Durability in the UK Mix Design and Specifications

Transcription

1 Durability in the UK Mix Design and Specifications 2016 NCAUPG Technical Conference, March 17-18, 2016 Indianapolis, IN Daru Widyatmoko Technical Director, Pavement Design and Asset Management, Centre of Excellence for Asset Consultancy, Nottingham March,

2 Outline 1) Current practices 2) UK surfacing systems 3) Recent updates case studies a) Next generation of asphalt surfacing b) Durability of preservative treatments 4) Concluding remarks Presentation Title 23 March, 2016 Page 2

3 1) Current practices Standard route (harmonised EN, BS) Proprietary route (HAPAS, Highways Authority Product Approval Schemes) Strategic Road Networks (SRN) Contract Documents and Specifications Performance related or guarantee? Page 3

4 (BBA) HAPAS (British Board of Agrément) Highways Authorities Product Approval Scheme Certification for proprietary products Asphalts and binders modified by polymers and other performance enhancing additives SG3 Thin surface course systems SG4 Modified binders Guidelines and certificates available on-line via

5 Main references Asphalt options: European (harmonised) guides, eg: BS EN series National guides, eg: BSI PD 6691 (SRN) Proprietary products - HAPAS documents Installation requirements national guides: Laying - BS Permanent works - SHW (August 2008), updates in 2016? (SRN) Proprietary products - HAPAS documents Test methods: European (harmonised) guides, eg: BS EN series Current BS 598 series

6 BS EN Bituminous Mixtures Implemented since January 2008 Guidance on the use is detailed in BSI PD 6691

7 Reference to: SHW Clause 900 and NG 900 Series BS594897

8 Asphalt durability tests: according to EN 8

9 Wear Tests simulative? CEN/TC227/WG1 prcen/ts : March, 2016 Page 9

10 2) UK Surfacing System Design for Durability Asphalt materials are live products, subject to changes Resistance against degradation in service, due to changes in chemicalmechanical properties What causes these changes: Thermal? Hot, cold, frost Loss of volatile components? Moisture? Winter maintenance? Page 10

11 Balancing Act 11

12 Required Properties of Surfacing (UK Design Manual for Roads and Bridges) Durability Resistance to deformation Load spreading ability Texture depth Skidding resistance Low noise generation Layer adhesion Waterproofing Ease of laying Resistance to cracking Resistance to moisture damage Ride quality

13 Permitted Surfacing Options (UK Design Manual for Roads and Bridges) HAPAS Bond coat

14 Current Test Methods British Board of Agrèment HAPAS LABORATORY INSTALLED 14

15 Requirements Presentation Title 23 March, 2016 Page 15

16 Update in 2016? Presentation Title 23 March, 2016 Page 16

17 Installation Trial Performance Monitoring Visual inspection, from 0, 12, 24 months Surface macrotexture, from 0, 12, 24 months In situ bond with substrate, early life Noise (if declared), between months Air voids (if declared), up to 24 months 23 March, 2016 Page 17

18 Performance Guarantees SHW Clause 942 thin surface course system Visual condition during the first 2 years must be Good Free from fretting, ravelling, stripping and aggregate loss during the first 5 years Performance Band Excellent Good Suspect Poor Description No discernible fault No significant fault Seriously faulted Requires remedial treatment Pass / Fail criteria Pass Pass Fail Fail Bad Requires immediate remedial treatment Fail 23 March, 2016 Page 18

19 Failures of Thin Asphalt Surfacing Source:Neal (2015) Fretting, 61% Cracking, 35% Delamination, 4% Source: TRL Report 674 (2010) Why treatment is required during <5 years? 19

20 Key requirements for durable surfacing Source: J.C. Nicholls, Permanent Potholes Repair, Asphalt Professional No 60,

21 3) Recent Updates A. Highways England/Mineral Product Associations/Eurobitume UK research on durable thin surfacing ( ) B. Highways England/Defence Infrastructure/Associations of Directors for Economic, Environment, Planning and Transportation research on asphalt preservative treatments ( , ) C. Highways England/Defence Infrastructure research on durable surface treatments (antiskid/hfs/slurry surfacing) ( ) 23 March, 2016 Page 21

22 A Research on durable thin surfacing (2015/2016) Developing the Clause 942 Thin Surface Course Replacement more durable but retained good surface texture and low noise

23 Desk Study Collaborative Research Case Studies & Feedbacks from: Australia France Germany Netherland - New Zealand England Scotland South Africa - USA Traffic management workmanship Construction method QA/QC Joints Performance related criteria Layer thickness Specification Impermeability Dense Air voids Macro texture Bond coat PMB, additives Filler Binder content Mix design Aggregate Binder Quality Wet friction PSV Page 23

24 Workshop June Highways Authorities 10 major surfacing contractors (MPA) 4 major bitumen suppliers (Eurobitume UK) 3 research universities 10 major consultants 2 overseas French and German designers 24

25 Summarised Concepts Market Additives AC Surface Dual layer Blue Sky Additives Imprinted Texture Ease of implementation Coatings Modular/ Pre-fab Artificial Agg Durability 25

