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Sustainable Infrastructure Materials and Systems

A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Sustainable Engineering and Science".

Deadline for manuscript submissions: closed (31 July 2019) | Viewed by 64934

Special Issue Editors

Department of Civil and Environmental Engineering, University of Missouri, Columbia, MO, USA
Interests: smart pavement infrastructure; sustainable pavements; asphalt durability; pavement and civil infrastructure materials; tire rubber and waste plastic recycling
Professor and Director of UNH Center for Infrastructure Resilience to Climate, University of New Hampshire Durham, Department of Civil and Environmental Engineering, Durham, NH 03824, USA
Interests: characterization of asphalt concrete materials; pavement fatigue and fracture; recycled materials; aging of asphalt materials; impact of climate change and sea level rise on pavement structures and infrastructure systems; and adaptation alternatives for resilient infrastructure

Special Issue Information

Dear Colleagues,

There is an increasing societal demand and need for sustainable practices to be incorporated into our daily lives and surroundings. Built infrastructure is a large part of our society and a key to the prosperity of individuals and regions. There is a significant opportunity to incorporate sustainability into the planning, construction, and maintenance of built infrastructure. Surface transportation facilities, e.g., pavements, provide a substantial opportunity as they require a significant volume of material that must be quarried or recycled, processed, transported, and constructed. There have been considerable advances in technology related to the design and construction of pavements as well as the materials that are used. The incorporation of recycled materials—from recycled pavements and aggregates to construction and demolition waste, roofing shingles, rubber tires, plastics, and glass—has become increasingly common. In addition, technologies such as warm-mix asphalt (WMA) have been used to decrease emissions and energy requirements and/or to enhance construction quality under a range of conditions. Fracture-resistant concrete, built with coarse reclaimed asphalt pavement (RAP), has been used to create multi-layered, functionally graded pavement systems with enhanced sustainability. If designed and executed properly, these modern approaches to pavement materials and design provide economic, environmental, and, often, duty-cycle extension benefits.

Approaches to evaluate the impact of various pavement materials on the environment, e.g., life cycle assessment (LCA) methods and tools, have been developed and refined in recent years as well. The improved understanding of the contribution of pavement construction, maintenance, and operation to climate change has led to industry-wide changes in practices. Recent research has begun to explore the impact of climate change on pavement assets. Accordingly, approaches have been developed to assess vulnerabilities and to evaluate adaptation alternatives towards more resilient infrastructure in response to climate change.

The sustainability of pavements is clearly a hot topic of interest to researchers, practitioners, and agencies/owners of these assets. This Special Issue will include some of the exciting cutting-edge work that is being done by leading researchers around the world on sustainability issues related to pavement materials and technologies as well as on the assessment and evaluation of sustainability in regard to the impacts of pavements on and resulting from a changing climate.

Prof. William G. Buttlar
Prof. Jo E. Sias
Guest Editors

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • sustainable
  • pavement
  • life cycle assessment
  • LCA
  • recycling
  • RAP
  • RAS
  • WMA
  • asphalt
  • concrete
  • climate change
  • resilient
  • LCCA

Published Papers (13 papers)

