Asphalts in road construction. Edited by Dr Robert N. Hunter. Thomas Telford, London

Transcription

1 Asphalts in road construction Edited by Dr Robert N. Hunter Thomas Telford, London

2 Contents 1. Assessing aggregates for use in asphalts Preamble Why test aggregates? Classifying aggregates Natural rock types Artificial/synthetic aggregates Recycled aggregates Aggregate petrology a simple classification Important studies relating petrology to aggregate properties Sources of high quality aggregates in the UK Use of aggregates for asphalts around the world Basic problems with the way that aggregates are 1.9. tested Aggregate properties relevant to asphalts Current test methods for assessing aggregates Summary of main aggregate testing requirements Main test methods used to assess the properties of aggregates Sampling Size distribution Relative density and water absorption Cleanliness Shape Strength Proposed European norms Selection of test methods Summary Bitumens Preamble The nature of bitumen 45

3 xvi CONTENTS Saturates Aromatics Resins Asphaltenes Physical properties of bitumen Production of bitumen Specification of bitumen Current UK practice European specifications Performance specifications Rheology Terminology and theory Rheological tests and data manipulation Relationship of rheological parameters to mix performance Bitumen modification Polymer modification Storage stability Production considerations for polymer modified binders The effects of polymer modification Other bitumen modifiers Emulsions and cutbacks Cutback bitumen Bitumen emulsion Testing of bitumen emulsions and cutback bitumens Performance specifications for emulsions and cutbacks Foamed bitumen Natural bitumen Trinidad Lake Asphalt (TLA) Gilsonite Rock asphalt Tar Health and safety aspects Summary Functions and properties of road layers Preamble The ideal pavement Design concepts The subgrade The foundation Bituminous roadbases and basecourses Wearing courses Hot-rolled asphalt (HRA)

4 CONTENTS xvii Porous asphalt (PA) Asphaltic concrete and dense bitumen macadam (DBM) Stone mastic asphalt (SMA) Thin surfacings Comparison of wearing course characteristics Skid resistance Measuring the mechanical properties of road layers The Nottingham Asphalt Tester The Falling Weight Deflectometer The Dynamic Cone Penetrometer Summary Design and maintenance of asphalt pavements Preamble Introduction Volume 7 of the Design Manual for Roads and 4.4. Bridges 146 Overview of pavement structure, type and performance Pavement types Pavement performance HD 35 technical information Traffic assessment Pavement wear factors The standard method of traffic assessment The structural assessment and maintenance method Heavy duty asphalt pavements The influence of vehicle speed on pavement design Design of pavement foundations Assessment of the subgrade Sub-base and capping Drainage Frost resistance Stabilized sub-base and design for performance Design of asphalt thickness the empirical approach Staged construction design for 20 years initial life Pavements of indeterminate life Roadbase and basecourse materials Clause 929: Design, Compaction Assessment and Compliance of Roadbase and Basecourse Macadams Design curves normal pavements 165

5 xviii CONTENTS Design curves long life pavements Asphalt in rigid composite pavements Design of asphalt thickness the analytical approach The Shell Pavement Design Method NOAH Use of stiffness data in analytical design COST333/AMADEUS Widening of pavements and haunch strengthening Widening with additional lanes Haunch strengthening and local widening Asphalt substitution Assessment skid resistance Surface texture Measurement of microtexture the PSV Test Aggregate selection Measurement of macrotexture Measurement of skid resistance Skid resistance and accident risk Assessment structural conditions Routine structural assessment programme The High Speed Road Monitor Visual condition surveys Deflection surveys Using deflection to estimate residual life Planning an investigation data review The detailed investigation Falling weight deflectometer and ground radar Design of maintenance treatments Design of structural maintenance Wearing course replacement Overlay Reconstruction Minor repairs and surface treatments Asphalt surfacing and surfacing materials Aggregate selection Tyre-generated noise British Board of Agrement/HAPAS Hot rolled asphalt wearing course Porous asphalt Thin surfacings Stone mastic asphalt Bitumen macadam wearing course Retexturing of asphalt surfacing Summary

