Mix design

Mixture design of 100% recycled asphalt

For full description of the design principles and proposed mix design methodology see article: 
100% Recycled Hot Mix Asphalt: A Reviewand Analysis, Resources, Conservation and Recycling

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
 
The traditional mix design methodology, especially with respect to design of optimal binder content, has to be modified for totally recycled hot asphalt mixtures. The mix designer will have to make compromises when choosing how to process the reclaimed asphalt and what size fractions best satisfy the mixture gradation, binder content, mixture volumetric and performance-property requirements while efficiently utilizing the available material. Choice of recycling agent and its dose is another significant aspect.

Full description of the design principle can be found in the article. 


Mix design principle 

The aggregates are tested for required properties. The chosen RAP fractions are combined in an initial mixture composition. The binder is then extracted from the mixture to determine its properties and choose the necessary rejuvenator type and dose. The asphalt is mixed and compacted in laboratory to determine the required volumetric and performance-related properties. The steps are repeated by taking appropriate modification if correspondence to the specification requirements is not ensured at any stage. If due to properties of milled RAP (especially fines and binder content) the design of mixture with 100% RAP is not possible, virgin binder and aggregates can be added. However, care should be given to ensure sufficient blending of RAP and virgin binder as well as homogeneous coating of virgin and RAP aggregates.

Full description of each of these steps can be found in the article. 


Adjusting Binder Content

As an example, method for adjusting binder content are summarized, for other steps see article:  

  • Choose source RAP with higher binder content.
  • Increase fines content in the mixture, since they usually contain higher binder content [57, 58].
  • Choose less effective recycling agent. Organic products tend to be much more effective at a select dose compared to petroleum products [59, 46, 45].
  • Increase recycling agent dose. Care should be given to comply with the performance specification requirements, especially rutting.
  • Add virgin binder.

 


Comments