Articles & Case Studies

Wessex finds the answer in EPS

Posted: Tuesday 4th March 2008

As part of upgrading its pipe network, Wessex Water commissioned engineering consultancy Faber Maunsell to upgrade ductile iron pipework with new High Density Polyethylene over a 750m length along an old ‘drove’ track in Langport near Taunton. The track runs across a low lying flood plane adjacent to the river Perrett where the ground conditions are mainly peat. As such there was a significant risk of settlement in the new pipe if it was laid directly in its native ground.

Vencel Resil’s expanded polystyrene fill product Fillmaster was specified as a underfill material to reduce the overburden on the pipes, ensuring they would not deflect beyond their design limits.

Fillmaster provided the buoyancy required to prevent the pipes settling when full with water. Faber Maunsell carried out an assessment of the amount of Fillmaster required to counteract the weight of the pipes when filled with water and selected Fillmaster Type FM200 in 300mm thick blocks.

Adrian Walker, technical sales manager at Vencel Resil, explains: “This was an innovative solution to what could have caused a major problem. Fillmaster has a very high strength to weight ratio and it will provide a secure backfill for the pipes and prevent settlement. EPS is a tried and trusted material that is used in many civil engineering applications and we are confident will provide a highly effective solution.”

Andy Woods from Faber Maunsell said: “Fillmaster was well suited to this project because of its low density fill qualities and its ability to withstand imposed loads from vehicles passing over it. Where traditional fill materials would have resulted in a net material weight gain resulting in differential settlement, Fillmaster will help ensure the structural integrity of the pipes over their 80 year design life.”

Expanded polystyrene provides a lightweight alternative to traditional fill materials, which was particularly appropriate in this application. Many civil and structural engineers are finding that expanded polystyrene provides a stable, reliable material, where exceptional performance, strength and integrity are required.

In addition to its physical properties, expanded polystyrene is easy to handle, environmentally stable, HCFC-free and non toxic.The material is also extremely versatile as its closed-cell formation inhibits absorption of water and therefore avoids all of the problems of waterlogging and drainage that are associated with other fill materials.

Adrian Walker continues: “Expanded polystyrene enables civil engineers to turn their design concepts into reality. It is quick and simple to install and its high strength to weight ratio delivers a multitude of benefits which are contributing to the success of many civil engineering projects.”

Expanded polystyrene (EPS) has been used for over 30 years in road construction, for bridge abutments, bridge underfill, noise bunds, retaining walls, soft and hard landscaping and a whole host of other civil engineering applications.

For more information, contact Vencel Resil on 0870 600 3666 or visit the website

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