Aggregates provide the backbone of our world.
An end-product in their own right, aggregates are also a raw material used in the manufacture of other vital construction products such as ready-mixed concrete and concrete products, asphalt, lime and mortar, as well as in a wide variety of other materials such as fertilizer, tooth paste and glass.
Take away aggregates and our built environment would quite literally fall apart!
In a typical year, we need around 250 million tonnes of aggregates in the UK, of which 28% (c.70Mt) is derived from recycled or secondary materials with the balance coming from primary sources quarried from the land or dredged from the seabed. Collectively, this is equivalent to four tonnes for every man, woman and child. Around 90 per cent of all aggregates are used by the construction industry.
The main end-uses of aggregates are:
The UK's road network handles some 94 per cent of passenger travel and more than 60 per cent of freight. Aggregates feature at all levels of the road construction, from the concrete used in tunnels and bridges to the aggregates in foundation layers and the asphalt road surface (technically known as the “pavement”) which includes aggregates resistant to polishing, ensuring skid-resistance.
UK Railways need some three million tonnes of aggregates a year as track ballast.
The construction of a typical new house requires on average around 200 tonnes of aggregates and associated mineral products - from the foundations through to the roof tiles.
From your local schools and hospitals to major infrastructure like the Channel Tunnel - all are made possible by aggregates. In many cases they provide not just strength but, architectural beauty through special finishes.
Aggregates are needed to build and maintain our reservoirs and sewage treatment works. They have played a major role in the massive programme launched by water companies to overcome water shortages.
We are fortunate that primary aggregates are available in most parts of the UK so that local resources can be used in the main to satisfy local needs.
With the cost often doubling for each 30 miles travelled, aggregates are only transported long distances when, it is absolutely necessary.
The geological resources are not, however, distributed evenly and some geographical movement is necessary to balance the resources that are available in some parts of the country with the demands of the market elsewhere. The South East, for example, has its own supplies of sand and gravel, but relies heavily on the importation of crushed rock from the East Midlands and South West, largely by rail. While crushed rock produced from quarries in coastal locations may be transported larger distances by sea. A small proportion of aggregates with special properties, e.g. skid resistance for road surfacing, are only found in specific locations. These will be distributed more widely to meet local demands across the country.
Crushed rock is produced from three main rock types:
Solidified molten rocks (e.g. basalt, granite)
Formed by settlement of sediment particles (e.g. gritstones) or organic remains (e.g. limestone) in ancient seas
Created by igneous or sedimentary rocks being subject to heat or pressure (e.g. hornfels, quartzites)
Sand and gravel deposits are comprised of rock fragments eroded by the effects of being collected, transported and deposited by water or ice.
Sand and gravel deposits are generally shallow, sometimes only five or six metres thick, and quarrying operations are likely to be shorter term than for a rock quarry, with progressive restoration normally following closely behind extraction. Sand and gravel can also be dredged from licensed areas in coastal waters using purpose-built dredgers. See also the Marine Aggregates page.
The European Standards for aggregates were originally implemented on 1st January 2004 when the British Standards for Aggregates used in the construction sector such as BS 882, BS 1199/1200 and BS 63, were replaced with a new series of European Standards for Aggregates for use in concrete, mortar, asphalt, railway ballast and armourstone or used in their unbound and hydraulically bound forms. These standards are accompanied by their national guidance documents, the Published Documents (PDs), which interpret the requirements of the hENs as applied within the UK and are identified in the list below.
Whilst the aggregates have remained the same, the terminology, product descriptions, standard sieve sizes, grading presentation and test methods have changed with Type Testing, Factory Production Control (FPC) and CE Marking being introduced.
The information provided at that time can be downloaded from the documents listed below:
From the 1 July 2013 all construction products supplied in conformity with a harmonized European Standard, known as a hEN (this short term does not appear on the standards themselves), have to be CE marked before they can be legally placed on the market. Further details on the principles of CE marking are available here and in the 'Additional Information' documents at the bottom of this page.
The hENs, along with their national guidance documents, the Published Documents (PDs), which interpret the requirements of the hENs as applied within the UK, are identified in the list below and can be obtained from BSI at http://shop.bsigroup.com/.
All these European Standards are now nearing the end of their extended 5-year review and work is ongoing to not only revise and combine these Product Standards into a single Aggregates standard, but also on a Delegated Act of the European Parliament to allow inclusion of additional gradings and classes of characteristics (For further information please refer to the MPA Briefing note number 17 2017). The projected completion of this process and the publication of these standards is expected sometime in 2021. However, the publication of the new combined aggregate products standard may be delayed due European Commission review of the Construction Products Regulations.
The Aggregate Products standards published during 2013 were withdrawn under instruction from the European Commission due to some technical changes being made to some of the standards during the final editorial checking process. (For further information please refer to the MPA Briefing note number 17 2017).
The Evaluation of conformity of aggregates - Initial Type Testing and Factory Production Control is covered in the annexes of the current individual product standards.
The one standard which is not currently harmonized is BS EN 13285:2018 - 'Unbound Mixtures - Specifications'. Unbound mixtures, notably Type 1 and other granular sub-bases - Specification for Highway Works (SHW) 800 series, and imported fill materials - SHW 600 series are covered by this standard, and therefore cannot be CE marked. However, the aggregates used to produce the unbound mixtures which have to be in conformity with BS EN 13242 Aggregates for unbound and hydraulically bound materials for use in civil engineering work and road construction, do require CE marking. When an unbound mixture e.g. sub-base is supplied and information is required both on the aggregates used and for the mixture itself, the producer will generally supply a summary of the aggregate properties along with any specific test information for the mixture. BS EN 13285 should be published harmonized in line with the publication of the other Aggregate product standards, nevertheless due to similar issues to the Aggregate Product Standards BS EN 13285 will remain non-harmonized for the foreseeable future.
Guidance on the distributor's responsibilities under CPR, particularly in respect to the supply of bagged aggregates, can be found in a Construction Products Association (CPA) guidance document which can be downloaded below.
The UK left the European Union on 31 January 2020 and is currently in a transition period where the UK is no longer represented in the EU political institutions, but the rules and obligations of EU membership are still in effect. This will end on 31 December 2020. In the meantime, the UK government is negotiating for a trade agreement with the EU. BSI is working closely with the government to advise on the way standards are used to support regulations as well as on standards use within the trade negotiations through membership of the Strategic Trade Advisory Group.
The Ministry for Housing, Communities and Local Government (MHCLG) is currently updating guidance documents relating to placing goods on the market in the EU, GB and Northern Ireland which can be found via the links below:
The UK will adopt EU standards cited in the OJEU on 1st January 2021 as UK Designated Standards, the process for the adoption of revised standards cited in the OJEU is yet to be finalized.
The Mineral Products Association (MPA) is the trade association for the aggregates, asphalt, cement, concrete, dimension stone, lime, mortar and silica sand industries.