scholarly journals A Method to Quantify Reclaimed Asphalt Pavement Binder Availability (Effective RAP Binder) in Recycled Asphalt Mixes

2019 ◽  
Vol 2673 (1) ◽  
pp. 205-216 ◽  
Author(s):  
Fawaz Kaseer ◽  
Edith Arámbula-Mercado ◽  
Amy Epps Martin
Keyword(s):  
Asphalt Pavement ◽  
Economic Benefits ◽  
Binder Content ◽  
Mix Design ◽  
Void Content ◽  
Reclaimed Asphalt Pavement ◽  
Asphalt Mixes ◽  
Reclaimed Asphalt ◽  
State Highway ◽  
Asphalt Mix

State highway agencies recognize the environmental and economic benefits of utilizing reclaimed asphalt pavement (RAP) in asphalt mixes. Currently, most agencies assume all of the RAP binder content is available for mix design purposes. However, the percentage of available or effective RAP binder in the asphalt mix is usually less than 100% and not quantified, which could yield dry asphalt mix with a high air void content, potentially leading to premature distress. The term available or effective RAP binder refers to the binder that is released from the RAP, becomes fluid, and blends with virgin binder under typical mixing temperatures. This study proposes a method to estimate the RAP binder availability factor (BAF) which can be used to adjust the virgin binder content in RAP mixes to ensure that the mix design optimum binder content is achieved. In this method, asphalt mixes were prepared so that, after mixing and conditioning, the RAP material can be separated from the virgin aggregate, which allows for a thorough evaluation of the extent of RAP binder availability in the asphalt mix. This method was verified in a preliminary experiment and then used to estimate the BAF of RAP from different sources, and a correlation between RAP BAF and the high temperature performance grade (PG) of each RAP source was established. Finally, factors affecting the RAP BAF were also evaluated such as mixing temperature, conditioning period, the use of recycling agents (or rejuvenators), and the method of adding the recycling agent to the mix.

Investigating Degree of Blending Between Reclaimed Asphalt Pavement and Virgin Binder Using Atomic Force Microscopy and Focused Ion Beam

2021 ◽  
pp. 036119812110184
Author(s):  
Mansour Solaimanian ◽  
Xuan Chen
Keyword(s):  
Atomic Force Microscopy ◽  
Focused Ion Beam ◽  
Asphalt Pavement ◽  
Ion Beam ◽  
Reclaimed Asphalt Pavement ◽  
Asphalt Mixes ◽  
Reclaimed Asphalt ◽  
Force Microscopy ◽  
State Highway ◽  
Atomic Force

Adding reclaimed asphalt pavement (RAP) into asphalt mixes is a common practice and has many merits such as reducing costs and emissions. In recent decades, many state highway agencies have embarked on investigating asphalt mixes with high RAP content. As the RAP content increases, understanding how well the RAP binder blends with virgin binder becomes more crucial. Lack of knowledge on how much of the residual RAP binder actively blends with virgin binder during production is one of the reasons preventing full exploitation of RAP materials. Obviously, the amount of aged RAP binder blending into virgin binder affects the properties of asphalt mixes. A study was undertaken to investigate the degree of blending, that is, the amount of RAP binder blended with virgin binder, through atomic force microscopy (AFM) and focused ion beam (FIB). The AFM measurements were conducted on both binder samples and RAP aggregate samples; the former consisted of extracted and recovered RAP binder, virgin binder, and blended binder, while the latter covered blended RAP aggregate and virgin binder samples. AFM measurements on binders indicated that blended RAP and virgin binder, at the blending zone between RAP and virgin binder, has moduli between that of pure RAP binder and pure virgin binder. AFM was also explored to investigate the degree of blending using RAP aggregate and virgin binder, but preparation of acceptable samples for such work was not possible, in spite of extensive work in preparation of such samples through mechanical polishing and FIB.

scholarly journals Rutting and moisture-induced damage potential of foamed warm mix asphalt (WMA) containing RAP

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Mohammad Ashiqur Rahman ◽  
Rouzbeh Ghabchi ◽  
Musharraf Zaman ◽  
Syed Ashik Ali
Keyword(s):  
Asphalt Pavement ◽  
Warm Mix Asphalt ◽  
Environmental Benefits ◽  
Reclaimed Asphalt Pavement ◽  
Chemical Additives ◽  
Flow Number ◽  
Damage Potential ◽  
Asphalt Mixes ◽  
Reclaimed Asphalt ◽  
Wheel Tracking

