Production technologies

100% Recycled Hot-Mix Asphalt Production

Full description of the plants, cost analysis, mix design methodology, environmental analysis, and RAP management strategies can be found in the article: 
100% Recycled Hot Mix Asphalt: A Review and AnalysisResources, Conservation and Recycling 

SCIENTIFIC PUBLICATIONS

100% Recycled Hot Mix Asphalt: A Review and Analysis, (2014), Resour Conserv Recy 92: 230-245 http://goo.gl/rXFvbr  
Influence of Six Rejuvenators on the Performance Properties of Reclaimed Asphalt Pavement (RAP) binder and 100% recycled asphalt mixtures, (2014), Cons Build Mat 71: 538-550 https://sites.google.com/site/martinszaumanis/publications/publications-pdf-files/Zaumanis%20100%20recycled%20hot%20mix%20asphalt%20Res%20Cons%20Recycl.pdf?attredirects=0&d=1  
Determining optimum rejuvenator dose for Asphalt Recycling Based on Superpave Performance Grade Specifications, (2014), Cons Build Mat 69: 159-166 http://goo.gl/Vtlb3l  
Review of very high-content reclaimed asphalt use in plant-produced pavements: state of the art, (2015), Int J  Pavement Eng 16 (1): 39-55 https://www.researchgate.net/profile/Martins_Zaumanis/publication/261875706_Review_of_very_high-content_reclaimed_asphalt_use_in_plant-produced_pavements_state_of_the_art/links/54688c050cf2f5eb1804d9a9?ev=pub_int_doc_dl&origin=publication_detail&inViewer=true  
Evaluation of Different Recycling Agents for Restoring Aged asphalt Binder and Performance of 100% Recycled Asphalt, (2014), Mater Struct  https://sites.google.com/site/martinszaumanis/publications/publications-pdf-files/Zaumanis%20Recycling%20agents%20Materials%26Structures.pdf?attredirects=0&d=1  
Rheological, microscopic, and chemical characterization of the rejuvenating effect on asphalt binders, (2014), Fuel 135: 162-171 https://sites.google.com/site/martinszaumanis/publications/publications-pdf-files/Zaumanis%20Rejuvenation%20characterization%20Fuel.pdf?attredirects=0&d=1
Evaluation of Rejuvenator's Effectiveness with Conventional Mix Testing for 100% Reclaimed Asphalt Pavement Mixtures, (2013) Transp Res Rec 2370 (1): 17-25  https://sites.google.com/site/martinszaumanis/publications/publications-pdf-files/TRR%202013.pdf?attredirects=0&d=1  
Finite element modeling of rejuvenator diffusion in RAP binder film – simulation of plant mixing process, RILEM symposium 2013, Stockholm, Sweden, 06.12-14.2013    
Low temperature properties of 100% reclaimed asphalt pavement mixtures, 5th European Asphalt Technology Association, Braunschweig, Germany, 06.03-05.2013       
Use of Rejuvenators for Production of Sustainable High Content RAP Hot Mix Asphalt, 28th International Baltic Road Conference, Vilnius, Lithuania, 08.26-28.2013
Interactive presentation of Phase I results and research plans
 






















TECHNOLOGIES FOR 100% RECYCLING



There are multiple technologies readily available for 100% hot mix asphalt recycling. Many of them are listed here along with links to the websites of the manufacturers and short descriptions.
  
Detailed description of some of the technologies as well as usage statistics can be found in the article. The paper also describes 100% recycled asphalt mixture design, RAP management practices and the potential economic as well as environmental benefits from 100% recycling. 

