The use of commercially produced Carbon-Negative aggregates from Carbon8 (a British company which applies patented Accelerated Carbonation Technology (ACT) to solidify waste residues producing useful eco-friendly aggregates) is being investigated in the Caribbean islands of Trinidad, Tobago and St. Lucia. Typical construction of the subbase layer of pavements in the Caribbean include layers of virgin aggregate material (gravel, pea gravel) on which the base course layer is located. These materials are usually unbound granular (crushed stone, crushed slag, crushed concrete, slate) or cement-bound. Permeable Pavement Systems (PPS) have emerged over the years using various quality of subbase materials including large pieces of rocks and concrete. For the first time in the Caribbean, the design, construction and implementation of such pavement systems is being carried out. The novel pavement systems consist of permeable or pervious concrete paving blocks and the Carbon-Negative aggregates in the sub-base as an innovative and effective method of providing structural pavements, whilst allowing urban stormwater runoff to infiltrate naturally into the pavements (mimicking the hydrologic cycle) into the base/sub-base reservoir for urban runoff attenuation and an overall reduction in stormwater discharge. These pavement systems are being considered to reduce the overall carbon footprint on the construction and implementation phase of pavements, in addition to reducing surface water flooding in several towns and cities across these Caribbean Small Island Developing States (SIDS). The project includes ongoing experimental assessment of the Permeable Pavement Systems (PPS) using Carbon-Negative aggregates versus conventional pervious pavements from a water quality, structural integrity and hydraulic perspective. Stormwater is being collected from various towns and cities across the islands and applied uniformly over the pilot scaled permeable pavements using a rainfall simulator. The permeable pavements stormwater treatment efficacies are being evaluated for the removal and retention of nutrients (total nitrogen and total phosphorus), heavy metals (zinc, lead, copper, cadmium), suspended solids and turbidity. The hydraulic performance, flow through and clogging patterns of these pavements are also being measured over a simulated 10-year period of sediment loading. Load bearing and deflection test are being carried out on the various pavement designs to assess its structural integrity and load bearing capacity. Static and dynamic loads applied representing the maximum contact pressure varying from 0.03 to 1.7 MPa over the cross-sectional area of 0.2 m2 (permeable pavement surface area). These contract pressures represent various loads from heavy vehicles, cars, pallets and handling equipment of industrial areas (ports)
