A permeable pavement system utilising recycled concrete aggregate in the sub-base - Preliminary laboratory performance assessments

Sustainable development gears towards preserving the environment and conserving the rapidly diminishing natural resources such as natural resources. This research seeks to assess the performance of crushed recycled concrete aggregates (RCA) from Trinidad and Tobago as sub-base materials in permeable pavement systems (PPS) applicable to urban stormwater management systems across the Caribbean small island developing states (SIDS). Presently, research is lacking regarding the performance of RCA in PPS. These pavement systems are being considered as a natural resource conservation attempt, in addition to reducing surface water flooding in several towns and cities across these SIDS. The project includes laboratory experimental assessment of PPS using RCA versus virgin aggregates (limestone from Trinidad and Tobago and basalt from St. Lucia) from a stormwater quality, geotechnical and hydrologic viewpoint. Stormwater is being collected from various towns and cities across the islands and applied uniformly over the pilot scaled permeable pavements using a purpose-built rainfall simulator. The permeable pavements stormwater treatment efficiencies are being evaluated for the removal and retention of nutrients (nitrates and phosphates), heavy metals (zinc, lead, copper, iron and manganese), suspended solids and turbidity. Hydrologic performances are also being assessed through numerous simulated storm events at various intensities. All pavements have handled 15-minute high intensity rainfall inputs (in excess of 222 mm/h) with 100% infiltration (no surface runoff) recorded. In terms of total suspended solids (TSS) removal, results showed that removal efficiencies varied from 31 to 85% with the RCA test rig recording the highest average TSS trapping efficiency of 58%. The test pavement with RCA in the subbase has performed similarly or better than those with virgin aggregates.