Approach for Determination of Maximum Reclaimed Asphalt Pavement Content in Polymer-Modified Asphalt Mixture

Author(s):  
Bongsuk Park ◽  
Jian Zou ◽  
Reynaldo Roque ◽  
George Lopp ◽  
Zhengyu Wu

Reclaimed asphalt pavement (RAP), commonly generated from the millings of damaged roads, contains recyclable asphalt and aggregate. Polymer-modified asphalt (PMA) binders have had proven success in mitigating rutting and cracking in asphalt pavements. However, benefits associated with PMA binder may be reduced by aged and more brittle RAP binder. Currently, the maximum usage of RAP in PMA mixture is limited to 10–20% by several Departments of Transportation in the United States. Other than maximum RAP content, no criterion related to RAP characteristics is used to limit RAP usage in PMA mixture. Recent studies showed RAP binder stiffness and RAP aggregate gradation appeared to be important characteristics related to cracking performance of PMA mixture containing RAP. Therefore, this research focused on determining maximum allowable RAP content in PMA mixture for individual RAP sources based on key RAP characteristics identified, that is, RAP stiffness and RAP fineness. Interstitial component direct tension (ICDT) test was conducted to determine fracture energy for interstitial component (i.e., the fine portion of PMA mixture containing RAP), which is known to be correlated well with the fracture energy of the corresponding mixture. Results showed introduction of coarser and less stiff RAP generally resulted in greater fracture energy, which allowed up to 40% RAP usage in PMA mixture. Integration of key RAP characteristics identified and the results of ICDT test provide a systematic approach for determination of maximum RAP content in PMA mixtures. Further research is recommended to evaluate additional RAP sources to verify the proposed approach.

2021 ◽  
Vol 2 (2) ◽  
pp. 27-34
Author(s):  
Tiza Michael

This study reviews relevant literature on the characterization of reclaimed asphalt pavement (RAP) and its interaction with polymer modified asphalt(PMA). The study on fatigue cracking indicates that several indexes of binder performance usually decreased the tolerance to cracking of the Polymer Modified Asphalt (PMA). In another perspective, RAP binding rigidity affects the PMA binder tolerance to fatigue. The greater the rigidity of the RAP binder, the more fatigue strength the binders would provide. In addition, several researchers have demonstrated that the quality of RAP binder decreased the elastomeric response worth. It was generally found that the RAP binder effect on the PMA binder is similar to the unmodified binder effect. The resistance to rutting in the PMA binder improves and at the same time, fatigue cracking and thermal cracking are adequately minimized. Moreover, several researchers have shown that the inclusion of a RAP lowers elastomeric efficiency. In summary, RAP binding stiffness and gradation are essential features for PMA-mix designs. The review further illustrates that during the process of RAP binder characterization, the mortar testing process without the use of binder extraction is more effective than the conventional method. Also, the best measure for the evaluation of the fatigue cracking efficiency of RAP containing PMA blends does not seem to have gained any consensus among researchers as several researchers seem to have varying conclusions. Literature on Life Cycle Analysis of RAP has also been reviewed and presented.


2021 ◽  
Vol 28 (3) ◽  
pp. 349-358
Author(s):  
Thopan Andhika Putra ◽  
Bambang Sugeng Subagio ◽  
Eri Susanto Hariyadi

