Asphalt Mixtures. What they are. Road Pavement Terminology. Andy Simms Jacobs Laboratories. Road Surface. Surface Course Binder C ourse.

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1 Road Pavement Terminology Asphalt Mixtures Road Surface What they are Pavement Surface Course Binder C ourse Surfacing Andy Simms Jacobs Laboratories Formati on Level Bas e Sub Base Capping Layer Foundation Sub grade 1

2 UK Materials Hot Rolled Asphalt Hot Rolled Asphalt Asphalt Concrete (Coated Macadam) Stone Mastic Asphalt Thin Surface Course Systems (Proprietary) Developed after WW1 by Richardson Relies on strength from sand / filler bitumen mortar Aggregate pads out mix Characterised by Gap Grading High binder content = expensive Can be used for base, binder surface & regulating course 2

3 HRA 30/14 Surface Course Hot Rolled Asphalt Surface Course Coarse Aggregate 30% 30 or 35% mixtures to be used w ith superimposed coated chippings 55% High Stone content mixtures (no chippings) Sand 53% Limestone filler 10% Bitumen 7% 3

4 Road Surfacing Materials - Skidding Resistance Hot Rolled Asphalt Properties All speeds Microtexture Additional at high speeds Polishe d Stone Value of aggrega te Macrotexture (Surface Tex ture ) Impermeable Durable Fatigue Resistant Workable when installed (easy to compact) Prone to Deformation 4

5 Hot Rolled Asphalt Properties - Deformation Asphalt Concrete (Coated Macadam) For merly Coated Macadam Developed in 19 th Century John Macadam Characterised by Continuous Grading Relies on strength from mechanical interlock of aggregate particles Tar w as first binder used Patented tar mac Low er binder content Can be used for base, binder surface & regulating course 5

6 AC 32 Dense Base Asphalt Concrete Properties Coarse Aggregate ~70% Fine Aggregate ~20% Bitumen ~4% Filler ~7% Relatively permeable (particularly Close Graded mixtures) Durable when compacted correctly (and in the case of Close Graded surface course mixtures when they are sealed during early service life) Deformation Resistant, good load spreading properties Fatigue damage (cracking) if stiff mixtures are laid too thin Design mixtures difficult to compact- require high compactive effort Surface courses can be fluxed 6

7 Surface Fretting Thin Surface Course Systems Developed in 1990s French and German Technology Modified by TRL Further developed into manufacturers proprietary systems Characterised by high stone content 7

8 Thin Surface Course Systems Thin Surface Course Systems Binder is usually Fibre modified and / or contains Polymer Modified binder () They come in three, ready to wear sizes, categorised by layer thickness <18mm 18-25mm >25mm <50mm Ultrathin Thin Not so thin 8

9 Thin Surface Course Systems Thin Surface Course Systems (Proprietary Names) TSCS may be categorised by the following terms:- Supplier Aggregate Industries Mat erial Name Hite x SMAp ave Agg. sizes (mm) Binder or fib res SMAt ex or fib res Polymer - modified Asphaltic Concrete Paver-laid Surface Dressing Microasphalt Thinpave Safedress Saf epave Premierpave Stratag em Bitumen, & fibres Bitumen, & fibres or Fibre Han son Durafalt Fibres Tuffgrip Tuffpave and have lots of sexy names.. 9

10 Thin Surface Course Systems (Proprietary Names) Thin Surface Course System Properties Jean Lefeb vre Gripfibre (3 g rad es) 6 & fibre s Lafarge Ce me x Tarmac TotalFina UL-M Axofibre Axofl ex Axophone Viapave Viatex Masterpave Masterphalt Masterflex Masterphalt-P Finatex Surphalt, 6 6, 6, 6, 6, 6 6, 10? 6, 10? Fibres Fibres Fibres Fibres emul sion emul sion Can be impermeable (dense mixtures) or relatively permeable (open mixtures) Durable when compacted correctly (and in the case of Close Graded surface course mixtures when they are sealed during early service life) Deform ation Resistant Difficult to hand lay (ironwork) Require use of tack coat or bond coat Quiet Reduced Spray 10

11 HAPAS Certificate HAPAS - Highway Authorities Product Approval Scheme New Materials including Thin Surf ace Course Systems Proprietary systems, e.g. Masterpave, Axoflex, Durapave Specif ied through SHW Clause 942 Approv al through BBA Two y ear guarantee HAPAS Key Points Product Certification Scheme Operated by British Board of Agrément BBA Technical content defined by industry/clients Designed to ensure innovative / proprietary products w ill perform Based on four stage Type Approval Product Conformity Certification Ongoing Surveillance 11

12 HAPAS Guidelines and Certificates TSCS Properties Certificate describes the material and states the performance achieved by the product in the standard tests (on laboratory or site samples) The Guideline sets out the tests a product undergoes the performance levels to be achieved (Level 3 is alw ays better than Level 1) Requirements are developed and agreed by Client and Industry reps in a Specialist Group Thin Asphaltic Concrete 4 years old Paver Laid Surface Dressing 6 years old 12

13 Early Life Skidding Resistance 13