If you happen to know more resources or have been a part of 100% recycling project, please contact me through jeckabs@gmail.com








RAP Technologies

Location: Queens, New York City
  

RAP Technologies plant in NYC

RAP Technologies, LLC (www.RAPTech.us) approached producing 100% RAP hot mix as an air pollution challenge rather than attempting to reinvent established manufacturing processes. The “All RAP Process” technology uses convention hot mix asphalt plant components and a special blue smoke filtration system. Since first producing mix in 2001-2004 demonstration project with NYCDOT, the RAPTech process has been licensed to Green Asphalt, Long Island City, NY and produces 100,000 tons of 100% RAP mixes annually for private paving contractors. Streets paved in 2001 are still in service and provide living record of the durability of 100% RAP mixes on secondary streets. Read more...

100% RAP paving in NYC


100% RAP is produced and placed at temporary city street pavements, parking lots, industrial areas etc. Recently a demonstration project of 100% RAP along with conventional asphalt has been paved by the city DOT in Jewel Avenue & 147th Street in Kew Garden Hills, Queens. Long term performance can be evaluated by visiting 78th street that was paved in 2001.








HERA System

Website: http://en.volkerwessels.com/en/projects/detail/hera-system
Location: Rotterdam, The Netherlands

HERA System Illustration


From producers home page:
The HERA System is the result of years of research into cleaner, better and cheaper asphalt production and recycling. “This is something we can be very proud of,” says Chairman of VolkerWessels’ Management Board, Gerard van de Aast. “The HERA System showcases our innovative strength and helps create a cleaner environment.” 

Asphalt is normally produced and recycled by directly heating the raw materials. The HERA System works completely different, by applying indirect heat. The result:
*A higher percentage of reuse of old asphalt
*Much lower emissions of harmful gases
*Virtually no odours
*Asphalt can be recycled an additional 3 to 5 times
*Asphalt lasts longer
*Cost savings; fewer (primary) raw materials and lower fuel costs



SMART Pave


Website: http://www.smartpavesystem.com/index.html

From producers home page:
Step one

The reclaimed asphalt pavement (RAP) is analyzed for composition qualities including binder and gradations. 
The binder is analyzed for PG properties. Regional Properties may be used in this analysis. Generally, a very small percentage of rejuvenator agent is introduced to adjust the binder to the desired PG grade. This also provides full replenishment of any oxidized asphaltenes, returning the asphalt cement to its original characteristics. This is usually about .5% (1/2 of 1%) of the HMA produced.
If the existing milled composition comes from a known source and meets specification gradation requirements “as is”, no further RAP pre-processing is necessary.Steps Two and Three would not be required and Step Four would be next - heating the material.
Step Two
If the RAP comes from varied sources, the RAP stockpile is screened and "fractionated" to return the RAP to original gradations. The various gradated RAP products are then fed into their respective cold feed bins.
Step Three
Depending on gradation analysis, the feed bins will introduce the gradated RAP at the correct feed rate. If due to specification gradations, any virgin aggregates adjustment is needed, the virgin aggregates are introduced along with the gradated RAP in the correct proportion via a multi-bin metered cold feed system.
Step Four
An indirectly heated (specifically designed for 100% RAP) drum plant processor is used for full heating of 100% recycled asphalt or any recycled-virgin blend mix.
Step Five
Once material processing has been completed, the fully heated recycled HMA is conveyed into silo storage, awaiting discharge into trucks for transport to the jobsite.
Step Six
At the jobsite, the recycled hot-mix asphalt is transferred to the roadway by the pavement lay down crew. The 100% recycled asphalt pavement actually results in "equal to or better" quality and performance than HMA made from new virgin materials and is handled in the same manner.
A key part of the Smart Pave System is RAP stockpile discipline. Control of your RAP source and inventory will pay for itself many times over. A properly worked RAP stockpile along with screening/fractionating will create a very uniform composite mix, usually more consistent than virgin material from a quarry. Screening of RAP may be necessary to eliminate unwanted tramp material, but crushing should be avoided if possible as a) it may add substantial unnecessary cost, and b) it creates added fines to the mix – an undesirable attribute that may actually place your valuable RAP out of specification bands. Generally speaking, RAP milled from highways and roadways with upward cut milling heads will generally stay within 10% of original specifications.


