Permeable concrete (or "pervious concrete" in North America) is used to reduce local flooding in urban areas and is an important sustainable urban drainage system. However, permeable concrete exhibits reduction in permeability due to clogging by particulates, which severely limits service life. This paper reviews the clogging mechanism and current mitigating strategies in order to inform future research needs. The pore structure of permeable concrete and characteristics of flowing particulates influence clogging, which occurs when particles build-up and block connected porosity. Permeable concrete requires regular maintenance by vacuum sweeping and pressure washing, but the effectiveness and viability of these methods is questionable. The potential for clogging is related to the tortuosity of the connected porosity, with greater tortuosity resulting in increased potential for clogging. Research is required to develop permeable concrete that can be poured on-site, which produces a pore structure with significantly reduced tortuosity.

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Permeable pavement is utilised in order to alleviate flooding in towns, cities and other urban areas, but it is prone to clogging, has relatively low strength and requires regular maintenance. We have developed a novel permeable pavement with low tortuosity pore structure that can be cast on-site that is not only resistant to clogging, but also has high permeability and strength. This high strength clogging resistant permeable pavement (CRP) was prepared by introducing straight pore channels of varying size and number into self-compacting mortar. Samples with porosity ranging from 2 to 32% were tested. In all cases, permeability and compressive strength were substantially higher than conventional permeable concrete. More significantly, CRP can be engineered with low porosity (5%), high strength (> 50 MPa) and high permeability (> 2 cm/s), but does not clog despite extensive cyclic exposure to flow containing sand and clay. A simple method to model the permeability of CRP from the pore structure is described. We report for the first time a high strength clogging resistant permeable pavement capable of retaining sufficient porosity and permeability for storm-water infiltration without requiring frequent maintenance. This innovative system will help alleviate urban flooding and contribute towards a more sustainable urbanisation.

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Permeable concrete pavements are becoming more common as a stormwater management system to mitigate urban flooding. However, they have a number of well-defined drawbacks including low permeability, high clogging potential, and low strength and durability, notably in cold climates exposed to freezing and thawing. A new generation of high-strength clogging resistant permeable pavement replacement (CRP) has been developed, through extensive laboratory work, to address these shortcomings and advance the field of permeable pavements. This paper reports on new advances in permeable pavement systems and the performance of a range of conventional permeable concrete and the developed novel CRP of varying porosity exposed to freeze-thaw cycles. This will allow performance evaluations of both systems in a cold climate. The tests involved exposing samples to temperature varying from -20 o C to +20 o C and measuring changes in mass, area, compressive strength and ultrasonic pulse velocity after each cycle. These new results show that CRP is highly resistant to degradation caused by freeze-thaw cycles compared to conventional permeable concrete, reducing maintenance requirements and improving service-life. This study presents the first high strength clogging resistant permeable pavement replacement that is durable under frost action, these findings will support and enable wider use of permeable pavements in cold regions.

Permeable concrete pavements are one of the most promising mitigation strategies used to prevent surface flooding. Alalea Kia of Imperial College London introduces a robust new design which is ten times more permeable than conventional systems and resistant to clogging.

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