Effect of Recycled Asphalt Pavement on Mechanistic Performance of Hot Mix Asphalt PDF Download
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Author: Adjamoussi David Adje
Publisher:
ISBN:
Category : Pavements, Asphalt
Languages : en
Pages : 226
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Author: Adjamoussi David Adje
Publisher:
ISBN:
Category : Pavements, Asphalt
Languages : en
Pages : 226
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 192
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Author: Amy Epps Martin
Publisher:
ISBN: 9780309481045
Category : Asphalt
Languages : en
Pages : 284
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"More than 90 percent of highways and roads in the United States are built using hot-mix asphalt (HMA) or warm-mix asphalt (WMA) mixtures, and these mixtures now recycle more than 99 percent of some 76.2 million tons of reclaimed asphalt pavement (RAP) and about 1 million tons of recycled asphalt shingles (RAS) each year. Cost savings in 2017 totaled approximately $2.2 billion with these recycled materials replacing virgin materials. The TRB National Cooperative Highway Research Program's NCHRP Research Report 927: Evaluating the Effects of Recycling Agents on Asphalt Mixtures with High RAS and RAP Binder Ratios presents an evaluation of how commercially available recycling agents affect the performance of asphalt mixtures incorporating RAP and RAS at high recycled binder ratios."--
Author: Xiomara A. Sanchez-Castillo
Publisher:
ISBN:
Category :
Languages : en
Pages : 190
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Book Description
The use of Reclaimed Asphalt Pavement (RAP), sometimes called Recycled Asphalt Pavement, in Hot Mix Asphalt (HMA) provides many benefits and has been successfully used in Ontario for several years. The production and usage of this material results in numerous environmental and economic advantages. Using RAP in HMA has various proven benefits including: reuse of high quality materials, saves on dwindling non-renewable aggregate resources, diverts large volumes of materials from overloaded landfills, reduces road building costs and contributes significantly to provincial and municipal recycling obligations. However, the usage of this material is still very conservative. Several challenges can be faced when introducing RAP in HMA, particularly in higher amounts. The characteristics of the RAP, particularly the aged (stiffer) asphalt cement (AC) in the recycled material, can affect the performance of the mix. The primary concern with increasing RAP percentages in HMA mixes are its effects on endurance against fatigue and thermal cracking. The common question in many agencies within the pavement industry is whether RAP acts as a “black rock” or the aged AC in RAP blends with the new AC in the mix. Accordingly, this research evaluated the impact that RAP in varying percentages has on a conventional Ontario mix, Superpave (SP) 12.5mm, and provided some new guidelines on the usage of RAP. Using virgin aggregates and RAP collected from a local contractor, twelve mixtures were modelled in the laboratory, with 0%, 20%, and 40% RAP contents and AC with different Performance Grade (PG). The research also examined how the addition of RAP to HMA alters the performance of the mix, and how HMA can be tested to determine the RAP content. This research intended to answer the following questions: First, can the RAP percentage be determined from the recycled hot mix asphalt characteristics or performance? And second, can the blended binder PG be deduced from performance testing of recycled hot mix? This research demonstrated that is possible to design Superpave mixes incorporating 20% RAP and 40% RAP without compromising the specified consensus properties and volumetric characteristics. Based on the results, it was determined that the performance of the recycled hot mixes regarding low temperature cracking, rutting and stiffness, which is related to the fatigue susceptibility of the mix, was simultaneously influenced by the RAP content and the virgin asphalt PG. The effect of the RAP addition was more dramatic for the mixes with virgin binder PG 52-xx than for the mixes with PG 58-xx. A method to determine the presence and quantity of RAP was formulated, and also an estimation of the performance grade of the resulting blended binder without extraction and recovery of the asphalt was possible.
Author: Asphalt Institute
Publisher:
ISBN: 9781934154175
Category : Asphalt
Languages : en
Pages : 102
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Author: Hawraa Kadhim
Publisher:
ISBN:
Category : Asphalt pavements
Languages : en
Pages : 17
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Book Description
The use of reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) has been increasing in the last few decades because of its cost benefits and because of a compelling need to preserve the environment and natural resources. It is commonly assumed that HMA containing RAP (HMA-RAP) has an improved resistance to permanent deformation (rutting) and decreased resistance to the fatigue cracking. This is due to the fact that asphalt binder contained in the RAP has been oxidized over the years and is typically stiffer than virgin asphalt binder. However, during the production stage of the HMA-RAP, the blending between aged and virgin asphalt binders would be incomplete or partial, which would lead to heterogeneous distribution of the aged and virgin asphalt binders within the asphalt mix with RAP. Therefore, the purpose of this article is to evaluate the effect of silo storage on the blending mechanism between virgin and RAP asphalt binders and the impact that this would have on performance of the mix. Two plant-produced asphalt mixes (HL-3 and HL-8), typically used in the province of Ontario for surface and base courses in flexible pavements, were considered in this study. The mixes were designed with 15 and 30 % RAP, respectively, and the samples were collected immediately after the production (0 h) or at different silo storage times (1, 4, 8, and 12 h). The temperatures of the collected materials were closely monitored and recorded. The findings of this research indicated that silo-stored samples exhibited some improvement in their rutting and fatigue resistance. The examination of the dynamic modulus master curves indicated that the rheology of the mixes evolved with silo storage and that blending between the aged and the virgin binders has been improved.
