King’s Cross has been undergoing major redevelopment for more than a decade, with commercial and residential buildings transforming the area. More recently, new life science laboratories have been developed by Ardmore, with architects Bennetts Associates taking inspiration from The Arbour in Walthamstow and proposing the use of Site Strocks made from London clay excavated during piling and basement works.

HG Matthews processed the clay using tooling developed for the Site Strocks programme, creating the required material mix. This was the first project to carry out extensive testing of off-site material, including compressive and flexural strength testing of both the blocks and clay mortar, as well as fire testing.

Following successful testing, Site Strocks were used to construct 6m-high non-load-bearing basement walls in place of conventional concrete blocks. The clay blocks provide thermal mass while helping to regulate humidity and support improved internal air quality.

The project also demonstrated how Site Strocks can be successfully incorporated into large-scale construction. HG Matthews worked closely with contractors throughout the process, including providing practical training for the blockwork subcontractor at the factory. Where installation challenges arose, such as fixing bike racks to the clay blockwork, suitable solutions were developed collaboratively.

Using site-excavated material at this scale in central London demonstrates the potential for lower-emission, circular building materials to be incorporated into major construction projects.