POROUS PAVEMENTS. - Advantage Asphalt - APWA Spring Conference April 2016

Transcription

1 POROUS PAVEMENTS - Advantage Asphalt - APWA Spring Conference April 2016 John Hickey, P.E., Esq. Executive Director Asphalt Pavement Association of Oregon

2 Surface Selection and Disaster Preparedness Factors to consider Resistance to cracking Speed of construction Asphalt Flexible Fast construction time

3 Reduce impervious surface Recharge ground water Improve water quality Eliminate need for detention basins Reduce permitting requirements Why Porous Pavements?

4 Goals for Oregon Develop High-Quality Mixes Avoid Areas of Poor Site Conditions Educate Designers, Contractors, and Owners Implement Lessons Learned

5 Port of Portland Terminal 6 Pringle Creek Green Streets

6 The Auto Warehousing Corporation (AWC) needed to expand their facilities in Northwest AWC offloads imported cars AWC needed the improvements to be constructed in the summer of 2006 Designers considered dense and porous Port of Portland - Terminal 6

7 Port of Portland - Terminal 6 Porous Considerations AWC needed project completed in 2006 Traditional surface would require changes to existing outfall to Columbia River and pre-treatment Permitting the outfall work would have resulted in construction in 2007, possibly later, much later

8 Port of Portland - Terminal 6 Porous Considerations Site was previously filled with 6-8 feet of dredge sand Porous could be finished in 2006 Shorter project = less cost Avoiding outfall permitting = less cost and time Groundwater recharge Lower life cycle costs

9 Port of Portland Terminal 6 Porous: 35.7 acres Impervious: 15.4 ac. 100% onsite stormwater management through porous and vegetated swales Swales for stormwater from impervious area

10 Port of Portland - Terminal 6 Owner: Port of Portland Civil Engineer: Century West Engineering Landscape Architects: GreenWorks Porous Pavement Consultant: Cahill Associates Prime Contractor: Coffman Excavation Paving Subcontractor: Lakeside Industries

11 Port of Portland Terminal 6 Used Cahill Associates standard spec. modified for local practice 3 porous surface using ½ mix 1 choker course AASHTO No coarse aggregate uniformly graded, clean, crushed, approximately 40% air voids

12 Port of Portland Terminal 6 Used PG binder Preventing drain down is critical 5.6% AC content ½ open graded ACP

13 Port of Portland Terminal 6 Used offset MTV, to help uniformity and stay out of paver path 12.5 to 15 ft. wide pulls Approximately 2000 tons/shift Night Paving Lakeside used a 500 ton/hour plant and paved at night Avoided having to waste material between types of mix Shorter run times because of lighter traffic

14 Port of Portland Terminal : 9 years and still performing great. Minor surface raveling in a couple small spots.

15 Better Port of Portland Terminal 6 Chose asphalt for performance history Visited six concrete sites found spalling, clogging, poor ride Faster Could not have met AWC timeline with any other surface treatment Lower Cost Concrete estimates varied 2 to 4 times higher than asphalt

16 Port of Portland Terminal 4 Road project with sections of dense graded and porous asphalt Original Design 6 inches of AASHTO No. 57 (choker) No polymer modification to porous binder No RAP allowed in dense graded sections Triangular sections at intersection of porous and dense

17 Port of Portland Terminal 4

18 Port of Portland Terminal 4

19 Port of Portland Terminal 4

20 Port of Portland Terminal 4 Final Design 1.5 inches of AASHTO No. 57 (choker) Polymer modification to porous binder 30% RAP allowed in dense graded mix Triangular sections squared off Completion: November 2015

21 Port of Portland Terminal 4

22 Port of Portland Terminal 4

23 Port of Portland Terminal 4

24 Port of Portland Terminal 4

25

26 Pringle Creek Community

27 Pringle Creek Community Late season paving required addition of 8 pit run (clean 4-0) Eliminated geotextile underneath the pit run

