Porous tarmac system: TarmacDry frequently asked questions

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Listed below is a selection of questions and answers that will hopefully answer the key questions you might have.

Q. Who can install TarmacDry porous asphalt system?

TarmacDry is installed by Tarmac National Contracting using conventional paving equipment. We offer an integrated package for TarmacDry, depending on your requirements, which includes:

• Design
• Service 
• Hydraulic design 
• Value engineering 
• Early contract involvement 
• Build 
• Cleaning and maintenance
• Warranty and after care service

The permeable asphalt system comes with the full backing of the British Board of Agrement (BBA). See more TarmacDry benefits.

Q. Is cleaning or maintenance part of the contract?

This can be purchased as an aftercare service. See more in Cleaning and maintenance.

Q. Can TarmacDry be manufactured with recycled materials?

Yes, both the granular and asphalt layers can use recycled materials, such as rail ballast. This helps to meet sustainability targets. See more in TarmacDry, BREEAM and sustainability.

Q. Can TarmacDry harvest captured rainfall?

Yes, the water in the system can be harvested for re-use. Current studies show the quality to be suitable for use as grey water. See more in TarmacDry benefits.

Q. How much water can be stored in the reservoir layer?

For trafficked areas, TarmacDry provides a minimum water storage of 60 litres per square metre. There is no maximum limit to the water that can be stored in the system. We will design the system around the projects’ requirements.

Q. How do we determine the thickness of the TarmacDry porous asphalt pavement?

There is a minimum thickness required to deliver structural performance of the pavement. Layer thickness will vary depending on application, traffic loading and water storage capacity.

Q. Could a conventional surface course be used on running lanes, turning areas and driveways?

Yes, the falls could be set so that the water flows off to the sides onto adjacent TarmacDry surfaces. So a combination of traditional asphalt areas with TarmacDry can be used.

Q. What the minimum quantity of TarmacDry that can be specified?

The minimum quantity of TarmacDry we would supply is 500m2.

Q. Is it ok to use grit salts on the TarmacDry system?

If required, traditional rock salt conforming to BS 3247 Fine Grade 6.3mm (as used on the highway) can be lightly spread to prevent the formation of frost and ice. The BS specification for this material requires less than 7.5% insolubles. We would not, however, recommend a continuous and heavy spread rate over a prolonged period of time.

For any other questions please email tarmacdry@tarmac.co.uk.

Q. Do you supply TarmacDry outside of the UK?

Currently we do not have any asphalt plants outside the UK.  This means that we can supply TarmacDry to locations based in England, Scotland, Wales and Northern Ireland.

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