Adswood Recycling Centre, Stockport

Leca® LWA was used to speed up the construction of a new household waste recycling centre at Stockport, constructed by Costain, for the Greater Manchester Waste Disposal Authority. The roadways between the recycling skips needed to be raised two metres above the land surface. The wall sections were constructed as a u-section and the Leca® LWA fill placed in the U-section to a depth of 1.8 metres. This was capped with MOT type 2 material and C1 concrete. Leca® LWA was chosen for speed and ease of fill and for the low weight which reduced pressure on the retaining walls of the construction. Service ducts are securely buried in the Leca® LWA to avoid risk of deformation by traditional fill materials. Leca® LWA is a totally natural product. It is lightweight expanded clay formed by heating and firing natural glacial clay in a rotary kiln at temperatures up to 1150oC. This process transforms the clay into lightweight ceramic granules with a hard ceramic shell and porous core. The material is extremely light with a bulk density of just 0.3 tonnes per cubic metre. Leca® LWA has excellent insulation properties, is free draining, fire resistant, frost resistant and chemically inert with no hazardous properties. Used as a lightweight fill in many civil engineering applications Leca® LWA reduces the loading on weak substrates and against retaining structures by 75% over traditional fill. Leca® LWA eliminates expensive settlement delays, is easily handled and quickly installed. It is particularly valuable in stabilising slopes where the ceramic granules interlock together and fix the terrain for safety. The nine-month construction programme of the Adswood Household Waste Recycling Centre at Stockport called for the roadway construction to one of the final sectors and the Leca® LWA was delivered by walking floor bulk transport and placed by mechanical shovel which was also used to track and compact the material into place. For this project speed of delivery and application was of great importance as the Recycling Centre remained open during the construction, and health and safety for the visiting public was a major consideration. Equally, due to the restricted access and tipping area the walking floor vehicles were given little or no tolerance. The narrow ramps were confined on both sides with concrete walls which called for precision and accuracy in order to safely reverse the vehicles into position. 2410m³ of Leca® LWA was used in this project at the Adswood Household Waste Recycling Centre.