Freyssinet introduced post-tensioned concrete building floor slabs to the UK in the early 1980’s. Since that time they have championed post-tensioning technology and contributed to its acceptance as a standard system of construction.

Offering a full service package, their in-house design team can support clients from conception through detailed design and site installation utilising experienced site managers and operatives. Freyssinet sets high and specified performance criteria positioned above the usual industry standards.

Last year Freyssinet successfully completed a number of post-tensioned slab contracts for the construction of schools and colleges throughout the UK. These included: • The Learning Centre, Ebbw Vale Campus, Wales • Bourneville College, Birmingham • The Big Build, Rutland • Orminston Academy, Birmingham • Sir Robert Woodard Academy, Lancing

Freyssinet have recently been awarded further post-tensioned floor slab contracts for Wade Deacon High School in Widnes and the Learning Resource Centre at Stafford College. Freyssinet first got involved with the Wade Deacon project over a year before it was finally let, working with VINCI Construction to give cost advice on a concrete alternative to the then conforming steel framed structure with precast concrete flooring units. The post-tensioned alternative saved significantly on the build cost and the flat soffits assisted the architectural planning and services layout. The structure consists of a spine block running the full length of the 106m long historic façade. Springing from the spine are three teaching wings, each comprising an atrium bounded by classrooms on either side. The three storey structure has 9,750m2 of suspended PT slabs, all being 230mm deep, each floor will be concreted in six pours. The post-tensioning system selected by Freyssinet’s in-house design team is the 4B13 bonded system. At level 1, two 1000x350mm deep PT beams have been used to span up to 13.7m to allow a pair of columns to be omitted thus creating a feature access way. And on the roof level the same sized PT beams cantilever 3.3m thus avoiding having to run columns down through teaching space below.

Post-tensioned concrete is an ideal choice for academic building construction. It reduces the depth of the structural members meaning the floor to floor height is reduced. Post-tensioned concrete also has excellent deflection control due to the inbuilt parabolic profiles of the tendons, which directly counter deflection effects. There is plenty of experience within Freyssinet of building post-tensioned concrete academic buildings. The majority of these have been designed and detailed by our in-house team of qualified and experienced engineers and technicians. Post-tensioning provides a great many advantages, including: • Increasing spans and load carrying capacity; • Reducing slab thickness; • Eliminating beam downstands; • Reducing self weight, quantities of materials and loads on foundations; • Considerably reducing and simplifying passive reinforcement; • Reducing the number of expansion joints and columns; • Better punching shear characteristics; • Outstanding behaviour in seismic zones; • Increased cracking resistance; • Increased waterproofing due to concrete compression; • Reduced excavation in basements; • Deflection control; • Removal of the formwork within 3 days; • Environmental benefits, less concrete, less steel, fewer lorry journeys. The environmental credentials of post-tensioned construction are one of the major selling points when the client’s team are trying to determine the construction material. Typically, post-tensioned slabs save about 25% of the slab depth and hence 25% of the concrete volume, when compared to the Reinforced Concrete (RC) equivalent. The steel content (reinforcement and post-tensioned combined) is often reduced by 65%. In addition to academic buildings, post-tensioning also suits a wide variety of projects, such as: • Offices • Retail developments • Underground car parks and multi-storey car parks • Hospitals • Business centres • Industrial buildings • Sports buildings • Residential towers