scholarly journals Quantitative Analysis of the Blending Degree of Virgin and RAP Binders in Recycled Asphalt Mixtures with a High RAP Content

2018 ◽  
Vol 8 (12) ◽  
pp. 2668 ◽  
Author(s):  
Zhen Yang ◽  
Guoyi Zhuang ◽  
Xiaoshu Wei ◽  
Jintao Wei ◽  
Huayang Yu ◽  
...  
Keyword(s):  
Asphalt Pavement ◽  
Asphalt Mixtures ◽  
Reclaimed Asphalt Pavement ◽  
Structural Index ◽  
Comprehensive Understanding ◽  
Recycled Asphalt ◽  
Reclaimed Asphalt ◽  
Standard Curve ◽  
Study Results ◽  
Mineral Additives

Recycled asphalt mixtures (RAM), which are prepared by blending reclaimed asphalt pavement (RAP), virgin bitumen and mineral additives, provide a variety of advantages, including resource recycling, reductions in costs, and reduced negative environmental impacts. However, multiple agencies have expressed concerns about the utilization ratio of RAP; thus, a comprehensive understanding of the blending degree of virgin and RAP binders in RAM would be significantly helpful for promoting the application of RAP. This study aims to quantitatively analyze the blending degree of virgin and RAP binders in RAM with high RAP contents. Carboxyl-terminated butadiene acrylonitrile (CTBN) was utilized as a tracer to mark the virgin bitumen; in addition, Fourier transform infrared (FTIR) spectroscopy was used to develop the structural index of CTBN (ICTBN). By establishing the standard curve between ICTBN and the CTBN content, the blending degree of virgin and RAP binders at different locations within RAM can be determined quantitatively. The study results indicate that the RAP binder was completely blended with the virgin bitumen in the outer RAP layer. However, the blending degree decreased with an increase in the RAP depth, and the blending degree in the inner RAP layer was only approximately half that which was found in the case of complete blending.

scholarly journals Experimental study of recycled asphalt mixtures with high percentages of reclaimed asphalt pavement (RAP)

2011 ◽  
Vol 25 (3) ◽  
pp. 1289-1297 ◽  
Author(s):  
Gonzalo Valdés ◽  
Félix Pérez-Jiménez ◽  
Rodrigo Miró ◽  
Adriana Martínez ◽  
Ramón Botella
Keyword(s):  
Experimental Study ◽  
Asphalt Pavement ◽  
Asphalt Mixtures ◽  
Reclaimed Asphalt Pavement ◽  
Recycled Asphalt ◽  
Reclaimed Asphalt

scholarly journals The Influence of Mixing Conditions on the Macro-Scale Homogeneity of Asphalt Mixtures Blended with Reclaimed Asphalt Pavement (RAP)

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4137
Author(s):  
Quan Liu ◽  
Markus Oeser
Keyword(s):  
Mechanical Performance ◽  
Design Method ◽  
Asphalt Pavement ◽  
Mixing Time ◽  
Asphalt Mixtures ◽  
Reclaimed Asphalt Pavement ◽  
Mixing Conditions ◽  
Recycled Asphalt ◽  
Reclaimed Asphalt ◽  
Macro Scale

The homogeneity of asphalt mixtures blended with reclaimed asphalt pavement (RAP) is affected by many factors. Due to the complicated compositions of recycled asphalt mixtures, the inhomogeneity issue might cause insufficient mechanical properties of asphalt mixtures, even though a design method was appropriately adopted. Therefore, it is of great significance to study the influence of mixing conditions on the homogeneity of asphalt mixtures blended with RAP materials. This study focused on the macro-scale homogeneity of produced asphalt mixtures. Specifically, asphalt mixtures incorporated with 40% RAP content were produced in a laboratory using different mixing times and mixing temperatures. A multi-direction indirect tensile stiffness modulus (ITSM) test was proposed to quantify the homogeneity of produced samples. In addition, the digital image processing (DIP) method was used to identify the distribution of aggregates and RAP binder. The results indicated that the influence of mixing time on the macro-homogeneity of asphalt mixtures indicated that a longer mixing time was favorable for the material dispersion. The influence of mixing temperature mainly rested on two perspectives. One was that the temperature variation induced the change of binder viscosity. The other was that the temperature influences the diffusion process between RAP binder and new bitumen, which further affected the mechanical performance of produced asphalt mixtures.

