Resin Bound Knowledge Base
Resin Bound Knowledge Base
Materials - Coverage Rates
The coverage rate of any resin bound system is not a set figure. It varies due to the fact that the aggregates used are sold by weight but have a different density (i.e. a tonne of feathers will cover a much greater area than a tonne of lead). This is immediately apparent as many of the forced action mixers commonly used in the resin bound industry (such as the Baron E120) have a mixing capacity of 90 litres and yet can hold in excess of 100kg of aggregate without overflowing.
If a set coverage rate is used for a 100kg mix of different aggregates this causes one of two problems:
1. If applied at a constant accurate depth, the installation will be short of material or have an excess of material upon completion.
2. If applied by area (mix markers) each marked area will contain a 100kg mix however the application depth will either be less or greater than the required depth.
The second issue is the most common as typical installations are laid by marking out areas for each mix. The installer may then assume that the desired, constant depth is being achieved but this is not the case. The density variation of aggregates can be far greater than expected as this example highlights:
● A 100kg mix using an aggregate with a specific gravity of 1.64 (61.1) (Kendal Gold) will cover 3.1m² when laid at a depth of 20mm.
● A 100kg mix using an aggregate with a specific gravity of 1.29 (77.6) (Farnham Flint) will cover 3.9m² when laid at a depth of 20mm.
● On a surface area of just 100m² this would be a difference of 7 x 100kg mixes (kits) or result in an average application depth difference of 4mm (16mm depth instead of the required 20mm)
Due to typical installation methods the variation of coverage caused by aggregate density is lost in a change to the application depth which in the most extreme cases (the highest density aggregate and lowest density aggregate) can be over 4mm of the average. It is more likely to be as little as 1mm or 2mm using the most common aggregate selections however for an application at 15mm depth using a 3mm to 5mm stone this can result in the average matrix depth failing to achieve the 3x5mm (three times the largest stone) absolute minimum requirement. This can also have the reverse effect and increase the average application depth and overall cost of an application due to an increased average application depth. This is not usually the fault of the installation team as they stick to applying each 100kg mix to the coverage area specified by the supplier.
This table details the specific coverage rates of each 100kg StarScape ULTRA mix. The m² area should be the size of the area marked out for each mix:
In order to ensure the correct minimum application depth is maintained and the ordered material is sufficient for the total area it is good practice to mark out areas for each individual mix using chalk or a spray-on line marker. These can then be numbered to reflect the desired application order
This calculator can be used to work out exactly how much StarScape ULTRA Resin and decorative aggregate is required for a specific application depth and area:
Simply select the desired aggregate blend name, application depth (mm) and area (m²) to calculate the material requirements.
A full list of the aggregate blends can be viewed here:
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