Sub-Base:
Before application of an Asphalt / Tarmac base, concrete or cellular grid, there should be in place the correct sub-base. This would be a minimum 150mm depth of well compacted Type 3 granular sub-base to SHW clause 805, or 4/40mm, 4/20mm crushed aggregate to BS EN12620 or locally available secondary or recycled aggregates which comply with the above specification blinded with 2/6.3mm graded crushed concrete aggregate to BS EN12620.

Concrete: 
1. Concrete bay proportions should be ideally 1:1 and should not be greater than 3:2, long narrow strips of concrete will crack across the bay width and these cracks are likely to be mirrored in the surfacing. 
2. Open bay joints are likely to cause cracking in the surfacing and formation should be prevented by application of Polycrete repair mortar into the joints. Bays should be linked with steel mesh reinforcement, or if already in place, a surface grade mesh should be embedded in the surface using an epoxy bedding coat. 
3. Ensure that the concrete has a minimum design strength of C35 and that the concrete has a minimum compressive strength of 25N/mm2 before the surface is prepared, in accordance with BS 8500-2:2015. 

Drainage:
Ensure that falls are in place to an adequate drainage system when applying to an impermeable concrete base. Water will flow through the Valtex system and run across the concrete surface.

Asphalt (Bituminous Macadam):
The bitumen binder of asphalt concrete must have a pen value no greater than 100/150, when tested in accordance with EN 1426 Needle Penetration Test. It is advisable to use a harder grade of bitumen when machine application is possible and 70/100 pen (or harder) is preferred.

Bituminous materials with a higher pen value will be too soft and may deform in warm weather. Adequate compaction of the sub-base and base is essential to prevent cracking. A minimum 1 tonne “sit on” roller should be used when possible and the contractor must ensure that the construction is fully restrained at all edges to ensure dimensional stability.

Drainage:
Rainwater will flow through the permeable Valtex Resin Bound System, and through the open grade binder course. An integral drainage system is not required.

Cellular Grid:
We would recommend to use a cellular grid of 40-50mm in depth. The grid should be set on to a well compacted sub-base as laid out above. The cellular grid should then be filled with well compacted 4/10mm graded crushed aggregate to BS EN12620. The in-fill aggregate must be compacted to ensure the profile of the cellular grid is still visible, and capable of bonding to the resin bound system. 

Failure to compact the stones within the grid correctly will result in a slump of the resin bound material through the grid, causing delamination. 

Perimeter Edging:
Protect all edges abutting soft landscaping with brick, steel, timber or concrete to prevent damage to the surfacing. Edgings should be securely fixed to prevent movement. A flexible joint filler should be used at edgings where there is potential for movement to separate the surfacing from the edging.

Concrete Preparation:
Prepare concrete by mechanical means to provide a sound, clean, dry substrate that is free from laitance and suitable for application of the resin bound surfacing. Concrete should be primed prior to application using our Easiprime or Epiprime (and seeded with a 1.4 - 1.8mm quartz).

Asphalt (Bituminous Macadam) Preparation:
Allow the asphalt to oxidise for 7 days prior to application of the Valtex Resin Bound Surface. It is not a requirement to prime asphalt surfaces.