Rubber Aggregate paving – the SuDS and environmentally friendly option
If you have watched the news at any time since Christmas, you will probably, and in some cases painfully, be aware of the impact of persistent inclement weather. Quite simply, climate change, population growth and urbanisation are all driving an increasing tendency for extensive flooding.
The Environment Agency, local and national Government are well aware of the issue and are actively implementing policies and guidance to try and curtail the risk, including much tighter control of planning and building regulations.
One key focus area is the provision of sustainable drainage systems (SuDS) which are realistic and viable alternatives to the direct channelling of surface water through networks of pipes and sewers to nearby watercourses.
SuDS solutions mimic natural drainage by allowing water to be absorbed over a wider area directly into the ground. This infiltration improves water quality, allows more natural management of the underlining water table and substantially reduces flow rates to watercourses.
Over recent years, a number of SUDS compliant surfacing solutions have been developed that offer enhanced permeability to better allow natural infiltration, and one of the most exciting is rubber aggregate surfacing.
This product uses end of life tyres (or other end of life rubber products) in granular form, together with natural aggregates and polyurethane binder, to deliver environmentally friendly high performance surfacing.
One such rubber aggregate product, CONICA’s CONIPAVE RA, uses large rubber granules and aggregates to create a highly permeable, flexible and decorative solution.
There are no direct test standards applicable to SuDS solutions, so CONICA has tested the CONIPAVE RA system to the widely recognised BS EN14877 standard for sports surfaces. The water infiltration test within the standard (BS EN 12616 method) requires a result of ≥ 150mm/h. Passing the test is required to ensure that the surface will provide year round puddle free performance. The average result for CONIPAVE RA was over 17,000 mm/h or in excess of 113 times better than that required by the standard proving the system offers outstanding permeability.
Clearly the surfacing itself is only part of the picture. To optimise permeability, it is essential that any sub base is also permeable. Therefore, most rubber aggregate surfacing solutions need to be installed over a minimum of 100mm of MOT type 1 compacted stone to be classed as a SuDS complaint solution. The use of a 100mm layer of MOT type 1 compacted stone often requires some basic earthworks which will also help alleviate any surface compaction which can negatively impact permeability.
Rubber aggregate surfacing offers a number of other benefits which also makes it a popular choice over more traditional asphalt and concrete surfacing.
Firstly, the polyurethane binder used will be flexible, as is the rubber. Both, in combination, provide a surface that is resistant to cracking caused by the extremes of climatic conditions and substrate movement, including that created by tree roots. This benefit also makes rubber aggregate surfacing the ideal solution for tree pits.
The second major benefit is safety. Rubber aggregate surfacing typically offers excellent slip resistance (circa 55 PTV in wet conditions) and the flexible impact absorbing nature minimises the risk of injury resulting from a trip or fall. Accordingly, this type of surfacing is now being used for school daily mile activity tracks, surfacing around outdoor gyms and for trim/jogging trails. It is also a great solution for hard landscaping at healthcare and care/nursing home facilities.
The third major benefit is ease of installation. Once any earthworks have been completed and the sub base installed, all that is required to complete a high quality installation is a simple forced action mixer, a wheel barrow and some simple hand tools (i.e. there is no need for heavy machinery which is expensive to hire/use, difficult to transport to more remote locations and not environmentally friendly to use). This means that the product can easily be installed by specialist surfacing contractors, as well as landscaping teams, general works contractors and correctly trained council employees.
The product comprises of a single layer so is also very fast to install.
The fourth major benefit is that rubber aggregate surfacing is more visually attractive than asphalt or concrete paving. A wide range of aggregate colours are available and the rubber element can be either black, grey or both. These options provide much more design flexibility and can create surfacing that more readily complements the surrounding environment.
The final benefit is the cost effectiveness. Minimal earthworks, no specialist equipment, access to local labour and low cost materials all create a financial model whereby the overall installed cost is extremely competitive when compared with traditional paving solutions. Longer term, durability is excellent, there is very low risk of damage through climatic conditions and substrate movement, and any repairs can be simply and cost effectively completed in a manner that closely matches the surrounding area.
Whatever your paving need, be it a remote nature trail or urban path, rubber aggregate surfacing may just be the ideal solution.