Solution Features and Benefits
• High dosage of Steel Fibres means no Saw Cuts required
• Reduction in floor maintenance costs
• No Joints = less risk of Curling and better flatness
• Better flatness = less maintenance for trucks
• No Joints = better flexibility warehouse use
• Highly recommended for Cold Store and Freezer floors
• No Joints = less Risk of Load Transfer problems occurring
• The perfect solution for slabs with very heavy loading or requiring very high tolerances.
Design and Specification
If soil conditions are suitable for a SOG, using higher dosages of Steel Fibres – typically 35-45 Kg/ m3, Free Movement Joints can be spaced up to 50 m apart in each direction and Saw Cut joints can be eliminated. Steel Fibre dosage will depend on slab loading and spacing of Free Movement Joints.
Minor cracks will occur in the slab due to Drying Shrinkage but the slab design and Steel Fibres will ensure that these are well distributed throughout the slab and that the crack width is so negligible that cracks will not cause serviceability problems or maintenance concerns. As design is specialised, it is recommended that the Steel Fibre supplier or Flooring Contractor takes responsibility for the design and the Client is advised to check the Professional Liability insurance is adequate.
With the JF-SOG solution, Free Movement Joints can be expected to open up by up to 25 mm. A good quality Armoured Joint system is therefore essential to prevent damage to the slab edges at Free Movement Joints and the Clients Representative should ensure that the Dowel system has been designed for such opening and the floor designer has carefully checked the load transfer.
The increased opening of the Armoured Joints means that the Construction Joints should be carefully pre-planned and agreed with the Client and racking supplier. If the racking layout cannot be fixed at time of floor construction, the Client should be aware that racking legs should not be located either side of an Armoured Joint when full Drying Shrinkage in the concrete has not been achieved.
Due to the high dosage of Steel Fibres, a Dry Shake Hardener is critical for a JF-SOG floor in order to reduce the number of fibres exposed at the surface.
Methodology
Generally the floor construction methodology follows that for a Jointed SOG, although in order to ensure that the Client can enjoy the long term benefits of a Joint Free floor, it is particularly important that standards of Quality Control are as high as possible. As there are no Joints, it is even more important that the Sub-Base is constructed as flat and level as possible. As with the LP-SOG, CoGri Korea’ Engineers will supervise the Sub-Base preparation and carry out a complete survey of levels on a 3 m grid to ensure that the required tolerance of +0, -25 mm is achieved.
Due to the larger joint opening expected in the Free Movement joints with a Joint Free slab, the quality control and mix design of the Concrete is especially important. As always the CoGri Korea Engineer will select a Concrete Supplier which has the best locally available constituents and the highest standards of quality control, do detailed trial mixes and ensure thorough Quality Control checks at all stages of the Concrete batching and delivery. The Steel Fibres can be added to the Concrete at the batching plant during mixing or at site using a conveyor or Fibre blower, depending on the dosage and type of Steel Fibres and condition of Concrete Mixer trucks.
The concrete is placed and screeded level using the CoGri Korea S-240 Laser Screed as with a LP-SOG. With the experience and technical expertise the CoGri Group has in constructing ‘Superflat’ floors, CoGri Korea is able to apply specialised techniques to construct JF-SOG floors to very high tolerances of up to TR-34 ‘Category 1’, for VNA Warehouses. Additionally being Joint Free which eliminates the concern of Curling at joints, the Client can be confident that the floor will remain flat in the long term. A Dry Shake Topping should be applied at a dosage of 4-5 Kg to suppress the Fibres at the surface of the slab; Spreader above
Coloured Dry Shake finishes can be provided if necessary, although the Client should understand that the colour will be somewhat variable. It is highly recommended that an Automated Topping Spreader is used to apply the Dry Shake Topping as early as possible, which reduces the risk of any delamination occurring due to mistiming.
