Service life of asphalt materials for asset management purposes

Transcription

1 Service ife of asphat materias for asset management purposes Minera Products Association mpa asphat Minera Products Association

2 2 - SERVICE LIFE OF ASPHALT MATERIALS FOR ASSET MANAGEMENT PURPOSES Asphat is part of the Minera Products Association () - the trade association for the aggregates, asphat, cement, concrete, dimension stone, ime, mortar, and siica sand industries and is the sectora voice for minera products. Its membership aso incudes companies manufacturing road construction and quarrying pant and equipment and UK producers of petroeum bitumen. The vaue of the oca road network to both authorities and society cannot be underestimated practicay every journey starts and ends on a road and they are essentia to safe and timey transport of peope, goods and services. Having an accurate picture and understanding of that vaue and its deterioration is key to the successfu impementation of Highways Asset Management Pans. The joint working group from and ADEPT members is to be commended for its efforts in providing this too to assist Asset Managers. Aan Mackenzie, Chairman, Asphat ADEPT is the Association of Directors of Environment, Economy, Panning and Transport. The Association of Directors of Environment, Economy, Panning & Transport is an umbrea organisation representing oca authority county, unitary and metropoitan Directors responsibe for Pace based services. Our remits incude economic deveopment, transport and communications, panning and housing and the environment. I am deighted that ADEPT and have joined together in this initiative to estabish the service ife of various asphat materias. It is an exceent exampe of coaboration as Highway Authorities trave the road of Whoe Government Accounting. To depreciate the network it is essentia that Authorities, at the outset, have a guideine for asset managers as to how ong asphat materias shoud be expected to ast. Heather Barnes, President, ADEPT Whist every care is taken to ensure the accuracy of the genera information and advice offered herein or given by staff of the Minera Products Association and ADEPT, no iabiity or responsibiity of any kind can be accepted by the Minera Products Association, the ADEPT or their staff. Cover photography courtesy of Aggregate Industries

3 3 - SERVICE LIFE OF ASPHALT MATERIALS FOR ASSET MANAGEMENT PURPOSES Contents page item 4 Executive Summary 5 Introduction 5 Methodoogy 6 Surface Course Description Service Life 6 Binder Course and Base Description Service Life 7 Guidance to foow to achieve ife 7 Key compromising factors 8 Faiure modes 9 Recommendation 10 References 10 Bibiography 10 Gossary 11 Working Group Members

4 4 - SERVICE LIFE OF ASPHALT MATERIALS FOR ASSET MANAGEMENT PURPOSES Executive Summary Service ife is defined as the period of time for which asphat materias after first instaation are fit for purpose and as such can be used for asset management purposes. The ife of a pavement is the time at which significant maintenance becomes necessary. On any given road the materias may have a greater or esser ife depending upon circumstances. Treatments to extend service ife are aso addressed. A sound basis for understanding the service ife of asphat materias used in highway maintenance and construction is an essentia eement of ifecyce panning for the highway practitioner with regard to asset management and the requirements for depreciation, vauation and Whoe of Government Accounts (WGA). The work undertaken by a joint working group of ADEPT and representatives has provided a guideine for asset managers on service ife vaues for use by Highway Authorities. They are recommended to the Chartered Institute of Pubic Finance and Accountancy (CIPFA) and the Highway Asset Management Financia Information Group (HAMFIG) as the service ife vaues to be used uness other specific performance data is avaiabe to justify aternative figures. The foowing summarises the service ife figures: PAVEMENT LAYER MATERIAL MATERIAL SERVICE LIFE IN DESIGNED ROADS MATERIAL SERVICE LIFE IN EVOLVED ROADS Surface course Asphat concrete HRA Thin surface course system SMA a) Low texture b) Other 8 years 15 years 15 years 6 years 10 years 10 years Binder course Asphat concrete EME 2 HRA SMA A 30 years Base Asphat concrete EME 2 HRA A 40 years