Author: Hawraa Kadhim
Publisher:
ISBN:
Category : Asphalt concrete
Languages : en
Pages : 158
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Book Description
Reclaimed Asphalt Pavement (RAP) has been favoured over virgin materials in the light of the unstable cost of virgin asphalt binders, shortage of quality aggregates, and compelling need to preserve the environment and natural resources. Mixes containing up to 20% RAP are commonly considered to have similar behaviour to virgin mixes. However, during the production process of HMA with RAP, the blending between aged and virgin binders would be partial, which would create heterogeneity in distribution of the aged recycled binder and the soft virgin binder in the HMA-RAP mixes. Hence, it is important to control the blending process between old and new binders to obtain more homogenous mix. Therefore, the main objectives of this research are to examine the kinematics of blending of aged and virgin binders by considering the time-temperature effect during mixing and silo-storage, and assess the thermo-mechanical behaviour of Hot Mix Asphalt (HMA) containing RAP at different blending states. The asphalt mixes used in this research were produced and collected at two plants (Plant 1) and (Plant 2) located in Ontario, Canada. Two Marshall mixes were produced and collected from Plant 1 including a surface course HL-3 containing 15 percent RAP and a base course HL-8 containing 30 percent RAP. These mixes were labelled as 1HL-3 and 1HL-8 respectively. In addition, two Marshall mixes were produced and collected from Plant 2 including a surface course HL-3 containing 20 percent RAP and a base course HL-8 containing 40 percent RAP. These mixes were labelled as 2HL-3 and 2HL-8 respectively. To investigate the impact of storage time on the blending progress and achieving a cohesive final binder, the mix samples were collected as a function of storage time in the silo. The first sampling was done immediately after production (t = 0-hour), and then at several time intervals of silo-storage; i.e., at 1, 4, 8, and 12 hours. In case of Plant 2, the samples were additionally collected after 24-hour of storage time. All samples were then kept in a storage room at 7ʻC until the day of compaction to minimize any further blending between aged and virgin binder. To understand the blending phenomena and its effect on the performance of the pavement, a multi-scale investigation is carried out. The blending was examined in terms of micro-mechanical and rheological properties. The microstructure of the blending zones were examined under The Environmental Scanning Electron Microscope (ESEM). In addition the effect of the silo-storage time on the rheology of the binders was investigated. The results indicate that increasing the interaction time and temperature between the aged and virgin binder significantly results in a better blending. The performance of RAP-HMA with respect to the silo-storage time was examined using Dynamic Modules Test, Thermal Stress Restrained Specimen Test (TSRST), Rutting Test, and Flexural Beam Fatigue Test. The experimental data indicates that samples collected after 12-hour of silo storage exhibited a reduction in the stiffness due to better blending of aged and virgin binder. In addition, the 12-hour samples showed enhancement in their fracture temperature, rutting depth, and fatigue life, accompanied with a better blending between their aged and virgin binder. On the other hand, the samples that collected after 24-hour silo-storage had a higher stiffness in comparison with the 8 and 12-hour samples. Moreover, the AASHTOWare Pavement Mechanistic-Empirical Design was utilized to examine the effect of the 12-hour silo-storage time on the long term performance of the pavements. Four pavement structures have been designed for this purpose. These pavements have the same structure of their granular A, granular B, and the subgrade. Yet, the first layer (surface course and base course) is a silo-storage time-dependent. The long-term field performance prediction indicates a slight improvement with the 12-hour pavements (Plant1 12hrs and Plant2 12hrs). However, it should be noted that AASHTOWare Pavement Mechanistic-Empirical Design does not appear to properly capture the effect of blending in the pavement performance. The collected experimental evidences unveils correlations between time-temperature effects and mixture performance. Based on these findings, the research provides practical recommendations to the professionals of the Canadian asphalt industry for a better use of RAP. Ultimately, this research recommends a 12-hour silo-storage time for the RAP-HMA for better performance and durability of the mixes.
Author: Randy Clark West
Publisher: Transportation Research Board
ISBN: 0309259134
Category : Pavements, Asphalt
Languages : en
Pages : 162
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Book Description
TRB's National Cooperative Highway Research Program (NCHRP) Report 752: Improved Mix Design, Evaluation, and Materials Management Practices for Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content describes proposed revisions to the American Association of State Highway and Transportation Officials (AASHTO) R 35, Superpave Volumetric Design for Hot Mix Asphalt, and AASHTO M 323, Superpave Volumetric Mix Design, to accommodate the design of asphalt mixtures with high reclaimed asphalt pavement contents.
Author: Thomas Bennert
Publisher:
ISBN:
Category : Asphalt emulsion mixtures
Languages : en
Pages : 158
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Author:
Publisher: Transportation Research Board
ISBN: 0309155649
Category : Asphalt concrete
Languages : en
Pages : 285
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