Large quantities of concrete were utilised in these warehouse, chiller and freezer floors to a design worked out in close liaison with the Engineer, Crouch, Hogg and Waterman, which was based on the optimisation of factors such as reinforcement design, concrete shrinkage and material costs. This resulted in a floor with an average in-situ shrinkage of 0.02% and an extremely hard wearing surface. The actual shrinkage values were measured in-situ by fixing Demec pips to the surface in 100 metre runs at 1 metre centres and gauge. In all, over 8000 readings were taken to measure the in-situ shrinkage.
Topmix developed Toproc LS utilising specially selected aggregates and specially imported admixtures to produce a high-performance concrete with an average 28 day strength of over 85 MPa and a slump of 150mm which could easily be pumped into place and provide a conventional 2 hour workability life. The mix did not bleed and provided a predictable final set. Some of the concrete was placed by direct discharge, but the same formulation was also pumped. The concrete was compacted by a vibrating poker and the surface levelled and closed with a rolling tube striker. The final category SF1 finish was produced by power trowel/float.
The average time from the start of each bay to the final finishing was 18 hours and the rapid in-situ strength development providing 30MPa in 24 hours, enabled the contractors to traffic the floor the following day and continue construction far sooner than is normally possible.
Product Used: Toproc LS ready-mix concrete
Beneficial Features: Low shrinkage, high abrasion resistance, very low whole life cost
Average In-situ Strength: 85 MPa in 28 days
Typical Total In-situ Shrinkage: 0.02%