Toni Carroll - Superpave in California
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Presentation delivered at the CalAPA Spring Asphalt Pavement Conference April 9-10, 2014 in Ontario. Topic: New Superpave specification coming to California.
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Toni Carroll - Superpave in California
- 1. Superpave The New Frontier Toni Carroll Vulcan Materials
- 2. Why Superpave? Improve Performance ◦ Low Temp Cracking ◦ Fatigue Cracking ◦ Rutting Materials ◦ Binder ◦ Aggregate ◦ Mix Design & Testing Testing & Performance Prediction
- 3. Job Format? No more QCQA! Most jobs are Standard Some jobs are Method
- 4. Changes to Mix Specifications Tighter Specs ◦ Air Voids ±1.5% ◦ Binder for HMA: -0.3%, +0.5% ◦ Binder for Rubber: -0.4%, +0.5% No more VFA VMA Design Vs. Production
- 5. Changes to the Mix Higher Binder Contents ◦ Compactor changes volumetrics ◦ Rubber binder content is now a minimum of 7.5 TWM (8.1 DWA)
- 6. Changes to the Mix Coarser gradations FAA required for ALL mixes, More fractured faces
- 7. Change to Fractured Face Method Currently a particle is considered crushed if 25% of the face is fractured. New procedure requires 50% of the face to be fractured. 2x more fracture!
- 8. Compaction: Kneading vs. Gyratory HVEEM Compactor uses “kneading” motion to compact pucks ◦ Tamping rod presses down in various places around the puck Gyratory Compactor uses “gyrating” motion to compact pucks ◦ Surface the same size as the puck is rolled in a circular fashion around the puck
- 9. Time Saved with Gyratory Task HVEEM Gyratory Grading Aggs 60 60 Mixing 45 45 Compacting 15 20* Cool Down for Stability 90* - Stability Test 25 - Cleanup 20 20 TOTAL (Minutes): 255 145 TOTAL (Hours): 4.25 2.4 Technician’s Time: 2 hrs 45 min 2 hrs 5 min *Does not require technician to be present
- 10. Cost to Purchase Compactor: $40k Accessories: $8k Construction Costs: $0k-$10k TOTAL CAPITAL COST: $48,000-$58,000
- 11. Cost to Outsource Field Samples: $900-$1200 Lab Mixed Designs: $5400-$7500
- 12. What to Do on Your Job Avg. Caltrans job may have 20,000- 30,000 tons of mix Need Mix Design Need to test for Verification Need to test for Production Startup Need one test for every 4,000 tons Avg Testing for Job: 5-10 samples
- 13. Hamburg Wheel Track General Overview Weighted steel wheel runs back and forth over HMA samples in a heated water bath
- 14. Test Purpose Predicts: ◦ Rutting Fatigue ◦ Moisture Susceptibility ◦ Stripping Mix Fails Due To: ◦ Weak aggregate structure ◦ Inadequate binder stiffness ◦ Moisture damage
- 15. Caltrans’ Reason for HWT No stability test Rutting potential Tests for moisture sensitivity & stripping To be used with TSR
- 16. How will your mix fare? Stiffer asphalt binders (higher high temperature grades) do better Adding liquid antistrip or lime usually improves the HWT results. Improvement with lime is usually more dramatic than with liquid Harder aggregates do better (Igneous vs. limestone) Stone on stone mixes do better than dense mixes
- 17. Time Required for One Lab Mixed Test Task Minutes Hours Grading Aggs 60 1.00 Mixing 45 0.75 Compacting 20-210 0.33-3.5 Cutting, Prep, & RICE 45 0.75 Achieving Temperature 60 1.00 Testing 20,000 Passes 390 6.50 Cleanup 20 0.33 TOTAL: 640-830 10.5-14
- 18. Cost to Purchase HWT Machine: $60k Accessories: $2k Professional Installation: $1.2k (Optional) Crane: $3k Construction Costs: $5k-$30k TOTAL CAPITAL COST: $71,000- $96,000
- 19. Cost to Outsource Only a few 3rd party machines in the state Field Samples: $900-$1700 Lab Mixed Samples: $1200-$2000
- 20. What to do on Your Job Avg. job may have 20,000-30,000 tons of mix Need one test for Mix Design/Verification Need one test for Production Startup Need one test for every 10,000 tons Avg Testing for Caltrans Job: 3-5 samples
- 21. Hamburg & TSR Testing Can not hand mix samples for mix design test results Must be run through the hot plant for mix design testing (also counts as verification sample) TSR no longer a ratio, must pass dry & wet strength minimum specifications Freeze thaw required
