Geo fill® is made by pelletizing fly ash. By adding a controlled amount of water in specially designed dish pelletizing pans, rounded pellets are formed. The pellets are then heated on a sinter strand to a temperature of around 1100°C. The result is a hard, honeycombed structure of interconnecting voids within the aggregate. The particles formed are rounded in shape and range in size from 14 mm down to fines; these are processed to the required grading, depending on the final use. Being a wholly manufactured aggregate, made from a waste stream, means that the quantity of fly ash being tipped is reduced and virgin aggregate extraction is reduced.
Geo fill® should be considered for use as an alternative to ‘normal’ weight aggregates in series 500 and 600 of the Specification for Highway Works.
- Bulk Fill: Geo fill® can be used as a bulk fill material either bonded with cement or unbonded. Densities are typically 700–900 kg/m³, depending upon the ambient moisture content, which reduces the dead load and lateral pressure. Due to the spherical shape of the aggregate, minimal compaction is required.
- Drainage media: The particle size and shape of Geo fill® gives it excellent hydraulic conductivity properties. It can be shown that up to six times more water will pass through the aggregate than standard gravel aggregates, reducing the risk of silt blockages in trench systems. Finely graded lightweight aggregate can be used allowing grass to grow and ‘knit’ over the trench in a few days.
- Arrestor beds: Geo fill® is used in arrestor beds to bring run-away vehicles to a halt in a controlled manner. Risk of injury and damage to vehicles is minimized. The aggregate does not degrade or compact over time, keeping it effective with the minimum of maintenance.
- Pipe bedding: Geo fill® is used as a granular bedding and sidefill for rigid and flexible pipes. BS EN 1610 – Construction and testing of drains and sewers details the design requirements.
Geo fill® will reduce pressures on both foundations and structures due to being approximately 50% of the weight of ‘normal’ aggregate, whereby savings in the design can be made.
Consult manufacturer's literature for further details relating to physical and chemical properties.