About 5% of the active RMX aggregate quarries in the UK have certified active ecological management plans in operation and would be acknowledged as such by GQCF.
These sites can be found in the linked document on the following Biodiversity Benchmark Certification web site.
A number of the leading RMX suppliers also publish case studies of exemplar projects that demonstrate the art of the possible from the perspective of delivering Biodiversity Management:
Once Quarries are decommissioned there are tremendous opportunities for their restoration in support of wildlife. The Mineral Products Association maintains a database of publically assessable restored quarries which it designates as a National Nature Park.
The MPA also run bi-annual Quarry and Nature award program.
The Wildlife Trusts also manage a number of restored quarries which are open to the Public and which can be found on this web site.
The RSPB have been running their Nature After Minerals Project with partners including the Minerals Products Association since 2006 and some case studies from the scheme can be found here:
The British Aggregates Association also highlights a number of quarry restorations, as can be found here
While RMX aggregate only accounts for 20% of the quarried aggregate in the UK, its use within 2 hrs of production means that quarries have to be located throughout the UK to support RMX supply. About 5% of RMX aggregate quarries have certified active ecological enhancement plans in operation. This means that a majority of quarries still need to be verified before the supply chain will be in a position to specify affordable Green Quarry Concrete without a price or carbon premium. There are two types of quarry: Crushed rock and Gravel. Specification of RMX means that there is little opportunity to substitute recycled aggregates within optimum carbon RMX production. There are exemplar ecologically enhanced operational sites and many disused quarries that have been restored to become nature reserves open to the public.
Ecological Challenges and Successes
Ecological Challenges associated with the supply of Ready Mix Concrete aggregate
Ecological Successes
GB has a ‘rock line’ which extends roughly from Weymouth in the South-West to Kingston-upon-Hull in the North-East. To the north of the rock line, particularly in Scotland, Wales and north England, there are large natural deposits of rocks of the type that can be accessed for extraction and crushing. By contrast, to the south of this line, particularly in East Anglia and the South-East, naturally occurring deposits of sand and gravel are abundant but there is little or no accessible rock. Some exceptions to this exist, for example there are large deposits of granite in Leicestershire.
For the manufacture of RMX (which accounts for about 20 per cent of aggregates used in GB), the main `aggregates used are sand and gravel (60 to 65 per cent) and crushed rock (25 to 30 per cent). For specification purposes use of recycled and secondary aggregates is low (5 to 15 per cent).
Rock quarries usually operate for at least 30 years and are developed in distinct 'benches' or steps. A controlled explosion is normally used to release the rock from the working face. It is then transported by truck or conveyor to a crusher to go through a series of crushing and screening stages to produce a range of final sizes to suit customers'
needs.
Sand and gravel quarries are much shallower than rock quarries and are usually worked and restored in progressive phases. This means the area exposed for quarrying at any time can be minimised and land that has been 'borrowed' is out of productive use for a limited period.
Use of Recycled Aggregate in RMX
Generally it is desirable to reduce the amount of quarrying so as to reduce the ecological impact of this activity. Increasing the use of recycled aggregate or substitute aggregate is fundamental to this objective and this was part of the motivation for the introduction of the (quarried) Aggregate Levy. However, of all the uses of quarried aggregate RMX has the highest engineering specifications which for the main part will continue to require the use of virgin quarried aggregate. Where recycled aggregate is used, cement content has to be increased which has carbon implications. This explains why the use of recycled aggregate in RMX at 10-15% is so low. RMX aggregate represents about 20% of all the aggregate quarried in the UK.
Ready Mixed Concrete (RMX) is concrete that is produced in a freshly mixed and unhardened state. RMX is manufactured by mixing highly specific quantities of cement and (if desired) other cementitious products with fine aggregates and coarse aggregates, water and other additives. The specific composition (and resulting properties) of RMX can be customized to suit different applications. RMX must be used within 1 to 2 hours of being produced, there is broad consensus that the markets are local (catchment areas are typically within about 8 to 10 miles of RMX plants.
This localisation between production and use of RMX drives the number of UK quarry sites. This means that before cost effective 'Green Quarry Concrete' can be specified within standard construction industry procurement processes, a majority of the 450 or so UK quarry sites have to have been independently certified as having operational biodiversity enhancement plans. Generating the funding to enable this initial transition is the first objective of the Green Quarry Concrete Fund (suggested wording for use with in procurement specifications is available from the GQCF).