Holland Park School | London

Access to remote void fill in London School

The £58m new build replacement of the original 1958 Holland Park School in the Royal Borough of Kensington and Chelsea, London, required the attributes of Leca® Lightweight Expanded Clay Aggregate in the second phase of the three-year build project, for its pool complex located deep in the basement area.

This location presented a major challenge to main contractor, Shepherd Construction and sub-contractor, Getjar Ltd. 150m³ of back fill material was required to fill the perimeter to the pool below the walkway capping. The position of the pool is so far away from external access that any form of mechanical delivery was impossible and the use of wheelbarrow delivery was a daunting prospect!

Leca® Lightweight Expanded Clay Aggregate proved to be the successful solution, both in terms of material and delivery, recommended by pool manufacturer Barr + Wray and approved by engineering consultancy Buro Happold. The material was blown into position by the Leca® Lightweight Expanded Clay Aggregate pneumatic delivery unit, through a complex combination of rubber and steel concrete delivery pipes more than 60metres long.

The Leca® Lightweight Expanded Clay Aggregate was blown from the unit sited outside the premises to the pool perimeter via a complex route along corridors, around corners and down flights of stairs! Getjar Ltd provided a 5-man team to ensure smooth and efficient delivery and installation.

The pneumatic unit arrived pre-loaded with 60m³ of material and subsequent make–up loads were delivered by a rigid tipper and stored adjacent to the unit ready for reloading, in a purpose built bay to protect it from contaminants.

Over two days this system delivered the material directly into position, to form a stable void fill before the walkway capping was installed. A totally natural product, Leca® Lightweight Expanded Clay Aggregate is 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 shell and porous core. With a bulk density of just 0.3 tonnes 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 and construction applications Leca® Lightweight Expanded Clay Aggregate reduces the weight on weak substrates and against retaining structures by up to 75% over traditional fill and eliminates expensive settlement delays, is easily handled and quickly installed.

Glenn Lesurf of Shepherd Construction commented. “The pneumatic delivery of the Leca® Lightweight Expanded Clay Aggregate saved days and days of labour intensive expense and allowed us to keep the pool project moving along on schedule. In two days, we completed the void filling and could continue with the walkway capping to deliver this part of the project on time.”