Evaluation of an open-cell phenolic foam as a water barrier system for permeable pavement systems to control stormwater

Laburpena

Urbanisation, land development and climate change associated phenomena, such as flooding and droughts, lead to the need for more effective stormwater management. Permeable Pavement Systems as a Sustainable Drainage source control measure have the ability to control stormwater and improve the water quality. Although PPS is a promising alternative to conventional pavements, variability on the weather conditions around the world, geomorphologies and type of pollutants make their wider implementation challenging resulting to either under or over engineered solutions. Further research is required to understand the mechanisms under which water retention and attenuation are achieved in PPS and the influence of water barrier systems. In view of this issue, this project evaluated the potential of an opencell phenolic foam as a water barrier system in PPS. OASIS Floral Foam as a highly absorbing material was evaluated for its ability to enhance or even replace conventional geotextiles in PPS. Due to the novelty of the proposed non-conventional application of the phenolic foam in pavements, the water storage capacity, absorption rate and drying rate of the material were investigated following with investigation of the hydraulic response of PPS utilising OASIS Floral Foam as a barrier system in comparison with PPS utilising an upper Inbitex geotextile. The water storage capacity of OASIS Floral Foam was found to be 25L/m2 for a 2.5cm thickness, implying a 100% ability to fill its volume with water. Both OASIS Floral Foam and Inbitex geotextile found to improve the water retention and attenuation of PPS in comparison to unlined “conventional” PPS systems under laboratory simulated rainfall events. OASIS Floral Foam PPS found to respond better under low intensity consecutive rain events retaining and attenuating larger cumulative water volume than PPS with Inbitex geotextile, and performed better in every scenario before reaching its saturation point, after which the foam was acting as a filtration device and after which Inbitex geotextile was found superior. The influence of the phenolic foam on the structural integrity of the pavement and the effect of compaction on its water holding capacity were investigated by performing compaction tests on PPS like designs containing OASIS Floral Foam with various placement configurations, placement depths and sizes. Placement of the foam as a layer between aggregate beds found to significantly decrease the structural strength of the test rigs and reduced the foam’s water holding capacity up to 50%. On the other hand, placement of the foam as an infill in the aggregate bed minimised the effect on the structural integrity of the test rigs and resulted in 8% decrease on the water holding capacity of the foam for the best-case scenario. The placement configuration of OASIS Floral Foam in PPS designs found to have an influence on the hydraulic response of PPS, with layer placement presenting a 6% higher cumulative water retention in comparison to infill placement when responding to the laboratory simulated rain events.