BAB Belag AG in Switzerland, Birmenstorf operates Amman “Uniglobe 200” plant with “RAH100” reclaimed asphalt dryer drum. The plant utilizes a unique dryer designed by Amman to allow RAP heating without direct contact to flame.

The drum is installed on top of the tower to ensure gravity-driven handling of the hot RAP. A counter flow dryer with two phase drum is used. The material heating and drying phase of the drum rotates, while the combustion chamber is static. The RAP is heated with hot air and is discharged before getting in contact with the flame. Thus it does not get in direct contact with flame, reducing emissions and limiting RAP binder aging.

Usual RAP discharge temperature is 165-180°C. The air recirculation system improves drying efficiency in comparison to conventional systems by 10%, ensures low oxygen content to further reduce aging and reduces emissions (6). After discharge gravity drives the material into hot storage silo which has a capacity of 28t. The RAP is further released to the weight hopper and asphalt pugmill of 3t capacity. The recycling agent and virgin binder, if any, is added in the pugmill and mixed together with RAP for 30 to 40 seconds.











Alex Sin Manufacturing

Location: Jurupa Valley, California. 
Owner: Pavement Recycling Systems

Alex Sin 100% RAP plant

A drum dryer without direct exposure of RAP to flame is used in the „Alex-Sin Manufacturing” plant that is capable of 100% RAP production. Seven burners are located in a heating chamber and perpendicularly heat rotating drum dryer shell from exterior as demonstrated in Figure 6. Ray shields (46cm wide) are located on the drum perpendicular to flames to prevent drum from heating unevenly. The heat from drum by conduction transfers to the RAP. Front third of the drum is constructed of aluminum while the rear two-thirds are made of 310 stainless steel. Hot combustion gasses flow through the heating chamber and enter the drum at 680°C to move in the opposite direction to the material flow. In addition breech
ports are placed inside the drum to introduce hot air at drum center. Fins are welded on the exterior of the drum at 45° angle to aid at churning of air and work as secondary thermal mass conductors. The burner output is controlled by three infrared readers that are set to maintain the inner drum surface temperature between 480 to 540°C. The burners operate between 650 and 900°C and, based on temperature readings, are typically set to three different output levels, ranging from 100% at the entrance of materials to 50% (or less) of maximum output at the exit of the drum. Fuel use of 3.8 to 5.7 liters per ton of mixture produced has been recorded at ambient temperatures ranging from 10 to 30°C. The final mixture temperature can be adjusted as required and the maximum stack temperature is 80°C.

Any virgin binder or recycling agent can be added at the mixing zone at the end of the drum though a pipe that penetrates the rear wall. 




HyRAP

Locatoin: Fort Wayne, Indianna

100% RAP in Fort Wayne


From producers home page: 
Fort Wayne, IN (June 22, 2011) Brooks Construction Company, Inc. held a grand opening today to celebrate its new state-of-the-art facility and introduce HyRAP 100% recycled asphalt paving material. 
HyRAP can be produced without any additional mining of aggregates and without the usage of virgin aggregate, thereby, reducing petroleum consumption and reliance on foreign oil.

Future HyRAP facilities can be located in close proximity to jobsites because there is no need to be near virgin aggregate material sources or quarries. This significantly reduces the costs as well as the emissions associated with trucking in our industry.



