Floors are like icebergs. They seem harmless enough but hide a lot of potential problems if neglected, or worse still badly installed. Neglect can take various forms, like ignoring damaged floors from uneven joints and potholes to poor, inadequate cleaning regimes, all of which impact safety, MHE equipment damage and even damage to racking and stored goods cause by skidding forklifts on slippery floors. Despite the legal duties to maintain safe working conditions, floor-related accidents occur all too often.
Floor flatness is a prime concern and so the ideal floor would be perfectly flat and level and have no joints. This is particularly so for high bay VNA stores where a few millimetres of uneven floors would be magnified many times at heights over 12 mt, risking collision between trucks and racking. ‘Perfect’ floors are more achievable with a ‘jointless’ steel fibre reinforced concrete floor slab because it dispenses with saw-cut joints. These joints are likely to curl and breakdown at the edges and so could slow order picking speed significantly and raise operator discomfort. With a ‘jointless’ floor any joints are governed by the limit of each day’s concrete pour.
If, however, faced with uneven jointed floors there are five remedial measures but with variable results. There are a few possible reasons behind loose floor joints but the main cause is the lack of effective load transfer across the joint. To achieve a well-designed floor designers will specify load transfer mechanisms, typically dowel bars or steel reinforcement, both of which have a good record of success, says Alan Yuill, director of CG Flooring Systems. A loose or rocking joint has little or no effective load transfer capability, often the product of designers or contractors not installing a load transfer mechanism or an inadequate one.
Of the five remedial options, total floor replacement is rarely done. The sub-slab grout injection option does not address the root problem of poor load transfer and so at best is a short-term fix. The retrofit dowel solution when done well can provide very effective load transfer. This involves making saw cuts in the slab across the joint, cutting about half way through the slab thickness. The dowel bars are placed in the slots and locked in with a strong mortar. A fourth option is full depth joint replacement. The fifth option is the CoGri joint stabiliser that provides similar results to those from dowel bars and can reduce vertical differential to less than a millimetre. It is less disruptive than any other joint stabilisation repair method and often more cost effective.
If cursed with a particularly bad case of floor dishing resulting from poor sub soil load bearing qualities the solution is no longer horrifically costly and disruptive. Previously, the answer would have involved pile driving but now foam injection techniques like those from Uretek are far cheaper, quicker and almost disruption free.
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