5 5 - SERVICE LIFE OF ASPHALT MATERIALS FOR ASSET MANAGEMENT PURPOSES Introduction A Highway Authorities shoud be producing ifecyce pans for their assets in order to cacuate the annua depreciation of those assets; this wi be reported in Whoe of Government Accounts (WGA) as required by DfT. A key part of any ifecyce pan is understanding what the asphat materia options are and how ong they wi ast. In the absence of robust, ong-term records based on actua performance, which few authorities currenty have, the service ives identified in this document shoud ony be used to aow the production of Lifecyce pans. A Highway Authorities are encouraged to coect and anayse data as part of their asset management in order to provide feedback to future reviews of this document. This wi enabe them to verify that the service ives quoted are vaid for their situation or to enhance the information from actua data. It is recommended that authorities use the figures pubished in this report where reevant in producing ifecyce pans to support WGA financia reporting uness, or unti, robust oca data is avaiabe that demonstrates a different eve of performance on their roads. This document has been recommended to HAMFIG (Highway Asset Management Financia Information Group) and CIPFA (Chartered Institute of Pubic Finance and Accountancy) as the way forward and the basis for ifecyce panning and asset vauation regarding these asphat materias. Methodoogy A group consisting of members of Asphat Technica Pane together with members of ADEPT Sois & Materias Design & Specification Group representing materias technica speciaists met in workshops to discuss service ife. The aim of the workshops was to seek agreement as to the expected service ife of asphat materias used in highway maintenance and construction. The output was subsequenty reviewed by both parties and refined at joint meetings. The service ife of an asphat materia, after first instaation, is its expected ifetime foowing which it is no onger fit for purpose. The Group reached consensus on the service ives that pavement ayer materias wi attain if design and construction are undertaken in accordance with required practice. The sections beow on Guidance to foow to achieve service ife and Key compromising factors give advice on such practice. Each pavement ayer materia is considered against the foowing headings: Description/Definition Service ife Guidance to foow to achieve service ife Key compromising factors Faiure modes (surface course ony) The Group considered the issue of designed and evoved roads. Designed roads are those that were constructed foowing a pavement structura design process whereas evoved reates to those roads that have been historicay treated in some way over time without any forma initia design. Different service ives are provided for materias in both designed and evoved types.

6 6 - SERVICE LIFE OF ASPHALT MATERIALS FOR ASSET MANAGEMENT PURPOSES Surface course DESCRIPTION What is incuded? The use of asphat materia as a surface course in highway maintenance is a ong estabished and proven technique. This report considers the foowing: Asphat concrete a continuousy graded mixture of minera aggregate, fier and bituminous binder which forms an interocking structure. Thin surface course system paver aid surface course materias instaed between 15 and 50mm thick. SMA a very high stone content, gap-graded mixture with high binder content. HRA a dense mixture of minera fier, sand and bitumen into which a coarse aggregate is added. It is a gap-graded materia and the mechanica properties are dominated by the mortar. Coated chippings may be appied to achieve texture. If specific proprietary materias are used from suppiers Authorities shoud seek performance information reated to those products as it may be different to the ives proposed in this document. Which roads are incuded? A casses of road, from singe track, uncassified roads to nationa high speed motorways can, and have had asphat materias successfuy appied. SERVICE LIFE The Group gave due consideration to service ife on carriageways when designed and constructed correcty based on standard pavement design. It is anticipated that the characteristic ife across the whoe network in the appropriate appication wi refect these service ives. MATERIAL MATERIAL SERVICE LIFE IN DESIGNED ROADS MATERIAL SERVICE LIFE IN EVOLVED ROADS Asphat Concrete e.g. 8 6 AC dense, AC cose Hot Roed Asphat (HRA) Thin Surface Course Systems (TSCS) e.g. C Stone Mastic Asphat (SMA) a. Low texture b. Other NOTE: HRA and ow texture SMA are more abe to accommodate the variabiity of evoved roads. It is recognised that various Highway Authorities around the UK utiise asphat materias on footways providing simiar ife to carriageways however the Group did not address footways and this may be rectified in the future. Binder course and base DESCRIPTION Binder course provides a we-shaped surface upon which the surface course is aid, contributes to structura strength and waterproofing Base main structura ayer that takes designed oading over the ife of the pavement What is incuded? The foowing asphat materias are incuded as binder course materia: Asphat concrete EME 2 HRA SMA SERVICE LIFE BINDER COURSE When the pavement and materias are correcty designed and instaed, binder course materias wi have a service ife of 30 years. BASE When the pavement and materias are correcty designed and instaed, base materias have a service ife of 40 years.

7 7 - SERVICE LIFE OF ASPHALT MATERIALS FOR ASSET MANAGEMENT PURPOSES Guidance to foow to achieve ife Key compromising factors Design to standards and specifications and with suppy chain invovement Cient competence RN42 appies Importance of bond coat Pre-surfacing requirements to be determined e.g. pre-patching, raising ironwork Determine specification Contractors must be certified to and compiant with Nationa Highway Sector Scheme (NHSS) 16 Trained workforce contractors must demonstrate their workforce competency is up to date Service ife assumes sound substrate Consideration of avaiabe fexibiity or stiffness of existing substrate Drainage of whoe pavement structure The key compromising factors are the factors most ikey to affect the service ife figures quoted above and wi not be an issue if the guidance is foowed. Such factors may incude: Night work Wrong materia in wrong pace Use of non-sector Scheme registered contractor Incorrect preparation of works Incement weather conditions Surface conditions (note 8) Appication to paned surface Compaction Segregation Poor substrate Poor finish / ongitudina profie Incorrect bond coat Maintenance of drainage Materia seection Surfacing conditions cod/ wet winter night to hot/dry summer day Each of these factors can have a significant effect and increased risk of reduction in ife and the tota effect wi be cumuative. Any singe factor coud have a reducing effect of 5% whist cumuative effects coud tota as much as 75% in extreme circumstances.

