There are a number of porous surfacing types and techniques that FGSL are able to offer, these include:
Open-textured soil or granular material
These are gravel or similar surface on a sub-base. Typically used in locations where low volumes of light weight traffic, such as cars, will be present and a low cost solution is required. There is little design and the use is restricted to locations such as pedestrian areas, driveways on private property and temporary car parks.
Geo-synthetic gravel/grass protection systems
These are modular interlocking plastic paving systems, which are in-filled with gravel/grass/aggregate and bedded on a free-draining structural sub-base layer. Typically used for light/medium loadings such as car parks or locations where occasional heavy vehicular loadings occur (i.e. refuse collection vehicle, removal Lorries, etc.)
Small porous elemental surfacing blocks
Precast blocks formed of low-fines concrete or other materials, which results in the blocks having many small, interlinked internal voids throughout their section. These are laid on a recommended sub-base which has in the past varied from Type 1 sub-base (which is actually relatively impermeable) to clean gravel and crushed rock, or other open-textured support. Typical uses are for public, engineered surfaces carrying light loading but of high frequency such as shopping centre car parks.
Continuous laid porous materials
Porous asphalt, porous concrete or resign bound aggregate, laid on a recommended sub-base of free draining granular material. Remains free-draining provided regular surface maintenance limits the deposit of debris in the surface void spaces. Typical uses are for public, engineered surfaces carrying high volumes of heavy and or light loading, such as shopping centre car parks and service roads.
Large elemental surfacing blocks
Precast concrete blocks with a pattern of voids intended for filling with soil, which allow or the growth of grass (grass concrete), laid on a recommended sub-base. These may remain relatively free-draining provided trafficking does not compact the earth fill within the void spaces. Typical uses are for low cost, temporary or occasional usage roadways and parking areas where vehicular loading is generally light and where the appearance of a grassed surface is seen as environmentally desirable, such as car parks and fire access routes.
Small elemental surfacing blocks
Precast concrete blocks with a pattern of indentations along their edges intended to be filled with sharp sand/gravel, laid on a recommended sub-base, which should be single size crushed rock or other open-textured support. This remains free-draining provided surface maintenance limits the deposit of debris in the indentations and joints between blocks. Typical uses are for office and shopping centre car parks.
Continuous-laid permeable material
In-situ cast concrete systems are available that provide a surface with large voids for infiltration, whilst offering hard standing for vehicles. The surface is unsuitable for small-wheeled trolleys and pedestrian use over large areas and has limitations aesthetically. Typically used in car parking areas.