Lightweight concrete pumped up 75 metres

In May and June 2009, Camfaud Concrete Pumps carried out a contract to pump lightweight concrete to a height of 75 metres on the iconic Kodak Building in the centre of Hemel Hempstead, Hertfordshire.

As part of Dandara Ltd's scheme to refurbish the building and convert it into apartments, four additional floors were added. To reduce the loadings, the design called for composite floors using metal decking and lightweight concrete.

Camfaud supplied their Putzmeister M66/63 pump, the largest mobile pump available in the U.K. The boom reached up to the 16th floor and the booms pipes were then connected to a fixed pipeline which fed into the building and up to the 19th and subsequently 20th, 21st and 22nd floors.

The pipeline was built up using 125 mm pipes and long radius bends in order to keep the pumping pressures down to a minimum. A gate-valve was installed in the line to aid cleaning at the end of the pour.

Hanson Premix supplied the lightweight concrete from their local plant. To ensure that the concrete would pump to the top of the building without stiffening under pressure, Hanson pre-soaked the Lytag for two days prior to each pour and used a pump-aid and super-plasticiser admixtures in the mix.

At the start of the pour, Hanson supplied 1 ½ m3 of grout to prime the pipeline before the pumping operation commenced. In the event the concrete pumped without a problem with 200 bar hydraulic pressure / c. 55 bar line pressure being the maximum pressures experienced.

During each pour, the pipeline was broken back towards the riser pipe and each discarded pipe and coupling set cleaned ready for the next pour.

On completion of the pour, a sponge ball was inserted into the riser and the pump set to reverse pumping to pull all of the concrete out of the line. Another sponge ball was then inserted into the riser and sucked back to ensure the line was completely clean, free from concrete and grout.