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Maintenance Equipment Testing on Accelerated Clogged Permeable Interlocking Concrete Pavements


Permeable interlocking concrete pavements (PICP) allow stormwater to infiltrate directly through aggregate-filled joints. The lack of proven, cost-effective, practical approaches for permeability restoration prevents the wide-spread adoption of PICP systems in Canada (and North America).

The University of Toronto conducted a study at a PICP test pad, constructed in 2017, located at the Toronto and Region Conservation Authority’s (TRCA) Kortright Centre for Conservation in Vaughan, Ontario. The test pad included seven 3 m by 3 m (10 ft by 10 ft) PICP cells constructed with a generic grey concrete paver arranged in a herringbone pattern.

Five test cells were clogged with street sweepings graded to match clogging sediments sampled from mature PICP parking lots within the Greater Toronto Area. The test cells we clogged over several weeks over the summer in 2017 through a controlled accelerated clogging procedure developed by UofT researchers. Surface infiltration capacity was measured following ASTM C1781 procedures, and restorative maintenance was considered required when mean surface infiltration measurements approached 250 mm/hr (10 in/hr). Subsequently, each cell received restorative maintenance. Five different maintenance treatments were tested including a high pressurized-air and vacuum system, regenerative air street sweeping, power washing followed by vacuuming, vacuum street sweeping and waterless mechanical street sweeping.

The sixth test cell was clogged with a mixture of street sweeping and clayey soils and maintained with the high pressurized-air and vacuum system to explore the impact that cohesive sediments have on maintenance effectiveness. Finally, the seventh test cell was treated with early and repeated maintenance with a regenerative air street sweeper.

Study Findings
The results of this study demonstrate that all maintenance techniques significantly restore the pavement’s surface infiltration capacity. Under some conditions, high pressurized-air and vacuum systems as well as vacuum street sweepers can restore surface infiltration to its original post construction condition. Key findings of this research include the following:

Restorative Maintenance – the research was able to rate each technique used and determine the level of performance that was recovered.
Joint Penetration Depth – Joint penetration depth was a strong indicator of overall maintenance effectiveness.
Cohesive Soils – significantly decreased the effectiveness of restorative maintenance.
Early and Repeated Maintenance – applied maintenance was more effective when conducted repeatedly and earlier.

Conference Paper Details

Session title:
Innovations in Pavement Management, Engineering and Technologies
Drake, Jennifer
Scott, Jody