Full description of the effect on environment when using 100% recycled asphalt can be found in the article: 

100% Recycled Hot Mix Asphalt: A Reviewand Analysis, Resources, Conservation and Recycling 


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
100 % recycling can provide true sustainability by closing the materials cycle and allowing to use the reclaimed asphalt in the same high value application as conventional asphalt. A reduction in energy use of 20 % can be achieved by switching to 100 % RAP asphalt, mostly due to embedded energy for production of constituent materials. Along with this 18 kg CO2eq emissions per ton of paved mixture can be saved. With respect to transportation distance, hauling of materials from 100 km distant site for 100 % RAP production would still generate less emissions than production of virgin mix at materials quarry. These environmental effects and implementation of innovative production process would greatly benefit the agencies that have applied certification systems for sustainable construction practices (LEED, Greenroads, etc.)

Full results of the research are summarized in the article. 

Emission calculations

The existing state of practice for 100% recycling does not allow for conclusive evidence on the long-term performance of such pavements. Thus the analysis is currently limited to unit inventory or cradle-to-gate analysis, which at the time time is the most reliable part of any life cycle calculation.

The developers of the different technologies also claim that emissions are similar to traditional asphalt plants. A mixture containing 25% sand, 70% crushed stone and 5% bitumen was used in the calculations as a representation of a typical virgin mix. 100% RAP mixture is considered having 12% recycling agent added from binder mass. It is also assumed that 100% RAP mix does not require any virgin binder addition. In practice this is often the case, since any lost binder is replaced by the addition of recycling agent. 

For simplicity, the transport distance was considered equal and consists of 50 km distance from quarry/RAP site to asphalt plant plus 50 km asphalt plant to paving site. The only variables in the process are energy use for production of constituent materials. The calculation results in Figure demonstrate that 18 kg of CO2 equivalent per ton of paved mixture can be saved by producing asphalt from 100 % reclaimed material.

The emission factors that were used in the calculation and full results can be found in the article.