GftK’s vdw VarioSand

Application of GftK’s vdw VarioSand

Overall project requirements: A stable, load-bearing structure and a water permeable sub-base as per national guidelines and standards for flexible block paving etc. The joint depth must be at least 40 mm, with the width at least 2mm, up to max. 4 mm. Application is best done in Spring and summer in order to ensure that the ambient and substrate temperatures are min. 8° C, max. 30° C. After installation, a frost-free period of at least two days is also essential.

Test area: On some sensitive reconstituted stone (concrete) pavers, dry contact with vdw VarioSand can change the appearance of the stone (foggy / slight discoloration). Therefore, we always suggest an inconspicuous test area first!

Tools & equipment:

• Coconut fibre brush
• Squeegee
• Big rubber mallet (for areas that cannot be treated with a wacker plate)
• Water supply hose with an adjustable spray nozzle
• Sponge, for edge finishing where necessary
• For new block paving installations: “big” wacker plate (if necessary equipped with a screen mat, depending on the type of sub-base stone)
• Otherwise for refurbishment use a suitable “small” wacker plate (e.g. one that is about 60-80 kgs) to vibrate the block surfaces and compact the vdw VarioSand into the joints.

Surface Preparation: Clean the surface and ensure the removal of all dirt, cement residues, organic materials, or any other contaminants, including raking and thoroughly cleaning out all the joints to the required depth. The paved surface and the joints themselves must be absolutely dry, otherwise the binder of the vdw VarioSand will be activated too soon and this could also lead to discoloration of the paved surfaces. If necessary, remove any residual moisture using a gas burner.

Filling the joints: Brush in the vdw VarioSand until the joints are completely filled. Brush off the surface and compact the material by using a suitable wacker plate. Smaller areas may be vibrated/compacted with a rubber mallet. Be sure to compact the material thoroughly in order to achieve a solid and durable result and repeat this procedure to excess and the required filling height is achieved. Test the sand compression with a finger to ensure that the material is firm and solid. The joints should generally be filled up to max 2 mm beneath the top surface and any chamfers must be brushed free before activating the binding agent. Finally, brush off the surface with a soft, clean and dry brush so that no residues are left.

Activation of the binding agent: Wet the surface thoroughly with clean water using a soft spray nozzle indirectly and in small sections, always beginning from the lowest point of the falls. Repeat this procedure 4-5 times, until the jointing material is saturated with water in its full depth. Avoid washing the vdw VarioSand out of the joints. Do not use strong water jets, or hold the nozzle too close, or directed at the joints, in order to avoid excess water and/or foaming of the binding agent. Ensure that the paved surface remains damp and does not dry out during this process.

Testing: Check if the jointing material is completely saturated with water at several points by using a screwdriver or a spatula (just lift the sand and put it back again into the joint after examination). Avoid any water ponding and remove any free-standing water using a sponge or squeegee.

Post treatment: The following relates to an average temperature of 20 °C / 68 °F and 65 % relative humidity. Higher temperatures will shorten the curing period, lower temperatures will increase it. GftK’s vdw VarioSand must be allowed time to completely dry and harden to achieve the perfect result. For this reason, we strongly recommend that the material is ONLY APPLIED in warm, dry and sunny weather. Protect the freshly jointed area against rain or water run-off for at least min. 3 hours but check and prolong this protection in case of lower temperatures e.g. overnight and/or high humidity’s as can happen in the British Summertime!! In dry weather conditions it is not necessary to cover the surface so that the material may perfectly harden. The finished area must not be walked on for at least 3 hours and it may only be driven on by light vehicles after 3 to 5 days depending on the conditions etc.