Monday, November 9, 2009

New asphalt able to absorb water is being tested in Sao Paulo

New asphalt pavement financed by the city council begins to be tested at USP (University of Sao Paulo); solution can be used in 60 trouble spots of the city.

This week, a new type of asphalt — that can absorb large volumes of rainwater in a few seconds —, begins to be tested.

If the material proves an effective solution during the summer season — when the capital becomes the target of frequent storms —, it will be used by the city to combat the chronic flooding points.

Funded by the SIURB (Municipal Urban Infrastructure), the project, budgeted at R$ 400 thousand, is being developed since July by the Fundação Centro Tecnológico de Hidráulica (Foundation of Hydraulic Technology Center).

According to the hydraulic engineer Alfonso Virgilii of SIURB, permeable asphalt can absorb up to 1 liter of water in 26 seconds. "It absorbs the volume of a rainstorm that generates 39.5 mm of water just in one hour." The absorption capacity is due to the porosity of the material and the use of stones in the asphalt, which retain water. "Then a small reservoir causes the retained water to seep slowly into drains and streams, avoiding overflows." He estimates that the technology could be used in up to 60 outbreaks of flooding the city, especially on secondary roads. The cost is R$ 230 per m², compared with R$ 195 spent on the common asphalt.

The new surface also increases the braking power of the vehicles during rain due to the pores.
Moreover, the emission of noise from tires is reduced by about three decibels.
[source: destak]

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