6 CONTENTS 5. Production: processing raw materials to mixed materials Preamble Raw materials Crushed rocks Sand and gravel Blast furnace slag and steel slag Resources Methods of producing aggregates Hardrock crushing and screening plant Limestone crushing and screening plant Sand and gravel processing plants Methods of producing asphalts Conventional asphalt batch plants Batch heater plant Drum mixer Counterflow drum mixer Summary of main features of asphalt production plants Controlling manufacture Aggregate processing plants Hot rolled asphalt and coated macadam plants Summary xix Surfacing plant Preamble Lorries Pavers Elements of a paver How asphalt flows through a paver Action of the screed The screed Automatic control devices Integral sprayer 250 Paver delivery systems Compaction plant Dead weight tandem and three-point rollers Pneumatic tyred rollers Vibrating rollers 258 Ancillary equipment Milling machines Chipping machines Hot boxes Infrared heaters 262 Summary

7 xx CONTENTS Good surfacing practice Preamble Safety Site safety policy Site safety officer Control and monitoring General site safety Precautions for paver work Environmental issues Estimating for work Materials Programme Cost Price Planning and programming Pre-start inspection Ordering plant, equipment and materials Ordering plant and equipment Ordering materials Surfacing operations checklist Transportation Setting out 285 Laying Use of a block-up staff Laying asphalts by hand Machine laying Laying thin surfacings and SMAs Repair to and reinstatement of thin surfacings and SMAs The application of precoated chippings into HRA wearing course Rolling and compaction Rolling patterns Correlation between layer thickness and density of the compacted mat Factors affecting rolling technique and the achievement of optimum mat density Vibratory compaction Quality control and checks The gang The plant The weather Condition of the site The material Other factors 317

8 CONTENTS xxi Requirements of the Specification for Highway Works Series 700 Road Pavements General Series 900 Bituminous Bound Materials Economic analysis of operations Estimate summary Cost/value Remedial works Summary Compaction of asphalts Preamble Importance of compaction Published work Effects of compaction on pavement performance Rolling methods Compaction plant Other factors affecting compaction Compaction specification Background Series 700 Road Pavements General Series 900 Road Pavements Bituminous Bound Materials Use of 'may lay'/'may not lay' diagrams Practical application of compaction technology General Vibrating rollers versus static rollers The compaction of chipped HRA wearing course The compaction of thin surfacings The compaction of HMB Rolling patterns Dynapac's PaveComp 0 Computer Program Summary Standards for testing Preamble Sampling Precision Test methods Composition of asphalts Bitumen tests Mixture design Adhesion Percentage refusal density Texture depth 421

9 xxii CONTENTS Wheel-Tracking Test Creep Test Elastic stiffness Analysis of test results Statistical techniques Control charts Significance testing Recommendation Laboratory management Asphalt Quality Assurance Scheme Summary Specialist surface treatments Preamble Surface dressing Surface dressing specification Factors which influence the design and performance of surface dressings Types of surface dressing The Road Note 39 design approach Surface dressing equipment Types of surface dressing failures Surface dressing season Safety Crack sealing/overbanding Slurry surfacings/micro-surfacings Footway slurry Thin carriageway slurries Thick carriageway slurries Micro-asphalts Airfield slurries Usage, materials and developments High friction surfacings Bitumen-extended epoxy resins Epoxy resin Polyurethane resin Acrylic resins Thermoplastic rosin esters Mastic asphalt Thin surfacings Multiple surface dressing Ultra thin hot asphalt laid by paver Thin polymer modified asphaltic concrete Stone mastic asphalt (SMA) Coloured surfacings Incorporating coloured pigments into the asphalt 501

10 CONTENTS xxiii Application of coloured chippings to the asphalt Application of a coloured surface treatment Coloured aggregate bound by a conventional bitumen " Coloured aggregate bound by a translucent binder Asphalt recycling In situ recycling Off-site or plant recycling HAPAS the Highway Authorities Product Approval Scheme Summary Failures in asphalts and how to avoid them Preamble Roadbases The subgrade The sub-base The roadbase Basecourses Wearing courses Common HRA wearing course failures Other failures Summary Index 550