All change for asphalt
The withdrawal on the 1 January 2008 of the existing British Standards for asphalt and their replacement with new European Standards represents a change for the road-surfacing sector on an unprecedented scale. However, Colin Loveday, director of technology at Tarmac and chairman of the British Standards Committee for highway materials, believes that the UK can take the changes in its stride provided suppliers and purchasers address the issues now.
The UK asphalt industry is gearing up for some major changes that will impact on highway authorities and other specifiers across the UK. From 1 January 2008, the existing British Standards for asphalt, (BS 4987-1 and BS 594-1), will be withdrawn and replaced with a new European Standard BS EN 13108.
Because this change is driven by European Directives, we dont have the option of staying as we are - everyone will be legally obliged to switch to the new standards. Product descriptions will change on 1 January 2008 and it is important that those involved in the industry discuss and understand the practicalities on ongoing contracts well in advance of the deadline.
Daunting? It could have been, but, thankfully, a lot of work has gone on behind the scenes to soften the impact. Over many years, as part of the British delegation to European Standards, we have worked hard to make sure that the materials we traditionally use in the UK were included and also that terminology changes were kept to a minimum.
After twelve months of hard work by the QPA and BSI committees of which Tarmac is part of both - the key document, BSI Guidance Document PD 6691 on the use of EN 13108, was published in July. Whilst this has involved a lot of work behind the scenes for companies like Tarmac, it will make the transition as painless as possible for customers.
Conforming with EU directives
A key aim of the EU is to break down restrictive trade barriers, open up commercial markets and create a more competitive trading environment. Individual national standards are perceived as potential barriers to open trade so the EU has set about their removal through two key European directives the Construction Products Directive (CPD) and the Public Procurement Directive (PPD).
The CPD works through the process of CE marking of products. A producer CE marks as a legal declaration of the products constituents, conformity and performance, showing that it has undergone all the necessary testing and is fully compliant with the European Standard.
The PPD places an obligation on public purchasers to accept CE marked products and generally to specify in terms of Harmonised European Standards.
Critically, this means that European Standards have a quite different status to British Standards.
01.01.08 deadline in the UK
Although the official date for legal implementation of the new standards is April 2008, UK will implement the change on the 1 January 2008. This date has been chosen, as it is the time when the lowest numbers of transactions take place, ensuring minimal disruption everyone involved.
It is important to note that the change will be absolute. It is not possible to operate dual standards, so from the beginning of next year, UK specifiers and producers alike will be obliged to use the new standards.
BS EN 13108 scope and change
BS EN 13108 replaces a series of UK standards including BS 594 (hot rolled asphalt) and BS 4987 (coated macadams). BS 598 which relates to asphalt testing - will also be withdrawn and new, wide-ranging test procedures introduced with a new European standard called BS EN 12697.
Perhaps one of the most noticeable changes will concern product descriptions. The UK term macadam no longer features in the standards. Although the materials remain, they will now described as Asphalt Concrete (AC).
Binder penetration will no longer be referred to by a single pen number such as 50 pen or 125 pen, but rather as the grade designation, for example 40/60 or 100/150, from EN 12591, the European bitumen standard
However, although the names will change, the structure of the descriptions will be very similar AC 20 dense bin 40/60 for example replaces 20mm DBM BC 50.
BS EN 13108 is split into seven parts covering the different types of asphalt used across the EU, some specifically designed to deal with extremes of climate not experienced here. UK applications will be almost exclusively Asphalt Concrete (macadams), Hot Rolled Asphalt (HRA) and Stone Mastic Asphalt (SMA) covered by parts 1, 4 and 5 and this is the focus of the National Guidance Document PD 6691.
EME2, the high performance base and binder course material currently being introduced for trunk road and motorway use in the UK, is covered in EN 131081 and a full UK specification is provided in PD 6691 with Type Testing protocols in BS 594987.
EN 13108 1 Asphalt Concrete
EN 13108 2 Asphalt Concrete for thin layers
EN 13108 3 Soft Asphalt
EN 13108 4 Hot Rolled Asphalt
EN 13108 5 Stone Mastic Asphalt
EN 13108 6 Mastic Asphalt
EN 13108 7 Porous Asphalt
Bold denotes materials used in typical UK environment
Provision for Recycling
A significant addition within the new European Standards is the inclusion of regulations to govern the use of reclaimed asphalt and recycling. EN 13108-8 looks at the specification and description of Reclaimed Asphalt, and the asphalt standards include specific requirements relating to recycling.