28 Pringle Creek Community

29 Pringle Creek Community Paving asphalt treated permeable base (ATPB) 3 lift 3% asphalt 30%-35% voids Paved full width Crowned section 2½%

30 Pringle Creek Community Requires extra attention Repair damage as you go For two lift system can eliminate choker course

31 Base paving was completed before utilities Pringle Creek Community How do you keep it clean? Contractor had the idea to cover it all with a Geotextile

32 Pringle Creek Community And then winter came early November storms gave us record rainfall of more than 11 Lots of wind as well

33 Pringle Creek Community Utilities installation moved on in wet conditions Utility trench was up to 6 wide and 6 deep all in winter

34 Pringle Creek Community April 2007 Utilities all in Grading complete Sidewalks, curbs and some landscaping complete All in winter/spring running on the ATPB

35 Contractor removed geotextile and cleaned surface to prepare for top lift Pringle Creek Community

36 Pringle Creek Community Sieve Top Lift % Passing 1/ /8 97 1/4 55 #4 34 #8 7 #30 3 # Asphalt % 6.0 Binder PG ER (Polymer Modified)

37 Pringle Creek Community The completed project came out very nice. Performing fantastically today 9 years.

38 Pringle Creek Community

39 Pringle Creek Community

40 Pringle Creek Community Concrete Spalling Cracked

41 Pringle Creek Community Asphalt 200,000 Square Feet - variable width, 2 lifts Total paving days = 6 Prep between lifts = 2 Concrete 20,000 square feet Total paving days = 10 Cure time = 28 days

42 Asphalt 4-1/2 5 Base & Top + Prep + Geotexile = $2.45/ft 2 Pringle Creek Community COST Concrete 6 pervious = $5.00/ft 2

43 October 8, 2015 Pringle Creek Community

44 Pringle Creek Community 10/8/15

45 Pringle Creek Community 10/8/15 Porous Concrete - cracked

46 Pringle Creek Community 10/8/15

47 Pringle Creek Community 10/8/15

48 General Observations/Recommendations A key to performance: high quality stone base/reservoir course For fine grained soils reservoir course should be a min of 18 For thicker, multiple lift asphalt sections, you can eliminate the choker course Asphalt Base should be ATPB Design so the percent voids and void size increase with depth Polymer-modified binder in wearing course

49 Mix Design Dense-Graded Mixes 96% aggregate and asphalt binder 4% voids 92% primary compaction 4% secondary compaction Specific gravities volumetrics VMA: 13 17% Common Problems Using higher than needed mix level Using stiffer than needed asphalt binder

50 Mix Design Porous Mixes % aggr. and asphalt binder % voids Secondary compaction less critical Specific gravities volumetrics VMA: 20 30%

51 Key Porous Mix Properties Voids permeability Asphalt Content durability Draindown permeability and durability Moisture Susceptibility permeability and durability

52 Mix Design Common Porous Mix Problems No stiff polymer-modified binder in wearing course Assuming can pave in marginal temperatures Ignoring compaction proper compaction will not clog pores if proper gradation used Subgrade must be flat and uncompacted

53 Mix Design Porous Mixes Select gradation see limits in One gradation to start Select asphalt binder grade Generally 2 grades stiffer on high end Climate: PG Porous: PG Polymer-modification in wearing course

54 Porous Mixes Mix Design Volumetrics: prepare samples for bulk and maximum specific gravity (density) testing Calculate VMA and VFA Draindown: test by pyrex method at 4.5%, 5.5%, and 6.5% asphalt Fibers may help

55 Porous Mixes Mix Design Asphalt binder content: Pick based on results of volumetrics and draindown testing Moisture susceptibility TSR testing using a surrogate dense graded mix from same source Production: must analyze film coating and adjust if needed

56 Key Porous Mix Properties Voids permeability Asphalt Content durability Draindown permeability and durability Moisture Susceptibility permeability and durability