Warm Mix Asphalt Corey L. Pelletier Anderson Columbia Co., Inc. Director Asphalt Technologies Inc.

Transcription

1 Warm Mix Asphalt Corey L. Pelletier Anderson Columbia Co., Inc. Director Asphalt Technologies Inc.

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3 Benefits of WMA Energy Savings Reduced Emissions Improved Work Environment Improved Compactability Better Workability Long Haul Distances Better Temperature Uniformity Cold Weather Paving

4 Energy Savings with WMA Theoretical calculations indicate that a temperature reduction of 50 F will result in 11% fuel savings Fuel savings reported on various field trials average 23% Heat losses and inefficiencies in heating believed to account for increased savings over theoretical calculations

5 Selection of a WMA Technology Which WMA technology is best? It depends on various considerations/factors: How many tons of WMA do you expect to produce? Some processes have higher up front equipment cost, others have higher additive cost, included in every ton What sort of temperature reduction do you want?

6 Mix Design Drop In to an existing mix design Most additives work as a anti-strip To optimize your asphalt content it is better to design your mix as a warm mix. 0.1% to 0.2% lower asphalt content

7 Plant Modifications Plant burners need to be properly tuned for maximum fuel savings during WMA production Seal all air leaks in the baghouse Change drum flighting, slope, or air flow to increase baghouse temperature

8 WMA Production Concerns Reduced production rate Amperage on motors for drag slat conveyors, coaters, etc. Condensation in the baghouse Using RAP in WMA Alleviates Many Production Concerns

9 Production Properly preheat the baghouse Start plant at normal HMA production temperature Produce at least 5 loads or 100 tons at hot mix temperatures before switching to warm mix. This allows proper heating of plant components and roadway equipment. Slowly adjust the plant to target warm mix temperature

10 Production Why Are RAP and WMA a Good Match? Must superheat aggregate eliminating baghouse temperature concerns Less aging of virgin binder Improved coating Improved workability and compactability

11 Warm Mix Why isn't Warm Mix used more in Florida? Plants are designed to operate continuously. Changes take time and waste material. Dryer may require different flighting Different storage needed Burner may require different tuning Cost

12 Warm Mix Switching Between WMA and HMA Minimize changes Select one process Plan changes Start with HMA Switch to WMA

13 Cost Savings How can we reduce the cost of WMA? WMA is already approved by FDOT As an industry we need to meet with our local counties, commercial customers and municipalities to educate them about the benefits of WMA. Once you start WMA you need to stick with it to get the true cost savings it provides.

14 Density Consistent mat temperature gives more consistent density Consistent pay factors Able to back down on roller coverage's which can lead to increased production Eliminating a roller at times which reduces your labor and equipment cost

15 Thermal Segregation Associated with poor pavement performance. Resists adequate compaction even after aggressive rolling Higher permeability's due to lower density Lower shear strength Increased binder oxidation Reduced life of the road

16 Thermal Segregation

17 Thermal Segregation

18 I-10 Madison Mix Type: 12.5mm structural mix Mix Type: FC-5 Liquid: PG76-22 PMA WMA: 0.5% Evotherm M1 Haul Distance: 63 miles Average Density: 93.0% IRI Project

19 I-10 Description Production for the job started at temperatures of 320 F to warm up the equipment and was quickly dropped to 280 F for the remainder of the day. The haul distance was 63 miles, taking the trucks a little over an hour to reach the job and causing the mix to lose only 5 F during the haul. We used a Roadtec MTV and CAT AP1000D paver to place the mix. For compaction we used 2 CAT CB54 rollers in tandem to breakdown and another CAT roller to finish. Even though the rollers were restricted to static mode, core results averaged 93%. Once rolling patterns were established and density was not an issue we were able to eliminate one of the breakdown rollers which helped reduce cost. When we started the FC-5 we decided to do warm mix on the outside lanes and hot mix on the inside lanes. The reason for this was to determine if indeed we would get a better ride using warm mix with FC-5. The result was we did get a slightly better IRI in the warm mix lanes but not a significant difference.

20 Learner Outcomes There was little to no difference in the delivery, hauling, laydown, and placement of WMA from HMA Standard good construction practices are key to good performance Lower WMA temperatures may make hand work more difficult especially when using PMA

21 Conclusion There were no IRI ride deductions The overall IRI average was a 37 The bonus included an additional 3% bonus for not having any individual lots with an IRI above 55. The project was a success, thanks to everyone involved.

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30 Why Additive? Easy to Use Any mix plant No equipment to purchase or maintain Drop-in laboratory evaluations Lowest Temperatures Proven Performance

31 Case Studies Visit these sites for more information on WMA.

32 Questions?

33 Contact Information Corey L. Pelletier Anderson Columbia Co., Inc. Director Asphalt Technologies Inc. Office Cell