Yuta HIRASAWA

Study on the Evaluation for HMA mixtures with RAP of below standard

Osamu TAKAHASHICTakeshi NAKAMURA

In the paving industry, the reuse of paved materials generated by pavement work is proceeding. The recycling rate of paved materials in our country is over 98% since 2000. In addition, the ratio of HMA mixtures with Reclaimed Asphalt Pavement hRAPh to the total amount of HMA mixtures produced also tends to increase, exceeding 75% as of 2008. In the paving industry, RAP can be an indispensable paving material. However, with the progress of recycling at a high level, an increase in RAP that is repeatedly used in the future is expected. Therefore, it is expected that the number of RAP of below  standard will increase in the future. In order to maintain the existing high-level recycling rate, there is an increasing need for performance evaluation for HMA mixtures with RAP of below standard. 
In this research, we compared and examined three indicators, "peeling resistance", "crack resistance", and "fatigue resistance", using RAP of above standard and below standard.  As a result of examination of each, the following knowledge was obtained.
In all of the blending conditions in these studies, an increase in breaking strength was observed due to an increase in the RAP blending ratio.
Based on the results, the RAP of below standard is generally inferior in deformation followability, and the mixture tends to become brittle as the blending amount in the RAP is increased. However, it was found that if the compounding amount is smaller, the performance corresponding to the current required performance can be obtained, and it is possible to obtain knowledge about the possibility of recycling of RAP of the below  standard.