Propump_Royal_Exchange Filling Tunnels, and James Henry Greathead

Filling Tunnels, and James Henry Greathead


In front of the Iconic Royal Exchange, Propump prepare to pump specialist foamed concrete into a network of passageways in London’s Underground, during engineering hours. To the right of the photo is a statue of James Henry Greathead (1844 – 1896), Inventor of the “traveling shield” (1869).

The Greathead shield made significant technological improvements over Brunel’s square shield design which allowed the current style of subterranean tunnelling to develop, modern day tunnelling practices still use this basic principle.

Comprising a circular ring which was propelled forward on screw jacks (later hydraulics) it used cast iron rings to make the new tunnel safe whilst the digging face was propelled forward to continue the cutting and material removal. Additions to the design also included water jets to remove loose soil form the digging face as a slurry of material.

James Henry Greathead also successfully patented and used various other ground breaking innovations such as using pressure differentials to reduce the likely hood of collapse (subaqueous tunnelling) , as well as the first form of pressure grouting, used to stabilise overhead soil, as wells as the precursor to shock-crete.

Foamed concrete has a great number of potential uses. The fluid nature of this Foamed cement / grout combination allows it to be pumped much easier and at considerably less pressure than conventional concrete mixes. This allows a sufficiently fluid foamed concrete with no large aggregate to fully minimise any voids or gaps without the use of vibration or tamping.

Foamed concrete is a non-structural material used to rapidly fill voids which could present safety risks. For more information about how Foamed concrete could be used in your project, please call the office on (+44) 01322 429 900