- 22. Hamburg & TSR Testing Cont. If you cannot meet the minimum HWT or TSR requirements you must test PI and treat your mix using a specified antistrip treatment
- 23. HWT Sample Amts Mix Design/Verification Production Startup 1 per 10,000 tons or 1 per project, whichever is greater 4 Pucks ≈ 9200 grams (Per Split)
- 24. TSR Sample Amts Mix Design/Verification Production Startup 1 per 10,000 tons or 1 per project, whichever is greater 6 Pucks ≈ 21,600 grams (Per Split)
- 25. Gyratory Sample Amts Mix Design Verification Production Startup 1 per 4,000 tons or 2 every 5 paving days, whichever is greater 3 Pucks ≈ 14,100 grams (Per Split)
- 26. Verification Sample Tonnages 120 lb for each Coarse Agg 80 lb for each Fine Agg 10 lb for each Supplemental Fine Minimum of 50 lb from each RAP stockpile or 100 lb from the belt Total Agg: >460lbs-630lbs (1/4 Ton!) HMA: ≥250lbs ◦ Likely will need ≈650-1000lbs (1/4-1/2 Ton!)
- 27. Sample Locations QC samples from anywhere per CT125 QA TSR & Hamburg sampled from: ◦ Automatic sampling device at the plant ◦ Automatic sampling device at the truck ◦ Windrow All other QA HMA samples from: ◦ Automatic sampling device at the plant ◦ Automatic sampling device at the truck ◦ Windrow ◦ Mat behind the paver
- 29. Sample box attaches here Automatic Plant Samplers
- 32. On Site Storage? Too much volume of samples for retention Work with Caltrans to develop onsite storage with their lock for QA sample retention No More Lost Samples!
- 33. QC Nuclear Density Testing Required to perform QC Nuclear Gauge Density (CT375) for all non- minor jobs 3 per 250 tons or 3 per paving day (whichever is greater) Not used for acceptance, still using cores for acceptance
- 34. JMF Modifications Now need new JMF if changing binder source, LAS producer, or LAS dosage Can do a modification instead of full mix design instead Only test at OBC Caltrans verifies Hamburg, Air Voids, VMA, DP, & TSR (if desired) Each modification costs $2000
- 35. Verification Changes Must verify with plant set within 0.2% of OBC binder content Only two tries for free, additional tries are $3000
- 36. AMRL Accreditation Caltrans will require AMRL accreditation to move towards national standards and hopefully reduce workload on the Caltrans IA staff. Implementation will be with Superpave specs in July 2014 April 16, 2014 36
- 37. AMRL’s Role Accredits any of your labs that do testing for Caltrans Superpave mix designs Does not need to accredit basic labs (aka. only gradations, oil content, SE, etc.) Accredits lab & equipment, does not certify each individual technician Proficiency Sample ProgramApril 16, 2014 37
- 38. Caltrans’ IA Role Technician Proficiency Testing Technician Certification ◦ Still certify for HVEEM jobs ◦ Some test methods do not have equivalent AASHTO methods. Caltrans Laboratory Accreditation Manual Reference Sample Program April 16, 2014 38
- 39. AMRL Fees Application ($250 one time) Admin Fees ($725 annually) ◦ $350 Base Fee ◦ 15 methods*$25/method ◦ Applied after 1st year Basic Fees for 2 Scopes ($900 in assessment year) Individual Test Fees ($2960 in assessment year) Proficiency Samples ($1480 annually) TOTAL: ≈$4135 on a year
- 40. Out-of-Sequence Next tour: Oct 2014-June 2015 Can be 1.5x normal fee Group w/ other labs Fee may not apply to new laboratories, contact AMRL for estimate. April 16, 2014 40
Editor's Notes
- If you walk around this room today and ask a few of the people here why California is moving towards Superpave you will probably hear things like “We can’t get anyone to build a good stabilometer” or “because Caltrans likes making us buy a whole bunch of expensive equipment”. You may even hear one or two comments along the lines of “just to screw with us”. Although the conspiracy theorist in me may want to believe some of those people… let me explain what Superpave is going to give California.
