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Large area pours for ground-supported floors

There are two major benefits from constructing floors using large area pours and using sawn grooves to form induced joints; these are speed of output and the avoidance of the many formed joints necessary when strip construction is used. For mechanised construction of large area pours ´Laser Screed´ machines that spread, compact and level the fresh concrete are now often used. The finishing boom is controlled to a precise level by hydraulic systems controlled by a laser beam signal. Typically areas of 1,000 to 2,000 m² or more of slab can be laid each day with this equipment.

Large area pours can be manually laid using superplasticised, self-compacting concrete. Concrete is brought to good level using a laser level control and surface levelling staffs with laser receptors. This is known colloquially as a ‘flood pour’ method.

Some specialist techniques can be used for large area pours, for example, where levelling rails are temporarily set up and used with vibrating beams and surface screeds in levelling the concrete. Large area pour slabs are commonly reinforced with steel fabric or steel fibres, with sawn induced contraction joints at about 6m centres. Alternatively, more heavily reinforced slabs can be laid ‘jointless’.

All large area pour slabs are finally finished, smoothed and polished using power-floats and trowels.

Acknowledgement: Concrete Society

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Concrete for industrial floors
- guidance on specification and mix design - GCG1

TR34 Concrete industrial ground floors
a guide to design and construction - 4th Edition