Reference should be made to the general notes
No composition requirements are given in The Structural Design of Heavy Duty Pavements for Ports and other Industries. However, the Specification for Highway Works provides limits on the content of glass, wood and impurities by mass for Hydraulically bound mixtures (HBM). Further details can be found in the Application Hydraulically bound base.
1. The limits for wood, glass and other impurities (Class X) have been set to encourage the use of processed recycled aggregates and aggregates from secondary sources. However, there are opportunities on many schemes to use mixtures with much higher proportions of secondary materials. If a particular source is available on or adjacent to the site it should be investigated as part of the site investigation. Where a possible source is known it can be tested to assess the construction and environmental risks associated with its use as part of the site investigation.
2. Higher limits are applicable if agreed with the Overseeing Organisation.
3. Clause 710 of the MCHW1 requires that recycled aggregates are produced in accordance with the ‘Quality Protocol for the production of aggregates from inert waste’ and the ‘Producers’ compliance checklist’ published by Waste and Resources Action Programme (WRAP). The results of all quality control checks carried out by the Contractor shall be compiled in accordance with the procedure set down in the above document and with those in Clause 710. These shall be delivered promptly to the client on request. For further information refer to the WRAP quality protocols for the production of aggregates from inert waste and the WRAP quality protocol checklists and guidance notes for producers, specifiers and purchasers of sustainable aggregates.
The particle size should be determined by sieving method of BS 812-103
|BS Sieve size (mm)|
CBM3 and CBM4
Percentage passing by mass
Nominal maximum size
0-8 (0-10 for crushed rock fines)
0-8 (0-10 for crushed rock fines)
All base materials shall require approval, by performance testing, in accordance with Part 2 of The Structural Design of Heavy Duty Pavements for Ports and other Industries.
Within The Structural Design of Heavy Duty Pavements for Ports and other Industries, aggregates for use in CBM2 must comply with the requirements shown in the table below.
|5% fines value||BS 812-111|
No restrictions on chemical properties are specified. However, in certain circumstances, the Environment Agency in England and Wales, (or their equivalent in Scotland and Northern Ireland) will require that the construction activities will not lead to contamination of ground or surface waters due to leaching or spillages. For this reason you are advised to discuss, as a matter of routine, your intended application with the relevant regulatory authority.
Assessment of the leaching potential is likely to involve laboratory testing to BS EN 1744-3: 2002, and/or BS EN 12457-3: 2002, and/or EA NEN 7375:2004. In order to correctly assess acceptability, the test results will need an appropriate interpretation, which may take allowance of leaching processes in situ as opposed to in the laboratory. For further information on these issues download the Environmental Information Sheet.
revised: 19 Feb 2010
The information set out above is only concerned with the technical aspects of construction and is of a general nature only and not intended to be relied upon in specific cases.
It is derived from currently available UK Standards and Specifications applicable at the time of writing. Reference should be made to the relevant Standards and Specifications applicable at the time of writing and you should seek and rely upon expert professional advice on specific issues.
The information does not take account of environmental issues which you should discuss as a matter of routine with the regulatory authorities (the Environment Agency in England and Wales, the Scottish Environment Protection Agency in Scotland and the Department of the Environment in Northern Ireland).
Consequently, the information is provided only on the condition that WRAP and their sub-contractors will not be liable for any loss, expense or damage arising from your use or application of such information. See clause 3 of our Terms and conditions.