26 Good Practice Applies to each Concept Better understanding of aggregate packing Improvements to mix design process Improving workmanship / operational upskilling / training Procurement and risk sharing / investment in plant and equipment / visibility of programme Better feedback loop on performance Substrate condition Bond between layers Access / traffic management / full road closure improved safety and joint workmanship / enable echelon paving Relationship with supply chain Temperature control (use of shuttle buggies) 26

27 Research on durable surfacing progress to date 1. Two identified candidates Next generation Hot Rolled Asphalt (HRA) small size chipping Dual layer premium asphalt surfacing volumetric controls, AC-SMA? 2. Laboratory mix design trials completed 3. Demonstration trial, planned for May 4. Other parallel works: Binder spectroscopy at traffic speed Volumetric assessment of installed thin surfacing Simulative durability tests 27

28 B Research on Preservative Treatments for Asphalt Surfacing Benefits highlighted Restore binder properties Seal pavement from water ingress and oxidation Improve durability by combination of the above Type of Pavement Preservation Materials Sealers, to preserve and protect from further deterioration Rejuvenators, as sealers but incorporate rejuvenating agent

29 Questions Initial skid resistance? Reduction in permeability, how this may affect porous asphalt or PFC? Improve mechanical properties? Improve durability, resistance to age & moisture? How long the good thing lasts? Is it effective? Acceptance criteria?

30 Further Questions Direct blending bitumen and preservative binder for lab test does it represent what happens in situ? Initial softening (e.g. reduction in viscosity or increase in penetration) is it a good thing? What kind of interaction is taking place initially and later in service? Representative sampling, top/bottom/middle? How long the good thing lasts? Is it effective?

31 What happens in practice? PPM Surface course Substrate Diffusion? Slow process? f(time, temperature)? Presentation Title 23 March, 2016 Page 31

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33 Viscous to Elastic Transition (VET) Temperature (0.4Hz) Preservative Maintenance 23 March, 2016 Page 33

34 Samples for testing laboratory Asphalt cores Porous Asphalt/Friction Course (PA/PFC) Stone Mastic Asphalt (SMA) Dense Asphalt Concrete Preservative materials: Emulsion based - sealer Solvent based - sealer Emulsion based - rejuvenator

35 SATS Saturated Ageing Tensile Stiffness Dense Semi-dense Porous Stiffness before SATS conditioning (ITSMu) Stiffness after SATS conditioning (ITSMc) Retained stiffness = IIIIIIIIrr = IIIIIIIIII IIIIIIIIII Modified condition: 0.5MPa, 85 o C, 24 hours The prefix AC, SMA and PFC denote asphalt concrete, stone mastic asphalt and porous friction course respectively The last two letters SS, ES, SR and ER denote solvent based sealer, emulsion based sealer, solvent based rejuvenator and emulsion based rejuvenator respectively. 35

36 WAC leachate Conculsions WAC Determined by Leaching Inert waste result SNRHW result Hazardous waste Asphalt Treatment Type SS SS ES ER Less than inert Less than SNRHW WAC Less than SNRHW WAC Less than hazardous WAC Inert Waste Threshold Values WAC SNRHW and nonhazardous deposited in the same cell WAC hazardous waste Limit of reporting Determined Values Arsenic <0.1 Barium <1 Cadmium <0.02 Chromium <0.1 Copper <0.1 Mercury <0.01 Molybdenum <0.1 Nickel <0.1 Lead <0.1 Antimony <0.02 Selenium <0.02 Zinc <1 Chloride <1 Flouride <3.5 Sulfate <200 Phenols <1 Dissolve Organic Carbon <100 Total Dissolve Solids <2 Notes Exceed Inert WAC Exceeds SNRHW Note: SNRHW denotes stable non-reactive hazardous waste SS, ES, SR and ER denote solvent based sealer, emulsion based sealer, solvent based rejuvenator and emulsion based rejuvenator respectively.

37 Cook, J Development of Maintenance Techniques and Specifications to Improve Performance, VFM and Sustainability of MOD Runways. 6th Global Airfield Engineering & Maintenance Summit, 9-10 September. London 23 March, 2016 Page 37

38 Summary of findings The binder ageing protocol is able to rapidly identify different PPM products by their ageing characteristics and indicates when re-treatment might be required. A suite of laboratory assessments which were carried out on highway and airfield materials before and after treated with different PPMs presented the benefits from applying the treatment at the correct application and frequencies. The effectiveness of these preservatives varies with each PPM type and the condition and type of asphalt surfacing which will receive the treatment. 23 March, 2016 Page 38

39 4) Concluding Remarks a) Key to durability complete circle & interdependent process, from specification, design, installation to in service performance b) Durable surfacing system: requirement v practical challenges c) Fretting on thin asphalt surfacing: good practices v design d) Preservative treatment: sound screening v treatment plan 23 March, 2016 Page 39

40 Disclaimers The views expressed in this presentation are those of the presenter and not necessarily those of the organisation he represents. The presented works and case studies were kindly supported by many parties and organisations; their contributions are gratefully acknowledged.

41 Thank You AECOM, Pavement Design and Asset Management, Centre of Excellence for Asset Consultancy 12 Regan Way, Chetwynd Business Park, Chilwell. Nottingham NG9 6RZ, United Kingdom March, 2016