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.

Effect of Mixing Time and Temperature on the Homogeneity of Asphalt Mixtures Containing Reclaimed Asphalt Pavement Material

2018 ◽  
Vol 2672 (28) ◽  
pp. 167-177 ◽  
Author(s):  
Jiantao Wu ◽  
Quan Liu ◽  
Yu Wang ◽  
Jun Chen ◽  
Dawei Wang ◽  
...  
Keyword(s):  
Color Image ◽  
Asphalt Pavement ◽  
Mixing Time ◽  
Asphalt Mixtures ◽  
Reclaimed Asphalt Pavement ◽  
Mixing Conditions ◽  
Stiffness Modulus ◽  
Reclaimed Asphalt ◽  
Average Value ◽  
Indirect Tensile

Laboratory-produced reclaimed asphalt pavement (RAP) material, new aggregate, and tinted new binder were mixed (RAP proportion: 40%) with 12 different combinations of mixing temperatures and times, based on which circular specimens of various thicknesses were fabricated and then subjected to multi-direction indirect tensile stiffness modulus (ITSM) testing and color image analysis. Statistical calculations including average value, coefficient of variation, standard deviation, and range were carried out to investigate the effects of different mixing conditions on the homogeneity of asphalt mixtures containing RAP. The results show that the deterioration of homogeneity of asphalt mixtures containing RAP was mainly caused by the asynchronous breaking of clusters. The mixing temperature was decisive in determining the resistance of clusters to breaking, and for mixing conditions chosen in this study, the resistance increases with the increase of mixing temperature. Short mixing time might lead to a phenomenon of “momentary homogeneity,” in which clusters were not broken and the blending degree between aged and new binder was low.

Mechanical performance of sustainable asphalt mixtures manufactured with copper slag and high percentages of reclaimed asphalt pavement

2021 ◽  
Vol 304 ◽  
pp. 124653
Author(s):  
Osvaldo Muñoz-Cáceres ◽  
Aitor C. Raposeiras ◽  
Diana Movilla-Quesada ◽  
Daniel Castro-Fresno ◽  
Manuel Lagos-Varas ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Asphalt Pavement ◽  
Copper Slag ◽  
Asphalt Mixtures ◽  
Reclaimed Asphalt Pavement ◽  
Reclaimed Asphalt

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 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.

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
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