1 / 17

Jaco Liebenberg Dennis Rossmann Philip Joubert

Innovations on the Asphalt Mix Design for the Rehabilitation of National Route 3 between Mariannhiill and Key Ridge. Jaco Liebenberg Dennis Rossmann Philip Joubert. Overview . Introduction to project Structural design limitations Mix design requirements Mix design process

oriole
Download Presentation

Jaco Liebenberg Dennis Rossmann Philip Joubert

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Innovations on the Asphalt Mix Design for the Rehabilitation of National Route 3 between Mariannhiill and Key Ridge Jaco Liebenberg Dennis Rossmann Philip Joubert

  2. Overview • Introduction to project • Structural design limitations • Mix design requirements • Mix design process • Mix design performance tests & results • Construction

  3. Introduction • N3/1&2 Mariannhill – Key Ridge • Main link Durban - Gauteng • Constructed in 1985 • 40 to 50 million E80’s • Constructed as • Maintenance • 1994/5 (+14 years) • Identified for Rehabilitation • 2006 (+20 years) 13 mm Bitumen rubber seal 40 mm AC 40 mm AG 125 mm AC 300 mm C3 subbase 150 mm G7 selected CBR 3 subgrade

  4. Introduction • Major typical defects • Rutting in slow lane • Some isolated rutting in middle lane • Cracking and pumping in slow lane • Design traffic • Design requirements • Slow lane: Substantial pavement required • Middle lane: Some repairs required • Fast lane: None required

  5. Pavement Design Options ? mm Concrete overlay ? mm overlay 40 mm AC 125 mm AC 300 mm C3 subbase 150 mm G7 selected CBR 3 subgrade

  6. Pavement Design Options 40 mm AC 125 mm AC 300 mm C3 subbase 150 mm G7 selected CBR 3 subgrade

  7. Pavement Design Options 300 mm C3 subbase 150 mm G7 selected CBR 3 subgrade

  8. Structural design • Stabilised subbase performed well • Only localised repairs required • Not thick enough for traffic volume (req 450 mm) • Asphalt inlay considered most appropriate • Mix design to compliment structural design • Stiff as possible (req: E = 4 000 Mpa) • Slow lane • Signs of stripping in lower part of layer  replace all asphalt • Selective repairs of subbase • Middle lane • Some cracking and deformation  Only repair upper 80 mm • Fast lane • Only Isolated repairs • New surfacing over full width Paper discuss process to consider for restrictions in structural design by optimising the asphalt mix design

  9. Mix design requirements • Primary requirements • Rut resistant • Stiff (≈ 4 000 MPa) • Fatigue resistant • Secondary requirements • Low permeability • Good moisture susceptibility • Mix design process • Standard mix design process • 2 mix designs in parallel – selection process • Much emphasis on performance testing • Performance tests on mixes from trial sections

  10. Mix design • Aggregate and grading • Coarse aggregate quartzite • Fine aggregate: quartzite & tillite mix • Bailey method to determine optimum grading • Contained 15 % RAP • Binders • Two binders evaluated • A-P1 (4% EVA) with Optimum binder Content @ 4.2% • vs. A-E2 (3.5% SBS) with Optimum binder Content @ 4.4% • Min component of mix design: • Performance under accelerated testing • 6 trial sections constructed • Directly north of toll Plaza in slow lane • A-P1 mix: 3.9% 4.2% and 4.5% • A-E2 mix: 4.0% 4.3% and 4.6%

  11. Trial sections • From trial sections (extracted from pavement) • 228 cores • 16 beams • Tested for • Rut resistance under MMLS and Hamburg wheel tracking • Moisture susceptibility under MMLS and mod. Lottmann • Permeability • Fatigue

  12. Deformation and rutting resistance • MMLS testing and Hamburg wheel tracking tests • Also discussed in paper by Hugo et.al

  13. Fatigue resistance • Coarse rut resistant mixes generally poor fatigue • Beams extracted from pavement • 6 beams for 4.2% A-P1 tested • 6 beams for 4.3% A-E2 tested • Fatigue test • 4 point bending beam • Constant strain

  14. Adopted mix design • A-P1 mix considered most appropriate mix • Better rut resistance • Better moisture susceptibility • Fatigue comparable to A-E2, within acceptable guidelines • A-E2 probably suitable as well • Performance tests  A-P1

  15. Construction • High level of control  comfort design intent is built • Tight control of • Mix properties • Compaction • Ability to project trends and act pro-actively • Construction quality • No rejected work or rework on Asphalt base • Some issues recently with UTFC  currently being investigated

  16. Conclusions • Limitations during structural design • Possible to optimise mix design to compliment structural design • Require cooperation • Asphalt mix design process • Benefits not a standalone process • Tie in with pavement design • Attention to mix design • mix appropriate for application • considers unique requirements for application

More Related