Epoxy resin-bound gravel - review

Landscape and Garden Product Directory

The distinction between plastics and resins is 'arbitrary' (Encyclopedia Britanica). They are polymers, which are very long-chain molecules. It is the great length of the chains which produces their characteristic flexibility and ability to soften when heated (hence the name 'thermoplastic'). Natural resins, containing cellulose, are exuded from coniferous trees and have a delightful aroma. Artificial resins use oil as a feedstock.An epoxy resin is is a polymer with oxygen and carbon atoms in the ratio 1:2 bonded into long chains. Epoxy derives from epi-, above and oxygen. Epoxy resins are used in paints, glues and bonding agents. Epoxy resins set hard when two components are mixed. They can be clear or have an amber or brown colour. Epoxy resins are highly durable and have great adhesive strength.Weeds do no grow through resin bound paving.

Given the above properties, resin is superior to bitumen as a binding agent for paving: you see the natural colour of the gravel aggregate instead of the sticky blackness of bitumen. The disadvantage is that resin is much more expensive than bitumen. It has therefore become common practice to lay a base of bitumen-bound paving and surface it with a thin layer (4-8mm) of resin-bound gravel. To produce a thin layer, and save money on the resin, small-size gravel aggregate is used. The resultant paving is much pleasanter than bitumen paving - but very much more expensive than unbound gravel paving.

Permeability to water is another issue. From a sustainability standpoint, it is much better if a paving surface is permeable. The water can then trickle back to replenish underground water supplies, instead of flowing into drains and causing downstream flooding. From this point of view, two different types of resin-bound gravel should be distinguished:

  • If a layer of resin is applied to an impermeable base course, then the resin-bonded gravel will also be impermeable. to water.
  • If a pre-manfactured resin-gravel compound is used, the pavement can be permeable if laid on a permeable concrete or macadam base.
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Comments

  • about 1 year ago Daren Chambers said

    Hi, You make reference to epoxies for resin bonded and resin bound systems. Although epoxies are used it needs to be stated that epoxies are the low end of the market, epoxy bonded is highway surfacing used for cheap resurfacing; appearance is not the first priority against specialist PU resin bonded products. Epoxies are not representative of the specialist end of this market.
    In bound trowel systems PUs have greater performance and longevity and importantly provide UV stable performance for bound systems which unfortunately a lot of cheap driveway companies neglect to say or advertise and the performance is short term compared to PUs.
    All top companies use PUs only that are UV stable. The cheap driveway companies buy on price over quality. A headache for the longevity of the resin bound market creating bad press. Resin bounded is a thin layer of a few mm as a scatter system - the strength is in the bauxites used. Thickness is dependent on size of aggregate. Resin Bound the porous, trowel system must be laid at a minimum of 15mm if using the top market leader up to to 18mm-24mm dependent on application from others. The strength is in the mix blends of aggregates and this need to be sourced from a recommended supplier of resin and aggregate that can provide actual slip resistant figures to back up the claim of slip resistance using a recognised test process like slip alert testing. It is always advised to ask if the manufacturer is ISO9001 and not a would be contractor buying cheap resins off the shelf formulating in a shed. They must be members of industry bodies like BALI and especially FerFa the resin associations of specialist resin suppliers. Also the use of recycled glass has limited use due to crush values. Be careful if considering. SUDS is good for the environment but also the environmental issue is the resins used. Quality resins can be considered environmentally friendly and test figures can be produced by a quality manufacturer. Importantly, only use the manufacturer Approved Contractors that have certificated proof as they are re-assessed every year for performance and quality. They will have a reference number you can check with the manufacturer. If a company is offering a long guarantee make sure they are an established company of 10 years plus that you can be re-assured will be around to honour any guarantee.

    Only resin bound is SUDS compliant - permeability is dependent on specification.

    Regards

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