Abstract One way to be developed to overcome challenges in providing flexible pavement materials is to apply the green roads principle by reusing some or all of the old road pavement material or Reclaimed Asphalt Pavement (RAP) as a material for new road pavement, which if reused will affect the performance of the mixture, such as decreasing the level of durability and premature pavement damage, so an effort must be made to improve the performance of the recycled material, namely by adding full extracted Asbuton and rejuvenating materials. The RAP material was obtained from scratching the asphalt of the Jagorawi Toll Road. The mixture used was asphalt concrete-binder course (AC-BC) layer using 30%, 40%, and 50% RAP material, using full extracted Asbuton at 6%, and Nichireki rejuvenating material. Then, on mixtures with RAP material, Marshall Test, Resilient Modulus test with UMATTA, and resistance to fatigue with four points loading test with strain control were conducted. The use of RAP material with modified asphalt in the form of an addition of full extracted Asbuton into the Pen 60/70 Asphalt can increase the asphalt stiffness. Marshall test results showed that a mixture with 6% full extracted asbuton content and 0% RAP material content (A6RAP0) gave the highest stability value. The results of the Resilient Modulus test showed that the mixture with 6% full extracted asbuton content and 50% RAP material content (A6RAP50) gave a high Resilient Modulus value at a test temperature of 45oC. The results of the fatigue resistance test showed that the mixture with 6% full extracted asbuton content and 50% RAP material content (A6RAP50) at a strain level of 300 µε gave the longest fatigue life. Keywords: Reclaimed asphalt pavement (RAP), full extracted asbuton, asphalt concrete -binder course, modified asphalt, resilient modulus, fatigue life. Abstrak Salah satu cara dikembangkan untuk mengatasi tantangan dalam penyediaan material perkerasan lentur adalah menerapkan prinsip greenroads dengan memanfaatkan kembali sebagian atau keseluruhan material perkerasan jalan lama atau Reclaimed Asphalt Pavement (RAP) sebagai material untuk perkerasan jalan yang baru, dimana jika digunakan kembali akan mempengaruhi kinerja dari campuran seperti penurunan tingkat durabilitas dan kerusakan dini perkerasan, sehingga harus dilakukan suatu upaya untuk memperbaiki kinerja dari material daur ulang tersebut, yaitu dengan penambahan Asbuton murni dan bahan peremaja. Material RAP didapatkan dari hasil garukan aspal Jalan Tol Jagorawi. Campuran yang dipakai adalah Laston Lapis AC-BC menggunakan kadar material RAP sebanyak 30%, 40%, dan 50%, dengan penggunaan Asbuton murni sebesar 6%, serta bahan peremaja Nichireki, dan kemudian selanjutnya pada campuran dengan penggunaan material RAP dilakukan pengujian Marshall, Modulus Resilien dengan alat UMATTA dan ketahanan terhadap kelelahan (fatigue) metode four points loading test dengan kontrol regangan. Penggunaan material RAP dengan aspal modifkasi berupa penambahan Asbuton murni kedalam Aspal Shell Pen 60/70 dapat meningkatkan kekakuan aspal. Hasil pengujian Marshall menunjukkan campuran dengan kadar Asbuton murni 6% dan kadar material RAP 0% (A6RAP0) memberikan nilai stabilitas tertinggi. Hasil pengujian Modulus Resilien menunjukkan campuran campuran dengan kadar Asbuton murni 6% dan kadar material RAP 50% (A6RAP50) memberikan nilai Modulus Resilien yang tinggi pada temperatur pengujian 45oC. Hasil pengujian ketahanan terhadap kelelahan menunjukkan campuran dengan kadar Asbuton murni 6% dan kadar material RAP 50% (A6RAP50) pada regangan 300 µε memberikan umur kelelahan yang paling panjang. Kata-kata kunci: Reclaimed asphalt pavement (RAP), Asbuton murni, laston lapis antara, aspal modifikasi,  modulus resilien, umur kelelahan.  


Author(s):  
Zhou Zhou ◽  
Xingyu Gu ◽  
Fujian Ni ◽  
Qiang Li ◽  
Xiang Ma

The cracking resistance of asphalt concrete (AC) that contains reclaimed asphalt pavement (RAP) was evaluated in this study with a fracture energy approach. Monotonic and cyclic semicircular bending (SCB) tests were performed with the digital image correlation to correlate crack length with fracture energy. Five types of AC that contained various RAP content (0%, 15%, 30%, 40%, 50%) were evaluated at two intermediate temperatures (15°C and 25°C). On the basis of the relationship between fracture energy and crack extension length, several performance indicators for cracking were proposed: fracture energy and crack initiation energy in monotonic and cyclic SCB tests, an energy cumulative rate in monotonic SCB tests, a fatigue accumulation index (FAI), a fracture energy index, and the slope of the crack steady propagation stage (SOCSP) in cyclic SCB tests. The effects of the RAP content on these indicators were investigated. It was observed from the test results that RAP reduced the fracture energy and crack initiation energy in the monotonic and the cyclic SCB tests. RAP led to a lower energy cumulative rate than an AC mix without RAP in the monotonic SCB tests. Similarly, the FAI and SOCSP values were found to decrease with an increase in RAP content in the cyclic SCB tests. These results indicated that, in general, the addition of RAP reduced the cracking resistance at intermediate temperatures.


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