- In 1987 Congress spent $150 million on a research program aimed to improve the performance, durability, safety, and efficiency of the Nation’s highway system, $53million of which was specifically dedicated to asphalt and developing a completely new approach to HMA mix design. They were tasked to investigate why some pavements perform well, while others do not, develop tests and specifications for materials that will out-perform and outlast the pavements being constructed then, and work with highway agencies and industry to have the new specifications put to use. So when you’re asked, Why is California going Superpave you can tell them because congress spent a ton of money to develop stronger, longer lasting roads and we’re jumping on the bandwagon.With that said, lets talk about what California’s version of Superpave is going to look like.
- Superpave Subtask group meetings are becoming Section 39 Meetings in April 2014, are tasked with examining possibility of QCQA but may not look anything like it does today as well as developing RSSs for section 39. If you are interested in participating, which I highly recommend, you can contact Tony Limas w/ Granite Construction or Pascal Mascaranas w/ Vulcan to get more information and be added to the list serve.
- -No more VFA Specification, replaced with range on VMA-VMA now has two values, mix design vs. production. Production is 1.0 lower.
- -Changes from Kneading Compactor to Gyratory mean changes to the volumetrics of your mix-With little changes to your current HVEEM mix your binder contents will likely go up, possibly considerably-With changes to gradation and components you may be able to get similar binder contents
- FAA not just when you have less than 10% natural sandChanged 1 Fractured Face from 90% to 95%Changed 2 Fractured Face from 75% to 90%
- So what does that mean for producers? If you’re a blast quarry probably not much, you may have to adjust a gradation or two but the real impact will come for sand and gravel deposits. If your FAA tests have been high in the past you may have to consider lowering the amount of natural sand in your mix or eliminating it all together. This may throw your plant off balance.With a higher fracture face requirement, some deposits may also need to look at alternate sources of rock or change how they are crushing their rock. Some may need to choke their feed better, others may need to install new pieces of equipment like impact crushers.
- If you are attending the Lab tour this afternoon you’ll be able to see the gyratory compactor in action.
- With Rubber still need to leave in mold for 90 minutes so increases the time slightly to about the same as HVEEM in total minutes.Stability test requires warming equipment, calibrating Stabilometer, running test.
- Needs electrical
- Because there is no longer a stability test, Rutting is being measured with HWT
- -PASS/FAIL
- -Previously no test for rutting. Had mixes that passed all requirements with flying colors but still rutted in the field.-May replace the TSR in the future as a faster test but not likely.
- -Different specifications for different binder grades, more passes for stiffer binders-Sometimes additional anti-strip can make the results better but sometimes they do not.-Binders that were modified using such processes as air-blowing or polyphosphoric acid (PPA) may perform worse with anti-strip additives. Polymers typically do not have this problem.
- Approx 9 hours for field sample
- TSR:Dry: 100 psi minWet: 70 psi minSubmit JMF without this testing, pull verification sample, we test first Hamburg & TSR, then tell Caltrans to move forward with verification if we pass internally.Only testing Hamburg & TSR once for mix design/verification
- NEW!
- 80 lbs!
- 192 lbs!
- 124 lbs!
- 3 gyro pucks 14,100 grams6 TSR pucks 21,600 grams4 Hamburg pucks 9200 grams2 rice samples 3000 grams2 oil content samples 3000 grams1 moisture content 500 grams Total sample 51400 grams or 113.32 lbs.
- TSR & Hamburg not pulled from Mat because of large amount of material
- Runs around $5k + labor
- HMA’s T-Rex Hydraulic Truck Sampler $16935
- Pavement Technology Inc.Cost?
