● TARMACADAM – FULL INSTALL
Application to a new open-graded tarmacadam/bitmac surface

Newly laid, open-graded tarmacadam with a pen value between 70 to 100 (never exceeding 100) is the ideal base course for a long lasting, high performance resin bound surface. If the tarmacadam/bitmac surface is to be laid as part of the resin bound groundworks then the specifications listed in the substrate specifications section of this document should be consulted. No bituminous base should ever be less than 50mm in depth, the tarmacadam/bitmac should always be open-graded, comply with BS4987 and be given a minimum of 7 days to cure before the application of the resin bound surface.

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IMPORTANT:  It is desirable to keep the time between the tarmacadam/bitmac base being installed and the surface layer (such as resin bound) being applied to it as short as possible however, not allowing a sufficient cure time can result in system failure. Strictly speaking, a bituminous surface relies on thermal transfer, oxidation and solvent evaporation rather than a specific chemical reaction cure although the time taken for a bituminous surface to become solid is still referred to as the ‘cure time’.

Although uncommon, tarmacadam surfaces can have problems with curing and this can result in the surface remaining soft or tacky for much longer than expected. The keys reasons for this can be the use of an unsuitable PEN value binder, the use of a poor-quality solvent or climatic conditions delaying the evaporation of the solvents. If the resin bound surface is applied prior to the base achieving full cure, any problems with the tarmacadam installation may not become apparent for weeks or even months after completion. If solvents within the base course have not sufficiently evaporated this can manifest itself by attacking the resin surface and is often mistaken as water damage due to the whitening effect it has on the bound surface.

Star Uretech recommend that a new tarmacadam/bitmac surface is given ten days (a minimum of seven days) to cure before a resin bound surface is installed. It can take up-to seven days for the majority of the system’s volatiles (solvents) to evaporate and a further four to twelve weeks for full oxidation to occur. After 10 days there will only be trace levels of volatiles remaining and any oils on the surface will have oxidized making it suitable for a surface coat.

A resin bound surface laid on to a tarmacadam/bitmac base which has not been given seven days to cure may initially look unaffected however it can result in the underside of the bound surface becoming soft due to solvent egress, delamination due to oil contamination between the surfaces and whitening/breakdown of the resin throughout the matrix.

 

 

 

● CONCRETE – FULL INSTALL
Application to a new permeable concrete surface:

If the concrete base is to be laid as part of the resin bound groundworks then the specifications listed in the ‘substrate specifications’ section of this document should be consulted. No concrete base should ever be less than 50mm in depth (foot-traffic), the concrete should always be permeable, comply with BS5328 and be given a minimum of 7 days to cure before the application of the resin bound surface.

 

IMPORTANT: As with tarmacadam, it is desirable to keep the time between the concrete base being installed and the surface layer (such as resin bound) being applied to it as short as possible however, not allowing a sufficient cure time can result in system failure. Not unlike the resin used for a bound surface, concrete has different stages of curing. The types of concrete typically used for a domestic driveway will achieve approximately 50% of their strength after 24 hours. Between 80% and 90% of the concrete’s total strength is usually achieved after three days. After seven days the concrete should have cured to over 95% of its total strength with full strength/cure taking up to 12 months.

The reaction process that cures cement is called Hydration and this involves the cement reacting with water to form calcium silicate hydrate compounds. As the cement reaction is taking place the level of water left in the concrete is constantly reducing. If water is still present in the concrete when a resin bound surface is applied to it, the isocyanate (hardener) will begin to draw the remaining moisture out of the cement and use this as part of its own curing reaction. The overall strength of a resin bound surface applied to a three-day old concrete surface can be reduced by 20% when compared to a resin bound surface laid onto a seven-day old concrete surface.

 

 

 

● COMPACTED DTp3 / MOT TYPE 3 – FULL INSTALL
Application to a new compacted DTp3/MOT Type 3 surface:

The application of a resin bound surface onto a compacted, DTp3/MOT Type 3 base should only be considered if the completed installation area will not be subjected to any forms of vehicular traffic or heavy loads (such as garden paths and tree-pits).  A resin bound surface laid directly onto a compacted base should be a minimum depth of 25mm and will be suitable for foot-traffic only.