Marshall method is used to calculate optimum asphalt contents by using 5 percentages of asphalt (3.5,4.0,4.5,5.0,5.5) and find stability ,flow,density and air voids for each specimen.
you must determine at which method you depend, there are two methods: first marshal and second superpave.
The optimum asphalt content to many engineers is the an asphalt content corresponding to an air voids ratio of 4%. However, it is more customarily, calculated as the average content of max stability, max unit weight and 4% air voids.
Please refer the following document It will help you to understand asphalt mix mixture design.
https://www.slideshare.net/PriyanshSingh1/hot-bituminous-mix-design
https://www.slideshare.net/PriyanshSingh1/marshall-mix-design-lab-report
Thank you. I also use Marshall method. I was interested what methods are being used in other countries.
Two method used to calculate the optimum percentage :-
By using Superpave and Marshall Method. Marshall method mostly used in my country .
Marshall method is used to calculate the optimum asphalt content . By prepare different percentage of bitumen as (4, 4.5 , 5, 5.5 , 6, 6.5 ).You must measure the Stability and Flow by Marshall device and calculate the Unit weight , Air void % (AV%) , Void in Mineral aggregate% (VMA%) and Voids filled with Bitumen %(VFB%) . You must draw the relationship between the percentage of bitumen and the (Stability, Flow, AV%, VMA% and VFB%).
From this Curves you must find the percentage of bitumen at maximum Stability and Unit weight and find the percentage of bitumen at 4% of AV%.
By using the average of three percentages of bitumen from this curves . you can find the optimum percentage of bitumen to asphalt mixtures.
by taking the average asphalt content of maximum ( stability )+ Max.(density)+ (air void=4)
The optimum bitumen content of bituminous mixtures is determined based on the average values that satisfy the sets of requirements for Marshall stability, Marshall flow, air voids, VMA, and VFB.
Reference:
Chapter Use of Recycled Aggregates in Road Pavement Applications
Dear Milan Marinković
There are two popular method to find optimum asphalt content (OAC) MArshall and Superpave. Marshall method is divided two way, first OAC is the average of asphalt content at Max stability, unit weight and 4% air voids in total mixture. Second OAC at 4% air voids in total mixture. Then for two way check stability, flow, voids in mineral aggregate, and voids in total mixture, should be in rang of the specification according to traffic level.
Superpave system OAC calculated at 4% air voids in total mixture, Then check voids in mineral aggregate, and voids filled with asphalt, should be in rang of the specification according to traffic level.
Based on two methods, we can find OAC
1. Marshall, from average asphalt content corresponding to max. stability, max. S.gravity and 4% Va
2. Superpave, from %Gmm design versus AC and 4% Va versus AC of total mix
- Badges
- Science topic
- Similar topics
- Publishing