FAQ's

PERMASTONES: Piove® | Percola®

Q. What is the tensile splitting strength of the pavior?
A. The pavior exceeds the minimum in accordance to the BS EN 1338:2003 6.3.8.3 of 3.6 N/mm² (MPa)

Q. Is there a technical drawing available of the pavior?
A. The technical drawing is available as a CAD file in both DXF and DWG formats Downloads Percola Technical Drawing (DWG) or (DXF)

Q. What technical specification does Percola comply with?
A. BS EN 1338:2003 Concrete Paving Blocks, in addition the product complies with PTV 122 permeability rating a European guideline for that is included in EN 1338.

Q. How is storm return expressed?
A. Storm return was often expressed in number of years as a once-in-so-many years storm event. It is now normally calculated as the capacity to absorb rain water in litres/second/hectare.

Q. What is the storm return?
A. The Percola® drip-holes represent a minimum of 10% of the surface area and provide an area in excess of 0.025m²/m² when filled with suitable aggregate. Flow rates of up to 4000 litres/sec/hectare (4x10-4 m²/second) are achievable compared to typical flows for UK rainfall of 180 litres/sec/hectare.

Q. What is the requirement for the aggregate used in the drip-holes?
A. The aggregate required to maintain the water-permeability that is used to fill up the drip-holes needs to have a water-permeability of 5.4x10-4 m²/second and is typically an Igneous stone such as Granite or Basalt.