AbstractDespite significant economic and environmental benefits, performance of warm mix asphalt (WMA) containing reclaimed asphalt pavement (RAP) remains a matter of concern. Among the current WMA technologies, the plant foaming technique (called “foamed WMA” in this study) has gained the most attention, since it eliminates the need for chemical additives. In the present study, the laboratory performance, namely rutting and moisture-induced damage potential of foamed WMA containing RAP were evaluated and compared with those of similar hot mix asphalt (HMA) containing identical amount of RAP. Dynamic modulus, Hamburg wheel tracking (HWT) and flow number tests were performed to assess the rutting resistance of the mixes. Also, stripping inflection point from HWT tests and tensile strength ratio after AASHTO T 283 and moisture induced sensitivity test (MIST) conditioning were used to evaluate the moisture-induced damage of asphalt mixes. It was found that MIST conditioning effectively simulates the moisture-induced damage and can capture the propensity of asphalt mixes to moisture damage more distinctly compared to AASHTO T 283 method due to application of cyclic loadings. The foamed WMA was found to exhibit higher rutting and moisture-induced damage potential due to lower mixing and compaction temperatures compared to HMA. However, the increase in RAP content was found to reduce rutting and moisture-induced damage potential for WMA. Therefore, the lower stiffness of foamed WMA may be compensated with the addition of stiffer binder from RAP.

scholarly journals Evaluation performance of base course mixture containing reclaimed asphalt pavement (RAP)

2018 ◽  
Vol 162 ◽  
pp. 01037 ◽  
Author(s):  
Karim Al helo ◽  
Zaynab Qasim ◽  
Ahmed Majeed
Keyword(s):  
Asphalt Pavement ◽  
Stability Test ◽  
Reclaimed Asphalt Pavement ◽  
Test Results ◽  
Reclaimed Asphalt ◽  
Superpave Gyratory Compactor ◽  
Asphalt Mix ◽  
Asphalt Content ◽  
Base Course ◽  
Durability Performance

This paper presented the effect of addition of Reclaimed Asphalt Pavement (RAP) on performance of mixture with (20%, 30%, 40% and 50%) RAP as proportion of asphalt mix. To compare with virgin mixture marshall flow and stability test was used to evaluated durability performance with (0,1,3, and 7) days immersion and Wheel Truck test was used to evaluated the resist to rutting. The best gradation and optimum asphalt content was selected according to Superpave system. Superpave Gyratory Compactor (SGC) was used to compact mixture with 100-mm diameter. The test results indicated that addition of RAP to mixes showed significant increase on resistance of Durability and Rutting.

scholarly journals Effects of Asphalt Mix Design Properties on Pavement Performance: A Mechanistic Approach

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Ahmad M. Abu Abdo ◽  
S. J. Jung
Keyword(s):  
Asphalt Concrete ◽  
Asphalt Pavement ◽  
Binder Content ◽  
Mix Design ◽  
Pavement Performance ◽  
Dynamic Shear Modulus ◽  
Test Results ◽  
Analysis Software ◽  
Mechanistic Approach ◽  
Asphalt Mix

The main objective of this study was to investigate the effects of hot mix asphalt material properties on the performance of flexible pavements via mechanistic approach. 3D Move Analysis software was utilized to determine rutting and cracking distresses in an asphalt concrete (AC) layer. Fourteen different Superpave mixes were evaluated by utilizing results of the Dynamic Modulus (|E⁎|) Test and the Dynamic Shear Modulus (|G⁎|) Test. Results showed that with the increase of binder content, the tendency of rutting in AC layer increased. However, with the increase of binder content, the cracking of AC layer lessened. Furthermore, when different binder grades were evaluated, results showed that with the increase of the upper binder grade number, rutting decreased, and with the increase of the lower binder grade number, rutting increased. Furthermore, analysis showed that with the increase of the lower binder grade number, higher percent of bottom up cracks would result. As a result of the analysis, binder grade should not be solely considered for cracking in AC layer; binder content and aggregate structure play a big role. Finally, results illustrated that the mechanistic approach is a better tool to determine the performance of asphalt pavement than commonly used methods.

scholarly journals Mechanical performance assessment of half warm recycled asphalt mixes containing up to 100 % RAP

2017 ◽  
Vol 7 (080) ◽  
pp. 129 ◽  
Author(s):  
J. M. Lizárraga ◽  
A. Jiménez del Barco-Carrión ◽  
A. Ramírez ◽  
P. Díaz ◽  
F. Moreno-Navarro ◽  
...  
Keyword(s):  
Hot Mix Asphalt ◽  
Mechanical Performance ◽  
Asphalt Pavement ◽  
Reclaimed Asphalt Pavement ◽  
Recycled Asphalt ◽  
Stiffness Modulus ◽  
Asphalt Mixes ◽  
Reclaimed Asphalt ◽  
Second Stage ◽  
Asphalt Content

The use of Half Warm Mixes with high Reclaimed Asphalt content (HWMRA) has the potential to generate significant environmental advantages such as the reduction in consumption of natural resources and the emission of gases into the atmosphere. This paper therefore focuses on demonstrating the viability of using these types of mixes in wearing courses. For this purpose, an HWMRA with 70 % and 100 % Reclaimed Asphalt Pavement (RAP) and emulsion were designed in the laboratory. The performance of the mixes was then assessed and compared with that of conventional Hot Mix Asphalt. In a second stage, the mixes were manufactured in-plant, and laid and compacted in an Accelerated Pavement Test track. The cores were then extracted and tested for stiffness modulus and resistance to fatigue. The results from the tests conducted with both the laboratory specimens and the cores showed that the performance of HWMRA is comparable to that of HMA. These findings encourage greater confidence in promoting the use of these types of sustainable asphalt mixes.

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