scholarly journals Laboratory comparative assessment of warm and hot mixes Asphalt containing reclaimed Asphalt pavement

2020 ◽  
Vol 8 (2) ◽  
pp. 15-26
Author(s):  
Hasan H Joni ◽  
Aqeel Y M Alkhafaji
Keyword(s):  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Warm Mix Asphalt ◽  
Asphalt Mixtures ◽  
Reclaimed Asphalt Pavement ◽  
Moisture Resistance ◽  
Recycled Asphalt ◽  
Reclaimed Asphalt ◽  
Marshall Stability ◽  
The Impact

Warm mix Asphalt (WMA) could be mixed and used in paving at low temperatures to minimize the consumption of energy and the emissions of greenhouse gas. Recycled Asphalt pavement (RAP) could save Asphaltic cement and aggregate, which could achieve the better effects of recycling. However, both of the two WMA and RAP technologies have some deficiencies. Warm mix Asphalt and Reclaimed Asphalt pavement (WMA-RAP) technique may solve these issues and deficiencies when they are utilized together. This study investigated the implementations of WMA-RAP and its impacts on the performance of the Asphalt mixture. Under the framework of this study, four percentages of RAP (0%, 20%, 30%, and 40%) were added to the hot mix Asphalt (HMA) and WMA containing 4% Sasobit to study the impact of increasing RAP content on Marshall stability and moisture resistance of Asphalt mixtures. In summary, the Marshall stability of HMA and WMA mixtures is higher than the control mixtures. A small decrease in moisture resistance of both (HMA and WMA) containing RAP comparing to control mixtures Asphalt was observed, as shown by reduced the tensile strength ratios (TSR), but it is still much higher than the minimum of 80%.

scholarly journals The Challenges of Using Reclaimed Asphalt Pavement for New Asphalt Mixtures: A Review

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4052
Author(s):  
Giulia Tarsi ◽  
Piergiorgio Tataranni ◽  
Cesare Sangiorgi
Keyword(s):  
Management Practices ◽  
Asphalt Pavement ◽  
Asphalt Mixtures ◽  
Environmental Benefits ◽  
Reclaimed Asphalt Pavement ◽  
Recycled Asphalt ◽  
Reclaimed Asphalt ◽  
The Usa ◽  
Pavement Construction ◽  
A Minor

Reclaimed Asphalt Pavement (RAP) material mainly consists of removed asphalt concretes from existing infrastructures and, to a minor extent, of wasted or rejected mixes during the production processes. Being composed of two valuable non-renewable resources, i.e., aggregates and bituminous binder, its conscious use can ensure the sustainability of asphalt pavement construction. Thanks to the use of RAP material in new asphalt products, the USA saved 4.1 million tons of virgin binder and 78 million tons of virgin aggregates in 2018. Therefore, the use of RAP for the production of new asphalt formulations at the top of the recycling hierarchy is preferable instead of being down-cycled in low-value applications. The RAP material represents one of the most re-used construction products worldwide; in 2018, approximately 88% wt. and 72% wt. of RAP were used in USA and Europe, respectively, as aggregates for Hot, Warm and Cold Asphalt Mixtures and for unbound layers. Several studies have revealed positive responses of the recycled asphalt mixtures with high or very high content of RAP. However, the common practices of many countries still limit the RAP content to a 15–20% wt., on average, in the recycled asphalt mixes. The amount of RAP in asphalt concretes can be significantly increased by applying good management practices of the RAP, either processed or not, as well as novel production technologies and advanced mix design approaches. This manuscript aims to summarize the state-of-the-art of use of RAP aggregates in new asphalt mixtures. The economic and environmental benefits are also discussed.

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