Maintenance

For small areas of HydroSTON pavement, particularly in residential properties, eg footpaths and courtyards laid with HydroSTON 50 pavers, maintenance can be carried out manually by brooming, vacuum sweeping or machine blowing. In the case of hand brooming, a stiff bristle brush should be used.

Machine blowing should not be used on HydroSTON 80 pavements laid with joints as blowing may dislodge jointing aggregate and destabilise the pavement. Regular stiff bristle brooming is recommended for HydroSTON driveways.

Maintenance of larger trafficable areas where HydroSTON 80 pavers are installed can be carried out either manually with a stiff bristle broom or mechanically with street cleaning vehicles that perform sweeping and suction functions – eg The Green Machine range of outdoor sweeper machines or MacDonald Johnston compact sweepers (image right – courtesy Woollahra Council).

There appears to be no conclusive evidence as yet as to which type of sweeper is most effective for cleaning permeable pavements. The main types of sweepers are: mechanical broom machines; regenerative air sweepers; and pure vacuum sweepers (see article and retort on current sweeping best practices in World Sweeper 2010). An understanding of the mechanics of the different types of sweepers is required in order to assess potential effectiveness.

HydroSTON pavers are manufactured to the highest possible standards of quality using a carefully defined formulation of 5 mm crushed rock, sand and cement. The aggregate used in the manufacture of the supplied HydroSTON pavers is high grade virgin basalt. Under normal conditions and in line with most concrete products, HydroSTON pavers will continue to increase in strength over time.

Life expectancy of HydroSTON pavers is best expressed in terms of infiltration performance, which in turn is dependent on the maintenance regime applied. Cleaning of poorly maintained pavements can restore infiltration capacities to close to original capacities.

Since HydroSTON pavers are segmental, should any damage be caused to any paving units, the affected units can be easily lifted and replaced at very low cost. By contrast, replacement of traditional concrete or asphalt surfaces is often more difficult and costly.

Research indicates that infiltration performance is highly affected by the age of the pavement because of the entrapment of mineral and organic fines in the upper 20 mm of porous paving units. Borgwardt identified an overall trend in infiltration performance during the service life of a permeable pavement resulting in an exponential decrease of 75 to 90 % of the original infiltration rate. He therefore recommended that a runoff coefficient of 0.3 to 0.5 be adopted for permeable concrete block paving over the full service life compared with 0.8 for non-permeable concrete block pavements.

Borgwardt’s research was conducted in Germany under very different conditions than those experienced in Australia. Research being conducted into permeable pavements at the University of South Australia may provide greater information on the infiltration performance over time of porous paving. HydroCon was an industry partner in a successful application (LP110100222) for funding under the Australian Research Council’s Linkage Projects Grants Program (Linkage Projects Round 1 – 2011). Participants in the 3 year project are the University of South Australia (UNiSA), University of Adelaide, SA Water, City of Salisbury and Zero Waste SA. The project aims to develop new models for flow of stormwater through permeable pavements. The project is studying clogging and the impact of various cleaning techniques and aims to find optimal configurations for different materials and microstructures that enable more efficient design.