Site report: Insulating concrete formwork house for Nottingham Uni

In September 2006, Camfaud supplied an M24 mobile concrete pump to construct the basement in the first of the homes on the University of Nottingham “Creative Energy Homes” project. This project is intended be a showcase of innovative, energy efficient homes of the future. The six homes constructed in the University Park will be designed and constructed to allow the testing of different aspects of construction including layout and form, cladding materials, roof structures, foundations, glazing materials, thermal performance, building services systems, sustainable / renewable energy technologies, lighting systems, acoustics and water supply.

The project aims to stimulate sustainable design ideas and promote new ways of providing affordable, environmentally sustainable housing that are innovative in their design. The basement in this house was constructed using Insulating concrete formwork (ICF). This system uses expanded polystyrene formwork to build an in-situ concrete structure. The formwork is then left permanently in place to provide thermal and acoustic insulation. It also acts as a backing for plasterboard on the inside, and a brick, timber or render on the outside.

Insulating concrete formwork consists of either pre-formed interlocking blocks or separate panels with the front and back faces connected with polystyrene or plastic ties. Although all ICFs are identical in principal, the various brands can differ widely in their detailed design. At the start of the concrete pour, the pump is primed with a cement/water grout. It is good practice on every job to pump this grout to waste and this is especially true when placing concrete into an ICF structure. A good pump mix concrete with 10 mm aggregate is usually specified and it is preferable, if using 10 mm aggregate and the mix allows, to reduce down to a 75 mm end placing hose .

For an ICF pump pour to be successful the formwork has to be well braced and it should be filled with concrete slowly to minimise the risk of movement or damage. When working the end placing hose, the contractor should constantly move the hose up and down the line of the form spreading the concrete evenly. This will reduce the local pressure caused by the falling concrete. The pour should be treated as a controlled pour with the concrete being built up in layers. This can reduce the hydrostatic head as the lower layers of concrete will be stiffening as the upper layers are being poured.

• Pump: M24

• Customer: Logix UK

• Site: Nottingham University

• Concrete Supplier: Hanson Premix

• Date: September 2006