瀝青路面微表處實驗特征.pdf

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1、Our mission is to Keep Alaska Moving through service and infrastructure.Alaska Department of Transportation&Public FacilitiesMicrosurfacing Experimental FeatureMinnesota Drive RampsDrew Pavey Pavement ManagementNovember 20232Why Microsurfacing Looking for an economical solution to fix rutsAlternativ

2、e to mill/fill 2”to fix a”problem It is used widely in the lower 48Emulsion,aggregate,additives Source:Ingevity North Dakota Asphalt Conference Future of Micro Surfacing,20183History of Micro Approached about using micro 10-15 years agoBut testing showed it would fail under studded tire wear Used th

3、e Prall test to simulate wear Cant move forward until a formulation does resist stud wear Approached again in 2016 Highly polymerized binders can now be emulsified(PG64-40)Tests came back with good resultsStainless Ball Bearings4Project Selected-Minnesota Ramps Placed on Minnesota RampsRuts had deep

4、ened,added a pre-level to rut fill on some ramps(change order)Did crack filling and then a tack coat prior to microsurfacing applicationSee Dimond ramp pre-level below5Our Micro Formulation Mix Design Performed September 2019 Preliminary testing showed the microsurfacing with PG64-40 was prone to ru

5、tting.We allowed it to be adjusted to a PG64-34 to reduce binder softness.Prall results were not as good but were acceptable.Mix design showed the mix was slow set,so a pneumatic roller was planned to help set the micro6Mix Design 1 The original mix design was performed using the PG64-34 emulsion Se

6、ptember 2019.Only one piece out of spec:We were informed highly modified micros typically perform well even if out on this.This test informational,so allowed it.7Test Strip June 2020(start of COVID 9 months later)Slow set used roller to force water out.Took 2 hours.Told from hot emulsion would be fa

7、ster cure in production.8Production Day 1 Started off smooth,then things went south3 hours to get roller on micro slower,not faster than test stripIn curves on ramp started breaking too fast clogging in spreader boxSo,it is becoming unworkable but not hardening Lots of testing done to determine what

8、 changed Informed the binder was different.Oil production shut down different reaction from original mix design.9Shut Down Production-Testing Ramps reopened after about 3 hours shut down production to investigate Shut down for 2 days(also due to weather)Additives were changed from Lime to Cement and

9、 Aluminum Sulphate.New Mix Design Performed.This change allowed rollers to get back within 2 hours.Now lateral displacement is within spec 10Thought Things Were Good Production continued seemed to be going smooth International Airport Ramps Flushed/Damaged11Friction Testing/Removal From the flushing

10、 distress there was a friction concern Performed friction testing showed loss in flushed areas mill/fill with 1.5”HMA at 5 ramps with friction loss.Most ramps removed were being used to haul gravel to AIA.Heaviest loads.Remaining ramps are being monitored.This year the final report going out on for

11、the ramp performance and lessons learned.12Monitoring Performance is mixed based on original ramp conditionCracks reflected through(expected)Ramps that were in poor condition are back in poorRamps that were fair or good are in fair or good condition Cored and Prall tested the micro post-construction

12、Needed value after changing additivesUnfortunately,increased to 30 not resistant to studsCement likely made brittle,prone to wear13100th Avenue NB Off Ramp14100th Avenue SB On Ramp15International Cloverleaf16Closing Thoughts Think ramp deformation was from slow set mix hit by heavy trucks Unsure if raveling is caused by change in additives(aluminum sulphate)On the fly changes added uncertainty to projectQuestions?Drew Pavey andrew.paveyalaska.gov