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, 17 2016

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

23 March, 2016 Presentation Title Page 2

Outline

– 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

1) Current practices

(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 www.bbacerts.co.uk

Main references

– Asphalt options: • European (harmonised) guides, eg: BS EN 13108 series • National guides, eg: BSI PD 6691 • (SRN) Proprietary products - HAPAS documents

– Installation requirements – national guides: • Laying - BS 594897 • Permanent works - SHW (August 2008), updates in 2016? • (SRN) Proprietary products - HAPAS documents

– Test methods: • European (harmonised) guides, eg: BS EN 12697 series • Current BS 598 series

BS EN 13108 – Bituminous Mixtures

Implemented since January 2008 Guidance on the use is detailed in BSI PD 6691

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

Asphalt durability tests: according to EN

8

Wear Tests – simulative? CEN/TC227/WG1 – prCEN/TS 12697-50:2014

23 March, 2016 Page 9

– Asphalt materials are “live” products, subject to changes

– Resistance against degradation in service, due to changes in chemical-mechanical properties

– What causes these changes: • Thermal? Hot, cold, frost • Loss of volatile components? • Moisture? Winter maintenance?

Page 10

2) UK Surfacing System – Design for Durability

11

Balancing Act

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

Permitted Surfacing Options (UK Design Manual for Roads and Bridges)

– HAPAS – Bond coat

Current Test Methods – British Board of Agrèment HAPAS

14

LABORATORY

INSTALLED

23 March, 2016 Presentation Title Page 15

Requirements

23 March, 2016 Presentation Title Page 16

Update in 2016?

– 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 12 – 24 months

– Air voids (if declared), up to 24 months

23 March, 2016 Page 17

Installation Trial – Performance Monitoring

– 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

23 March, 2016 Page 18

Performance Guarantees

Performance Band Description Pass / Fail

criteria

Excellent No discernible fault Pass

Good No significant fault Pass

Suspect Seriously faulted Fail

Poor Requires remedial treatment

Fail

Bad

Requires immediate remedial treatment

Fail

Failures of Thin Asphalt Surfacing

19

Why treatment is required during <5 years?

Source: Neal ::0:::

Fretting, 61% Cracking, 35% Delamination, 4% Source: TRL Report 674 (2010)

Key requirements for durable surfacing

20

Source: J.C. Nicholls, “Permanent Potholes Repair”, Asphalt Professional No 60, 2014

A. Highways England/Mineral Product Associations/Eurobitume UK – research on durable thin surfacing (2015 – 2016)

B. Highways England/Defence Infrastructure/Associations of Directors for Economic, Environment, Planning and Transportation – research on asphalt preservative treatments (2010 – 2011, 2012 – 2013)

C. Highways England/Defence Infrastructure – research on durable surface treatments (antiskid/HFS/slurry surfacing) (2014 – 2015)

23 March, 2016 Page 21

3) Recent Updates

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

Page 23

Desk Study – Collaborative Research

workmanship

Construction method

Traffic management

Joints

Impermeability Air voids

Dense

Macro texture

Specification

Mix design

QA/QC

Aggregate

Filler

Binder content

Quality

PMB, additives

Wet friction PSV

Case Studies & Feedbacks from: Australia – France – Germany – Netherland - New Zealand – England – Scotland – South Africa - USA

Binder

Layer thickness

Bond coat

Performance related criteria

Workshop – June 2015

– 6 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

Summarised Concepts

25

Dual layer

Imprinted Texture

AC Surface

Market Additives

Blue Sky Additives

Modular/ Pre-fab

Coatings

Artificial Agg

Ease

of i

mpl

emen

tatio

n

Durability

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

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

– 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

B – Research on Preservative Treatments for Asphalt Surfacing

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?

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?

What happens in practice?

23 March, 2016 Presentation Title Page 31

PPM

Surface course

Substrate

Diffusion? Slow process? f(time, temperature)?

23 March, 2016 Preservative Maintenance Page 33

Viscous to Elastic Transition (VET) Temperature (0.4Hz)

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

SATS – Saturated Ageing Tensile Stiffness

– Stiffness before SATS conditioning (ITSMu)

– Stiffness after SATS conditioning (ITSMc)

– Retained stiffness = 𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝑟𝑟 = 𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼

35

Modified condition: 0.5MPa, 85oC, 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.

Dense Semi-dense Porous

WAC leachate Asphalt Treatment Type Threshold Values

SS SS ES ER

WAC Inert Waste

WAC SNRHW and non-

hazardous deposited

in the same cell

WAC hazardous

waste

Limit of reporting

Co

ncu

lsio

ns

Inert waste result Less than inert

SNRHW result Less than SNRHW

WAC

Less than SNRHW

WAC

Hazardous waste Less than hazardous

Determined Values

WA

C D

eter

min

ed b

y L

each

ing

Arsenic 0.02 0.01 0.01 0.88 0.5 2 2.5 <0.1 Barium 1.2 1.2 0.89 51 20 100 300 <1 Cadmium 0.02 0.02 0.02 0.03 0.04 1 5 <0.02 Chromium 0.1 0.1 0.1 0.91 0.5 10 70 <0.1 Copper 1.0 0.9 1.1 4.1 2 50 100 <0.1 Mercury 0.002 0.002 0.002 0.02 0.01 0.2 2 <0.01 Molybdenum 0.1 0.1 0.1 3.2 0.5 10 30 <0.1 Nickel 0.23 0.13 0.15 8.3 0.4 10 40 <0.1 Lead 0.05 0.05 0.05 0.29 0.5 10 50 <0.1 Antimony 0.05 0.05 0.05 0.86 0.06 0.7 5 <0.02 Selenium 0.03 0.17 0.19 0.37 0.1 0.5 7 <0.02 Zinc 0.2 0.15 0.17 24.0 4 50 200 <1 Chloride 600 410 400 100 800 15000 25000 <1 Flouride 7.5 4.4 5.0 1.8 10 150 500 <3.5 Sulfate 850 994 816 110 1000 20000 50000 <200 Phenols 1.0 1.0 1.0 1.0 1 <1 Dissolve Organic Carbon 270 295 295 160 500 800 1000 <100 Total Dissolve Solids 3500 3816 3316 570 4000 60000 100000 <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.

23 March, 2016 Page 37

Cook, J. 2015. 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

– 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

Summary of findings

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

4) Concluding Remarks

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.

Thank You

Daru.Widyatmoko@Aecom.com 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