S and B eps

900 cubic metres of S and B Fill 45 EPS were used as light weight structural void formers in the construction of the new Newcastle City Library foundations. Grids of heavily reinforced foundation cages were built up from a concrete blinded base with the blocks of EPS packed tightly between them. Structural voids typically 10m x 6m x 1.5m deep were formed, against which the foundation concrete was poured. The area was then capped off with a structural concrete floor slab.

Several different schemes were considered for the foundations but it was felt that using EPS would give a number of advantages:

• It simplified the slab DPM tanking details.
• Tanking could be progressed earlier and independently of other construction activities.
• Reinforcement cages could be progressed earlier with improved outputs due to the improved access.
• Reinforcement was kept clean, as there was no interface with granular materials.
• Casting structural concrete against the face of accurately cut blocks of EPS eliminated the need for formwork and afforded minimal wastage.
• The logistics of bringing bulky fill materials on to a tight inner city site were eased and the plant and time that would have been required to place traditional granular fill materials were reduced.

Other benefits were the elimination of fill settlement, improved under floor insulation values and the use of 100% recyclable product assisted in compliance with the Waste Resource Action Plan.
By using expanded polystyrene blocks as lightweight structural void formers within the foundation scheme, the project achieved significant buildability, programme and cost benefits.