News  2004                   News 2003  News 2002

Wainwright News

Autumn 2004

NVQ Awards

Six more candidates have completed their NVQ's in a rolling

programme that is expected to see all drivers and operators to have

obtained an NVQ in their main jobs by January 2005

Pictured at a presentation in October 2004 with Managing Director, Peter Barkwill (centre) are, from left to right: Nigel Beaver, Level Four in Management and Level Two in Specialised Plant & Machinery Operations, Mike James, Ashley Marks and Paul Godden, all with Level Two loading shovel, David Kent NVQ Level Three in Management and Andy Open, certificate for In-house Examiner/Assessor for Mobile Plant.

Other News ...

New European Standards for Aggregates

.

From 1 January 2004 the current British Standards for Aggregates used in the construction sector such as BS882, BS1199/1200 and BS63, will be replaced with a new series of European Standards for Aggregates for concrete, mortar, asphalt or in their unbound and hydraulically bound forms.

Whilst the aggregates remain the same, the terminology, product descriptions, standard sieve sizes, grading presentation, test methods, Factory Production Control (FPC) and CE Marking will change.

.

.

For aggregates for asphalt and surface treatments, the product standard is BS EN 13043 with the supporting National Guidance given in PD 6682-2. The importance of the National Guidance cannot be over emphasized since it identifies the critical details of the common European product standard and highlights how it should be applied in the UK .

Particular guidance on the relevant aggregates test methods is given in PD 6682-9. The following issues will be of particular interest to all producers, specifiers and users.

Aggregate sizes

As described in BS EN 13043, aggregate sizes are expressed in terms of “d/D” with the guidance given in PD 6682-2 providing a table of recommended sizes that represent the best match to current production. For example, 20mm single size becomes 10/20 for general use in asphalt and 14/20 for surface treatments and chippings. Note that 2mm is now the break point between fine and coarse aggregate.

Gradings

PD 6682-2 sets out recommended sieves for use in the UK and thus steers all parties to the use of common sizes, avoiding unnecessary confusion. The new grading procedure places greater emphasis on “consistency of product” and is based on the declaration of the producers' “typical” grading with controlling tolerances and overall requirements on designated sieves. This represents a move away from a rigid compliance envelope and the risk of wide variations during supply.

Fines quality

The new test for fines quality, the methylene blue test, is not considered sufficiently precise by the UK for the assessment of harmful fines (clay) content and it is recommended that the existing approach of complying with the fines content limit or evidence of satisfactory use is maintained.

Shape of coarse aggregate

The “flakiness index” is retained as a term, but the test method and equipment are new and there is no correlation with the BS 812 test which will be withdrawn. PD 6682-2 gives guidance on recommended values. The new test for “shape index” effectively replaces the BS 812 elongation test, which again will be withdrawn, and assesses the relationship between the maximum and minimum dimensions of individual particles. This new test is not recommended for use in the UK .

Crushed and broken surfaces

This new test assesses the potential for mechanical interlock between the coarse aggregate particles and is not considered necessary in the UK .

Angularity

This test has no history of use in the UK and again is not recommended.

Resistance to fragmentation

The 10% fines test is replaced by the Los Angeles test. Since the tests do not measure the same properties, there is no direct correlation. Guidance on the required Los Angeles values is given in PD 6682-2 for general uses and experience of satisfactory performance will be taken into account until further research can clarify the position.

Highway surfaces

Polished Stone Value (PSV) and Aggregate Abrasion Value (AAV) tests are the same as the existing BS methods. However, abrasion from studded tyres is not relevant to the UK . The guidance given in the Highways Agency design manual remains valid.

Resistance to wear

The new micro-Deval test assesses the resistance to wear, particularly where particles are in contact and subject to movement. This requirement is not considered relevant to asphalt applications.

Durability

Due to the long-term experience in the UK the magnesium sulphate soundness test is recommended in preference to the new freeze/thaw test. Although the soundness test is the same as the current BS method, care needs to be taken with the reporting of the results - they are now reversed! There is little experience of the new freeze/thaw test in the UK and its use is not recommended.

Resistance to thermal shock

This new test assesses the potential for material degradation during the drying process. It is not recommended for use in the UK .

“Sonnenbrand” of basalt

This new test assesses the potential for rock decay. It is not applicable to UK materials, but may have some value in respect of imported basalt aggregates.

CE marking

The new product standard sets out the minimum requirements for a factory production control system, declaration of conformity of the essential requirements and hence CE marking. Based on safety criteria - skidding resistance - aggregates having a PSV of 58 or above must be subject to Attestation Level 2+, but for all other purposes Level 4 is applicable.

Note: please see: www.qpa.org for further information.