Until now, recycling of asphalt in the UK has been done by a process of agreement and departure, as there is no provision for recycling built into current British asphalt standards. Many parts of Europe Germany and the Netherlands in particular - are more developed than the UK with respect to recycling and the UK stands to benefit from this experience, with the EN standards including provisions for up to 60 per cent recycled content. This should enable a more sustainable product, taking advantage of the important ability of asphalt to be 100% recyclable as new asphalt.
Help is at hand - National Guidance document - PD 6691
The switch to European Standards is a more fundamental change than we have seen before in the asphalt sector, bringing the potential for misunderstanding and error.
This has been recognised and, under the umbrella of BSI, a team of people drawn from all sides has worked closely together to produce guidance documents and enabling specifications. PD 6691, the National Guidance document to BS EN 13108, is the key paper for preparing future asphalt specifications in the UK. It comprises the following:
Box out by magazine A general explanation of the new standards and how they differ from British Standards
An example specification for macadams, dense macadams and EME 2 which can be used as a direct replacement for BS 4987.
An example specification for HRA, which can be used as a direct replacement for BS 594.
An example specification for SMA in a familiar UK style.
The example specifications include 1:1 equivalents to all current materials complete with EN13108 shorthand designations. Where current UK specifications contain performance requirements, such as void content, stiffness, or deformation resistance, equivalent performance categories from EN13108 have been included.
It is important that everyone involved familiarises themselves with the PD 6691 specifications and adopts them in contracts and purchasing.
Guidance on test methods - PD 6692
Supporting the new standards are 44 test method standards, which replace the UK tests previously covered in BS598. Whilst many of these are similar to our current tests, there are some significant changes, for example in wheel tracking tests, which create the need for work to establish appropriate limits for UK conditions. A separate BSI Guidance Document, PD 6692 is available which describes these changes.
Conformity -Type Testing and Factory Production Control
In line with all European Standards, the new asphalt specifications require a declaration of conformity to be provided by the producer in the form of a CE Mark Certificate. There are two parts to the required procedure: Type Testing, to EN 13108-20 (which is basically proof testing of all of the properties of the target mix composition); and Factory Production Control to EN 13108-21 (which is the operation of a quality system to ensure consistent and compliant manufacture).
Type Testing is designed to become a universal replacement for mixture approval trials on contracts with materials submitted pre-certified with CE marks for the required performance properties. Protocols for this have been included in BS 594987, based very closely on the relevant clauses from the Specification for Highway Works, which is itself in the process of changing to align with the new standards.
Factory production control is covered in BS EN 13108-21 and is similar to a QA scheme, involving requirements for managing production, inspection and test. It sits alongside (and will form much of the schedule for) the HA Sector Scheme 14. The new standard has led to some small changes to the Sector Scheme 14, although these are very minor and the supplier is still required to look at customer complaints, customer feedback and customer service as part of the QA process.
The way in which the standards deal with conformity will impact on those involved in acceptance testing. Under British Standards, around 80% of asphalt in the UK was supplied under fixed compositional recipe standards, which made such compliance testing quite simple. The new standards are based on tolerances applied around producers target compositions, which will be different for each mix formulation from each source. Therefore, conformity assessment will need to be referenced back to this individual mix data.
Laying and compacting new Standards
To add to the complexity of the situation, January 2008 will also see the introduction of a new British Standard for transportation, laying and compaction of asphalt - BS594987 - to replace BS594-2 and BS4987-2. BS 594987 has a significantly broader scope than the former British Standards.
A full revision is also underway of the 900 series of the Specification for Highway Works (SHW) aimed at the 2007 November amendment. This will align SHW with EN13108 and BS594987. During this revision, the opportunity is being taken to incorporate significant improvements to laying techniques to enhance the durability and integrity of asphalt pavements.
Towards the future
Change is on its way for asphalt. On the plus side, the industry is well advanced in its preparations, and guidance papers are available from the QPA, which is also running explanatory seminars around the country.
Although Tarmac has been closely involved in the evolution of the new European standards for more than a decade, we have also been working hard behind the scenes since the beginning of this year to help smooth the transition to the revised standards for customers. Staff have received extensive training so that they can help advise customers through the change; IT systems and databases have been updated in anticipation; literature and asphalt converters have been created; marketing and training sessions for clients to explain the new requirements are being organised; quotations, delivery tickets and invoices are already showing the new mix designations alongside the old ones; and laboratories have been reequipped and testing is in hand to validate against the new requirements.
It is now important that detailed discussions take place up and down the supply chain within individual contracts so that come next January there are no misunderstandings about what requirements for asphalt materials and laying apply in each situation.
There is no reason why it should not be business as usual on 1January 2008, but to ensure the successful changeover to the European Standard, preparation over the next few months will be vital. But rest assured, if you are buying asphalt now, you will still be able to buy it next year - it might just be called something different!
24 August 2007
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