- Spec meant to level the playing field and help ensure a quality, compacted mixTurn in results with other production test reports but is report only
- For pilot projects you do not have to be officially accredited but must be registered and awaiting proficiency samples/assessment
- Automatically enrolledTypically distributed once per yearTest multiple methods on each sample set. Must perform all offered test methods within the scope of your accreditation Approximately every 2-3 months.
- AMRL does not certify test methods by technician, only one person per lab needs to be capable. Caltrans wants each technician to show their proficiency (may grandfather people in)
- Basic Fees: For assessor costs associated with travel to the lab, assessment of general test apparatus, review of findings with lab staff, report preparation, and review of the quality system.$900 if assessment includes 1 or 2 scopes of testing (ex: Soil & Aggregate)$1585 for 3 or more scopes of testingIndividual Test Fees: For costs associated with the assessment of apparatus and observation of procedures associated with each of the test methodsFee is $140, $235, or $285 depending on testProficiency Testing: $160-$290 per test type
- Next tour is AFTER July 2014 deadline! Submit ASAP!If assessment is requested outside of the normal AMRL tour schedule there is additional fee of 1.5 times the normal laboratory assessment fee, plus extraordinary expenses (i.e. air travel, vehicle rental) may be applied.If you are already AMRL Accredited but just need Gyratory and Hamburg it is only about a 1 hr assessment.
- In 1769 a fortress and Franciscan mission was built in San Diego, CA in an effort to interact with the local natives.
- Over the next 54 years a footpath was created from San Diego to what we now know as Sonoma to connect 21 missions, outposts, forts, and pueblos built while exploring and settling the area.
- As the route was more and more traveled the footpath became a roadway wide enough to accommodate horses and wagons. Each stop on the route was at least a day apart and people traveled on dirt and naturally compacted travel ways with streams to ford and steep grades to scale.
- This route came to be known as El Camino Real.
- In 1908 the Ford Model T was introduced to the world and made automobiles affordable for many people, quickly starting the country’s conversion from animal-drawn carriages to motorized vehicles. Road maintenance on El Camino Real was still close to non-existent and even as cars began to travel the route, dirt was still the main road surface…unless it was wet…and then it became mud. It was not uncommon for teams of horses to have to rescue automobiles trapped in the mud.
- In 1912, just over 100 years ago, Caltrans began work on its first state highway construction contract, paving Highway 1, El Camino Real. In 1937, 25 years later, it was completed and served as an important tourist and commercial corridor, just as it does today.
- Although I’m not exactly sure of what type of paving was laid down on El Camino Real in the early 1900s, I can tell you that the common practice around that time period was to first dry the aggregate using shallow iron trays heated over open coal fires, then pour asphalt on top, and the operator would hand mix it. Quality of the mix was extremely dependent on the operator. Brooms, lutes, squeegees, and tampers were used to lay down the material by hand. The laborers did the majority of the work with lay down and spreading and if the job was really high tech they had a horse-drawn roller come in to compact afterwards.
- Around the 1920s construction methods started to quickly improve as asphalt plants began to take form but it would take hours to produce just one batch of asphalt. The first asphalt laid by a machine was put down back east using modified Portland cement concrete mechanical spreaders. Later, World War II took our engineers to war and when they returned they were experienced and educated in how to build good strong roads. Paving in California flourished.
- Over the years our plants have gotten larger and faster, we moved from hand mixing to mechanical mixing.
- We started testing our hot mixes for basic qualities like gradation and eventually moved to HVEEM testing.
- We started by using crude asphalt in our mixes and moved to petroleum based asphalts, then began grading them with Aged Residue specifications and now performance grades.
- California uses recycled materials in our roads instead of sending it to landfills, we use modifiers and warm mix technologies to make it easier to put down and longer lasting.
- Both our industry and government professionals work together to make our roads the best that they can be and our politicians make our infrastructure a priority.
- This Year. 2014. We are bidding and quite possibly starting to lay down California’s newest advancement, Superpave Hot mix, on Rte 1-El Camino Real. It has been 245 years since it began as a simple footpath to get from mission to mission and I for one am proud to see how far we have come but even more excited to see how far we can go.