Use of High Contents of Reclaimed Asphalt (RAP) in Hot Mix Asphalt (HMA) Pavements

Transcription

1 Use of High Contents of Reclaimed Asphalt (RAP) in Hot Mix Asphalt (HMA) Pavements Presenters: Sumon Roy 1 and Badrul Ahsan 1 Faculty Mentor: Zahid Hossain 2, Ph.D., P.E. 1 Graduate Teaching/Research Assistant 2 Associate Professor of Civil Engineering Arkansas State University July 20, 2017

2 Presentation Outline Introduction Background of the Study Objectives Materials and Methodology Results and Discussions Conclusions and Recommendations

3 Introduction Over 90% of U.S. highways and roads are constructed with hot mix asphalt (HMA). According to the Federal Highway Administration s (FHWA) recycled materials policy: The same materials used to build the original highway system can be re-used to repair, reconstruct, and maintain them. Where appropriate, recycling of aggregates and other highway construction materials makes sound economic, environmental, and engineering sense. HMA producers use reclaimed asphalt pavement (RAP) as a valuable component in HMA Growing interest in increasing the RAP content in HMA pavements

4 Background of the Study Existing asphalt pavement materials removed (resurfacing, rehabilitation, or reconstruction) and processed RAP FHWA and the U.S. Environmental Protection Agency (1990) estimated: More than 90 million tons of asphalt pavements were reclaimed Over 80 percent of RAP was recycled RAP in recycled asphalt paving: Replacement of expensive aggregate and virgin asphalt binder Granular base or subbase, stabilized base aggregate Embankment or fill material RAP in HMA pavements: MEPDG tool for analyzing sensitivity parameters

5 Objectives Perform MEPDG-based analysis of HMA pavements with RAP Estimation of the rutting and fatigue cracking based on Level 1 inputs of asphalt binder and mixes Perform sensitivity analysis of aforementioned distresses of HMA with different amounts of RAP and layer thicknesses with respect to a typical pavement section

6 Why RAP? Affordable, environmentally sound, and sustainable Reduction in material costs, labor costs, and energy costs Reduces the consumption of our natural resource supply Decrease the amount of waste in landfill Encourages the appropriate widespread use of secondary materials Provides long-term performance which is equal to or better than virgin mix Increased use of RAP as a percentage of the total asphalt mix can significantly reduce greenhouse gas emissions by eliminating the significant fuel consumption required to acquire and process raw materials for virgin mix

7 Methodology and Materials The AASHTO Pavement ME Design software version was used for MEPDG analysis of all pavements. The material properties data and lab test data were collected from the Implementation of MEPDG for asphalt pavements with RAP report (Hossain et al. 2014). Considered Oklahoma S3 (Base course) and S4 (Surface course) mixes 6 inch surface (S4) and 9 inch base (S3) was considered over 12 inch nonstabilized base in this study.

8 Methodology and Materials (Cont..) Table 1: Aggregates and RAP1 Gradations (Percent Passing)

9 Methodology and Materials (Cont..) Table 2: Summary of Mix Gradation for S3-25 and S3-40 of RAP1 Mixes

10 Methodology and Materials (Cont..) Table 3: Summary of Aggregates Properties and Volumetric properties of S3-25 and S3-40 of RAP1 Mixes

11 Methodology and Materials (Cont..) Table 4: Summary of Mix Gradation Volumetric properties for S4-0 and S4-10 of RAP1 Mixes

12 Methodology and Materials (Cont..) Table 5: Summary of Aggregates Properties and Volumetric properties of S4-0 and S4-10 of RAP1 Mixes

13 Methodology and Materials (Cont..) Asphalt Binder Input Parameters

14 Methodology and Materials (Cont..) Asphalt Mixes Input Parameters

15 Methodology and Materials (Cont..) Asphalt Mixes Input Parameters

16 Results and Discussions Effect on Rut Depth Increased amount of RAP percentage with virgin binder reduces rut depth S4-25-S3-40 section shows 14% lower rut than S4-0-S3-25 Figure 1: Rut Depth (in) of pavements with various RAP percentage

17 IRI Value IRI value is significantly reduced with the high RAP percentage S4-25-S3-40 shows 2.3% lower IRI than S4-0-S3-25 Figure 2: IRI Value of pavements with various RAP percentage

18 Fatigue Cracking Fatigue cracking increases with the increase of RAP content in base course but opposite phenomenon occurs in surface course S4-25-S3-40 shows 11.1% higher bottom up cracking than S4-0-S3-25 Figure 3: Fatigue Cracking of pavements with various RAP percentage

19 Thermal Cracking RAP has no influence over thermal cracking of binders Figure 4: Thermal Cracking of pavements with various RAP percentage

20 Creep Compliance Figure 5: Creep Compliance vs. Loading with various RAP percentage Increase of RAP percentage in base course and surface course shows lower creep compliance with loading time

21 Conclusions and Recommendations High percentage of RAP in all mixes : Reduced: Rut depth, Asphalt Concrete (AC) bottom-up fatigue cracking, and IRI values Increased: (AC) top-down fatigue cracking is significantly higher Findings of this study are helpful to pavement professionals To analyze HMA mixes using the MEPDG tool Usage of RAP as substitute to virgin materials in the production of HMA: Reduces the use of virgin aggregate Decrease the amount of virgin asphalt binder Optimizes the use of natural resources Sustains the asphalt pavement industry.

22 Thank you!!! Question/Comment?