A new tram stop on the Manchester Metrolink system was completed in record time thanks to the low weight, high bulk attributes of Leca® Lightweight Expanded Clay Aggregate.
This lightweight aggregate was used as fill below the platform surface where the substrate was found to be particularly soft and unstable.The use of Leca® Lightweight Expanded Clay Aggregate enabled the platform structures to be constructed from concrete sections and quickly and easily filled with the lightweight aggregate.
The Manchester Metrolink began operating in 1992 and is currently undergoing a major expansion. The existing three lines which converge in Manchester City Centre will expand to seven by 2016 taking the current length of 23 miles up to 60 and daily rider volume from 56,000 to 190,000. The number of stops will expand from 37 to nearly 100 by the time the expansion is fully open. The latest at the Abraham Moss Leisure Centre required the use of Leca® Lightweight Expanded Clay Aggregate.
Lawrence Bush of main contractor Spencer Limited managed the design project for the new tram stop, he said “Our ground condition survey found that a big peat layer, some seven or eight metres below the surface, indicated that piling would be required. The time and cost factors of piling did not fit well with the overall expansion plans of the network. The best alternative was to use Leca® Lightweight Expanded Clay Aggregate which gave us the fill capability without the weight penalty of traditional fill that would have been unstable on the poor substrate land where the platforms run. I had used Leca® Lightweight Expanded Clay Aggregate previously and knew the advantages.”
Each of the two platforms runs for 38 metres and the formwork was constructed quickly from pre-cast sections and blockwork. These were easily filled by bulk delivery of Leca® Lightweight Expanded Clay Aggregate which was loaded into place and compacted. A stone and tarmac capping completed the platform construction.
Leca® Lightweight Expanded Clay Aggregate 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 1150°C. 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 300kg per cubic metre. Leca® Lightweight Expanded Clay Aggregate has excellent insulation properties, is free draining, fire resistant, frost resistant and chemically inert with no hazardous properties. Used as a lightweight aggregate fill in many civil engineering applications Leca® Lightweight Expanded Clay Aggregate reduces the weight on weak substrates and against retaining structures can reduce the weight loading by 75% over traditional fill. Leca® Lightweight Expanded Clay Aggregate 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.
Expansion of the Manchester Metrolink system continued and Leca® Lightweight Expanded Clay Aggregate was used for further platform construction.