The stones are excavated from gravel pits predominantly in the UK, but also from around the world. It arrives in 20-75mm pieces and is then screened to 1-3mm, 2-5mm, 3-6mm, washed, kiln dried and then bagged after drying. These bags are then stored in a temperature-controlled environment to prevent condensation; if any bags develop condensate, then they will be unusable due to the water-based polyurethane resin as this will create weakness within the structural integrity of the material and discolouration. The stones are all-natural colours, not manmade hence why they do not discolour.
The resin is UV polyurethane which is water-based, giving it the extra strength and flexibility that other types of resin do not possess. This type of resin is mainly used on the hull of ships due to the strength and flexibility but is chemically adjusted to bind with the stone as well as any other type of material to be bonded. The correct resin should be brought for the appropriate application.
As the resin is clear we can use different coloured stone unlike other products, i.e. concrete is mixed with stone grit and cement, and due to the cement (binder) being grey, the overall finish is grey. Tarmac is stone and bitumen, as the bitumen is black, the finish is black. There are two types of resin-bound binder; one is standard of which over a 2-week period discolours to a yellow and even green colour on certain whites and silvers.
There is an optimum mix of resin and stone necessary to achieve a 25-year surface (if installed correctly). The mix consists of 50kg of 2-5mm stone, 50kg of 1-3mm stone, 5kg of fine sand and 7.5kg of resin; this will then create a solid, dense surface. This is laid at a 20mm thickness and once trowelled is compressed to 18mm. At 15mm our resin mix will take 30 tonnes before breaking, so the base must be good, as Civil engineers we recommend 100mm of permeable concrete for structural integrity on the domestic driveway, this is the only base to be used to achieve a 25 year resin surface. Tarmac is not a 25 year product and needs replacing every 5 years to retain its 25 year structural base integrity, as we all know the forever replacing of tarmac along our roads and foot paths.
The resin mixture is not to be laid in the rain as can cause discolouration and weakness within the new surface .