8 8 - SERVICE LIFE OF ASPHALT MATERIALS FOR ASSET MANAGEMENT PURPOSES Faiure modes The foowing are faiure modes that can occur in the surface course. Different materias wi have different modes of faiure: Poishing of aggregate Loss of texture Chipping oss/stripping Rutting Joints / raveing Fatting up Cracking Beeding Tearing Fretting NOTES 1. Consider road hierarchy reated to traffic eves. 2. Determine the reason to appy new surface ensure it is the correct soution. 3. Faiure can be a resut of a change in site circumstance e.g. channeized traffic oading resuting in rutting. 4. Correct binder type and quantity is essentia to achieve ife. 5. Consider suitabiity of substrate condition/affinity to sub-grade. 6. Need to appy at the right time as this affects maintenance panning and contract preparation to ensure a the necessary sites can be incuded. HRA gives a good indication of future faiure hence time to pan whereas SMA can be more instant and wi require patch and hod pending work at the appropriate time. 7. Consider drainage at site ocation i.e. whether the defect is a consequence of water ponding or fowing over the surface or in the pavement structure or sub-grade. This wi need attention prior to surfacing if it is to survive the service ife. 8. Surface conditions must be right such as no standing water; no residua sat; no detritus, and vegetation free. 9. Materias to be aid at the most advantageous time of year; in genera terms this means March to November, athough some products are designed to be aid outside this working window.

9 9 - SERVICE LIFE OF ASPHALT MATERIALS FOR ASSET MANAGEMENT PURPOSES Recommendation A Highway Authorities are recommended by ADEPT and the to use the service ife for asphat as stated in the foowing tabe when producing ifecyce pans for asset management and to support WGA financia reporting uness, or unti, robust oca data is avaiabe that demonstrates a different eve of performance on their roads for the pavement materias used: PAVEMENT LAYER MATERIAL MATERIAL SERVICE LIFE IN DESIGNED ROADS MATERIAL SERVICE LIFE IN EVOLVED ROADS Surface course Asphat concrete HRA Thin surface course system SMA a) Low texture b) Other 8 years 15 years 15 years 6 years 10 years 10 years Binder course Asphat concrete EME 2 HRA SMA A 30 years Base Asphat concrete EME 2 HRA A 40 years NOTE: HRA and ow texture SMA surface courses are more abe to accommodate the variabiity of evoved roads. The above has been recommended to HAMFIG and CIPFA by ADEPT as the way forward and the basis for ifecyce panning and asset vauation regarding these asphat materias.

10 10 - SERVICE LIFE OF ASPHALT MATERIALS FOR ASSET MANAGEMENT PURPOSES References Gossary Road Note 42 (2008), pubished by TRL NHSS 16 Nationa Highway Sector Scheme for the Laying of Asphat Mixes MCHW Voume 1 Specification for Highway Works BS EN Bituminous mixtures Materia specifications ADEPT CIPFA CSS DfT Association of Directors of Environment, Economy, Panning and Transport Chartered Institute of Pubic Finance & Accountancy County Surveyors Society (now ADEPT) Department for Transport Bibiography Design Manua for Roads and Bridges (DMRB) (Vos 0-15) PD 6691 Guidance on the use of BS EN Bituminous mixtures Materia specifications BS Asphat for roads and other paved areas. Specification for transport, aying, compaction and type testing protocos. LR1132 The Structura Design of Bituminous Roads, TRL 1984 We Maintained Highways a Code of Practice for highway maintenance, UKRLG, updated 2013 CSS ENG/6-94 Pavement Design Manua EME 2 Énrobe á modue éevé EN European Norm (Standard) HAMFIG Highways Asset Management Financia Information Group HRA Hot Roed Asphat Minera Products Association NHSS Nationa Highway Sector Scheme RN42 Road Note 42 SMA Stone Mastic Asphat SMDS ADEPT Sois & Materias Design & Specification TRL Transport Research Laboratory WGA Whoe of Government Accounts Code of Practice on Transport Infrastructure Assets, CIPFA, 2013

11 11 - SERVICE LIFE OF ASPHALT MATERIALS FOR ASSET MANAGEMENT PURPOSES Working group members ADEPT representatives Steve Betteridge John Booth Stephen Chid Bob Noakes David O Farre Ian Wash Chris Aen Smith Secretary, SMDS Group Member, SMDS Group Chairman, SMDS Group Member, SMDS Group Member, SMDS Group Member, SMDS Group Asset Management representatives John Bradshaw-Buock Robert Gossing John Lay David Markham Pau Phiips John Richardson Macom Simms Iain Simpson Chris Southwe

12 16 - SAFE BITUMEN TANK MANAGEMENT Asphat is part of the Minera Products Association, the trade association for the aggregates, asphat, cement, concrete, dimension stone, ime, mortar and siica sand industries. Asphat June 2015 Asphat Giingham House, Giingham Street London SW1V 1HU Te +44 (0) Fax +44 (0) mpaasphat@mineraproducts.org ADEPT Buckinghamshire County Counci, County Ha, Waton Street, Ayesbury, Bucks HP20 1UA Te +44 (0) adept@buckscc.gov.uk