RATech

Website: http://www.e-mak.com/en/products/ratech.asp?SectionID=87
Plant producer: E-MAK

RAP is fed into triangular recycling drier using vertical elevator where it is indirectly heated by hot air of 200-400°C and directly exposed to 120-200°C as illustrated. This reduced temperature compared to conventional plants helps limiting the aging of RAP binder and lowers the emissions. A controllable speed spiral conveyor is spreading the RAP slowly between the drier’s plates where it is heated through the hot surfaces of the channel and the driving plate surfaces to desired temperature. The driving plates are designed to limit sticking of RAP and reduce segregation. After heating the RAP is released to RATech mixer via weighing unit. Any recycling additives or virgin bitumen are added in at this stage and 45 second mixing time is suggested. The hot RAP is kept in a heated silo until ready for discharge. The production capacity of the plant significantly varies based on the RAP moisture content. It will drop from 180t/h for 1% moisture to around 80t/h for 5% moisture content


The hot air that is used to bring the RAP to the desired process temperature is obtained from heat generator, which consists of combustion space and burner (Figure). The released hot air from the burner is mixed with controlled amount of cold air and fed into circulation channels of triangle drier at the required temperature. The temperature, flow rate, speed, and pressure of the circulating air is controlled automatically. The temperature at air filter has dropped to 90-95°C. 


Benninghoven

Website: http://www.benninghoven.com/index.php?option=com_content&task=view&id=34&Itemid=54

From producers home page:
Benninghoven achieves 100% Recycling through a separate, uniflow large volume drying drum equipped with a special burner. The design of the drier internals preclude direct contact between the flame and reclaimed material. After heating, the processed asphalt is stored in an insulated buffer silo from where it is batch weighed and introduced to the mixer as required.


Location: Carrollton, Ohio

RapSaver is a preheating system comprised of a continuously fed sealed conductive heating systems that allows cold wet RAP to be heated and dried using a slow moving hollow screw heating auger and heated trough.


Bagela Portable Asphalt Recycler



Bagela Asphalt Recycler

From distributors home page: 

1. Asphalt waste material (broken chunk, milling or RAP) are loaded mechanically into the hopper.

2. Hopper feeds material to drum, where indirect heat and tumbling action work to breakdown (recycle) the material into a viable hot mix.

3. Recycled asphalt hot mix is available within approximately 15 minutes.

4. The recycled hot mix can be discharged directly onto the repair site, or if statically positioned directly into a hot box or patching truck.

5. Recycled hot mix is continuously available until the repair is complete.

6. Normal techniques are used to place and compact the hot mix asphalt.

*100% Recycled Hot Mix Asphalt
*Portable On-Site Production
*Minimizes Disruption to Business and Commercial Facilities
*24/7/365 ALL-SEASON Operation
*Proven German Technology Now Available in Canada
*Not Like Any Other Asphalt Recycling Machine Previously Available
*Eliminates Cold Patching
*Ideal for all Asphalt Maintenance and New Construction
*The Bagela System’s Recycled Asphalt Meets or Exceeds Current Specs



RSL Asphalt Recycling Machines

producer website: http://www.rslplant.co.uk/

US representative: http://www.asphaltrecycling.com/
From producers website: 

*Up to 50% cost savings on base and 
surface course
*15+ tons per hour production rate
*Self-temperature regulating
*Paver performance & workability never before seen in recycling
*A fully sustainable solution
*Huge CO2 and odour reduction
*Self-cleaning
*Produce base, binder and surface course material
*Lower recycling temperatures reducing fuel consumption



Astec RAP King

producer website: http://www.astecinc.com
 
From producers website:
  • Dryer is a hot-oil tube type rotary drum
  • RAP flows across internal hot-oil filled tubes as the drum rotates
  • Heating of RAP is done without direct flame or hot gas exposure
  • Air is displaced from the drum by steam produced in the drying process. Drying is accomplished in a near oxygen-free atmosphere thereby minimizing oxidation of the liquid asphalt held in the RAP
  • Steam and any hydrocarbons produced in the drying are ducted to the combustion chamber of the hot-oil heater where hydrocarbons are destroyed
  • The drum drive is equipped with a variable frequency drive to control heat transfer rate and RAP retention time
  • The drum and its heating tubes are equipped with self-cleaning provisions
  • Multiple RAP entry points are not required
  • Tube wear is minimal due to slow rational speed and by the fact that RAP is held in the tube bundle and is not dropped or showered as is the case with traditional dryers

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