scholarly journals Characterization of Sustainable Asphalt Mixtures Containing High Reclaimed Asphalt and Steel Slag

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4938
Author(s):  
Panos Georgiou ◽  
Andreas Loizos
Keyword(s):  
High Performance ◽  
Steel Slag ◽  
Organic Additive ◽  
Asphalt Mixtures ◽  
Economic Sectors ◽  
Recycled Asphalt ◽  
Moisture Susceptibility ◽  
Reclaimed Asphalt ◽  
Circular Model ◽  
Effective Option

Policymakers are implementing the transition to a circular model in all economic sectors to drastically mitigate the effects of climate change. In this regard, the producers of paving products should promote the reuse and recycling of solid waste in the design of sustainable asphalt materials. This study evaluated the performance-based properties of three highly recycled mixtures for wearing courses of asphalt pavements containing steel slag and varying amounts (25, 40, and 50%) of fractionated reclaimed asphalt (RA). In addition, the mixtures incorporated a warm mix asphalt (WMA) organic additive to lower production temperatures compared to a reference hot mix asphalt (HMA). Based on the experimental results, the warm recycled asphalt mixtures show equivalent or better performance compared to HMA in terms of moisture susceptibility, stiffness, rutting and fracture resistance, and surface macrotexture. Therefore, the combined incorporation of RA and steel slag with WMA was proven to be an effective option in designing environmentally friendly and high-performance wearing course mixtures.

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.

High-Performance Thin-Lift Overlays with High Reclaimed Asphalt Pavement Content and Warm-Mix Asphalt Technology

2012 ◽  
Vol 2293 (1) ◽  
pp. 18-28 ◽  
Author(s):  
Walaa S. Mogawer ◽  
Alexander J. Austerman ◽  
Robert Kluttz ◽  
Michael Roussel
Keyword(s):  
High Performance ◽  
Asphalt Pavement ◽  
Warm Mix Asphalt ◽  
Asphalt Binders ◽  
Reclaimed Asphalt Pavement ◽  
Moisture Susceptibility ◽  
Reclaimed Asphalt ◽  
Pavement Preservation ◽  
Asphalt Overlay ◽  
Structural Capacity

A high-performance thin asphalt overlay (HPThinOL) is specified as having a thickness of 1 in. or less and is used in applications requiring high levels of rutting and fatigue resistance. HPThinOLs are used as a pavement preservation strategy and are placed on pavements that have remaining structural capacity that is expected to outlive that strategy. Current specifications for HPThinOLs generally call for a polymer-modified asphalt (PMA). However, PMA binders are more expensive than unmodified asphalt binders. This expense, coupled with the higher binder content requirement generally associated with HPThinOL, could lead to an initial higher cost in relation to other pavement preservation strategies. Although the higher initial cost can be offset by incorporating high amounts of reclaimed asphalt pavement (RAP), the use of high amounts of RAP in PMA mixtures might adversely affect the mixture performance (stiffness, cracking, or workability). Warm-mix asphalt (WMA) technology may improve the workability of HPThinOL that incorporates high RAP content and PMA binders. This study evaluated the effect of PMA binders, high RAP content, and WMA technology on the stiffness, resistance to reflective cracking, moisture susceptibility, and workability of HPThinOL mixtures. PMA binders and high RAP content increased the stiffness of HPThinOL significantly; however, the use of WMA technology lowered mixture stiffness and improved workability. PMA may improve the cracking resistance, moisture susceptibility, and rutting resistance of high-RAP HPThinOL mixtures, depending on whether a WMA technology is used.

scholarly journals The Effect of Aging on the Cracking Resistance of Recycled Asphalt

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Mojtaba Mohammadafzali ◽  
Hesham Ali ◽  
James A. Musselman ◽  
Gregory A. Sholar ◽  
Aidin Massahi
Keyword(s):  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Fatigue Cracking ◽  
Asphalt Mixtures ◽  
Asphalt Binders ◽  
Reclaimed Asphalt Pavement ◽  
Cracking Resistance ◽  
Recycled Asphalt ◽  
Reclaimed Asphalt ◽  
Important Concern

