ranges. Concrete is an essential part of the built environment and with at least 80% secondary product in every cubic metre of concrete. CCP s Ecocrete provides the most environmentally friendly structural precast concrete in the UK. Increasingly, more concrete is being produced with Ecocrete Plus which has an overall secondary content of at least 85%. This commitment to environmental matters assists CCP s customers in their pursuit of BREEAM excellence. CCP is also accredited with the Quality Management System ISO9001. Cornish Concrete Products Ltd Point Mills, Bissoe, Truro, Cornwall TR4 8QZ Tel: 01872 864808 Email: info@cornishconcrete.co.uk www.cornishconcrete.co.uk www.ecocreteproducts.co.uk 009