Fatigue cracking is an important concern when a high percentage of Reclaimed Asphalt Pavement (RAP) is used in an asphalt mixture. The aging of the asphalt binder reduces its ductility and makes the pavement more susceptible to cracking. Rejuvenators are often added to high-RAP mixtures to enhance their performance. The aging of a rejuvenated binder is different from virgin asphalt. Therefore, the effect of aging on a recycled asphalt mixture can be different from its effect on a new one. This study evaluated the cracking resistance of 100% recycled asphalt binders and mixtures and investigated the effect of aging on this performance parameter. The cracking resistance of the binder samples was tested by a Bending Beam Rheometer. An accelerated pavement weathering system was used to age the asphalt mixtures and their cracking resistance was evaluated by the Texas Overlay Test. The results from binder and mixture tests mutually indicated that rejuvenated asphalt has a significantly better cracking resistance than virgin asphalt. Rejuvenated mixtures generally aged more rapidly, and the rate of aging was different for different rejuvenators.

scholarly journals SUGGESTING A SIMPLE DESIGN METHOD FOR COLD RECYCLED ASPHALT MIXES WITH ASPHALT EMULSION

2017 ◽  
Vol 23 (7) ◽  
pp. 966-976 ◽  
Author(s):  
Bahador BAZRAFSHAN MOGHADAM ◽  
Hamid FARHAD MOLLASHAHI
Keyword(s):  
Design Method ◽  
Mix Design ◽  
Asphalt Pavements ◽  
Asphalt Emulsion ◽  
Recycled Asphalt ◽  
Moisture Susceptibility ◽  
Asphalt Mixes ◽  
Reclaimed Asphalt ◽  
Significant Difference ◽  
Emulsified Asphalt

Although there are typical and well-known standard methods for designing hot mix asphalt in the world, there is no unique design method for cold recycled asphalt mixes. The current methods are mainly local or even dependent on technology owners due to the diversity of materials and qualitative control limitations. Currently, most of the design methods are based on 4 inch mold. The major problem of these methods is that in the mix design, the effect of aggre­gates larger than 25 mm is neglected, while this size of aggregates is used in the recycling projects. Therefore, there is a significant difference between in-situ and laboratory mix behaviors. So, 6-inch mold is used. In this study, a simple mix design has been obtained for reclaimed asphalt pavements (RAP) considering the different amount of emulsified asphalt, Portland cement, three gradations, moisture contents, temperatures, and curing times. For this reason, 315 samples were prepared. The results show that the mixes with aggregates larger than 25 mm have a significant difference with 25 mm and smaller aggregates sizes in terms of mechanical properties and moisture susceptibility. Therefore, 6-inch molds should be used for RAP materials that are larger than 25 mm in the mix design.

scholarly journals Moisture Susceptibility Evaluation of Asphalt Mixtures Containing Steel Slag Powder as Filler

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3211 ◽  
Author(s):  
Zhifeng Xiao ◽  
Meizhu Chen ◽  
Shaopeng Wu ◽  
Jun Xie ◽  
Dezhi Kong ◽  
...  
Keyword(s):  
Particle Size ◽  
Steel Slag ◽  
Asphalt Mixtures ◽  
Moisture Susceptibility ◽  
Freeze Thaw ◽  
Slag Powder ◽  
Steel Slag Powder ◽  
Split Test ◽  
Marshall Stability ◽  
Asphalt Mortar

The primary objective of this paper was to investigate the effect of replacing steel slag powder (SSP) with limestone filler (LF) with different contents as an inorganic anti-stripping agent on the moisture susceptibility of asphalt mixtures. Two traditional inorganic anti-stripping agents were selected for comparison, namely cement (CE) and slaked lime (SL). Apparent morphology, chemical compositions, and the particle size distribution of the four fillers were firstly studied. LF was replaced by SSP, CE, and SL with different contents, and then mixed with asphalt to prepare asphalt mortars. An 80 °C water immersion test was conducted to investigate the adhesion of asphalt mortar and aggregates, and an image analysis technique was utilized to evaluate the stripping of asphalt from the aggregates. A Marshall stability test and freeze-thaw split test were then conducted to analyze the effect of different fillers on the moisture susceptibility of asphalt mixtures. The results show that SSP contains a large amount of CaO, which indicates that SSP has a certain alkalinity. Compared with LF, SSP has a rougher surface texture and a finer particle size. Image analysis results show that the partially replacement of LF by SSP increases the asphalt coverage rate of aggregates, which means that SSP can improve the adhesion between asphalt mortar and aggregates. However, the excessive addition of SSP will result in a decrease in adhesion. The results of both the Marshall stability test and freeze-thaw split test demonstrate that CE, SL, and SSP can improve the moisture susceptibility of asphalt mixtures compared with the LF group, and that asphalt mixtures containing SSP have better moisture damage resistance than those with CE, but less such resistance than those with SL. With the increase of the amount of SSP replacing LF, the moisture susceptibility of the asphalt mixture decreases gradually. The optimum substitution amount of SSP was 25% of the total volume of fillers in this test.

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