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Research

36 pages, 4799 KiB  
Article
Life Cycle Assessment for Transportation Infrastructure Policy Evaluation and Procurement for State and Local Governments
by John T. Harvey, Ali A. Butt, Mark T. Lozano, Alissa Kendall, Arash Saboori, Jeremy D. Lea, Changmo Kim and Imad Basheer
Sustainability 2019, 11(22), 6377; https://doi.org/10.3390/su11226377 - 13 Nov 2019
Cited by 10 | Viewed by 3994
Abstract
Climate change is one of the defining challenges of our time, and achieving mitigation targets requires urgent action to identify and implement strategies for reducing greenhouse gas (GHG) emissions. However, identifying, quantifying, and then selecting among the many possible strategies to achieve GHG [...] Read more.
Climate change is one of the defining challenges of our time, and achieving mitigation targets requires urgent action to identify and implement strategies for reducing greenhouse gas (GHG) emissions. However, identifying, quantifying, and then selecting among the many possible strategies to achieve GHG reductions is difficult, especially without a standardized approach for comparison. Presenting alternatives in a mitigation supply curve is an approach that has been used previously to compare the costs and magnitude of mitigation potential for different strategies. Some of the critiques of this approach include the lack of a consequential perspective in determining mitigation and the lack of a life cycle perspective in quantifying mitigation and economic costs. This research uses the principles of consequential life cycle assessment and life cycle cost analysis to improve on the mitigation supply curve concept to support evaluation and procurement decisions for transportation infrastructure. Results from pilot studies for road infrastructure indicate that a consequential life cycle approach for mitigation supply curves is feasible and can support agency decision-making and communication regarding those decisions. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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21 pages, 3523 KiB  
Article
Cool Pavement Strategies for Urban Heat Island Mitigation in Suburban Phoenix, Arizona
by Sushobhan Sen, Jeffery Roesler, Benjamin Ruddell and Ariane Middel
Sustainability 2019, 11(16), 4452; https://doi.org/10.3390/su11164452 - 17 Aug 2019
Cited by 46 | Viewed by 6262
Abstract
Urban areas are characterized by a large proportion of artificial surfaces, such as concrete and asphalt, which absorb and store more heat than natural vegetation, leading to the Urban Heat Island (UHI) effect. Cool pavements, walls, and roofs have been suggested as a [...] Read more.
Urban areas are characterized by a large proportion of artificial surfaces, such as concrete and asphalt, which absorb and store more heat than natural vegetation, leading to the Urban Heat Island (UHI) effect. Cool pavements, walls, and roofs have been suggested as a solution to mitigate UHI, but their effectiveness depends on local land-use patterns and surrounding urban forms. Meteorological data was collected using a mobile platform in the Power Ranch community of Gilbert, Arizona in the Phoenix Metropolitan Area, a region that experiences harsh summer temperatures. The warmest hour recorded during data collection was 13 August 2015 at 5:00 p.m., with a far-field air temperature of about 42 C and a low wind speed of 0.45 m/s from East-Southeast (ESE). An uncoupled pavement-urban canyon Computational Fluid Dynamics (CFD) model was developed and validated to study the microclimate of the area. Five scenarios were studied to investigate the effects of different pavements on UHI, replacing all pavements with surfaces of progressively higher albedo: New asphalt concrete, typical concrete, reflective concrete, making only roofs and walls reflective, and finally replacing all artificial surfaces with a reflective coating. While new asphalt surfaces increased the surrounding 2 m air temperatures by up to 0.5 C, replacing aged asphalt with typical concrete with higher albedo did not significantly decrease it. Reflective concrete pavements decreased air temperature by 0.2–0.4 C and reflective roofs and walls by 0.4–0.7 C, while replacing all roofs, walls, and pavements with a reflective coating led to a more significant decrease, of up to 0.8–1.0 C. Residences downstream of major collector roads experienced a decreased air temperature at the higher end of these ranges. However, large areas of natural surfaces for this community had a significant effect on downstream air temperatures, which limits the UHI mitigation potential of these strategies. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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23 pages, 4881 KiB  
Article
A Framework for Introducing Climate-Change Adaptation in Pavement Management
by Jayne F. Knott, Jennifer M. Jacobs, Jo E. Sias, Paul Kirshen and Eshan V. Dave
Sustainability 2019, 11(16), 4382; https://doi.org/10.3390/su11164382 - 13 Aug 2019
Cited by 25 | Viewed by 4730
Abstract
Greenhouse gas emissions have caused global temperatures to rise since the mid-20th century accompanied by sea-level rise (SLR). Temperature increases and SLR-induced groundwater rise have been shown to cause premature pavement failure in many roadway structures. Hybrid bottom-up/top-down (hybrid) adaptation approaches have shown [...] Read more.
Greenhouse gas emissions have caused global temperatures to rise since the mid-20th century accompanied by sea-level rise (SLR). Temperature increases and SLR-induced groundwater rise have been shown to cause premature pavement failure in many roadway structures. Hybrid bottom-up/top-down (hybrid) adaptation approaches have shown promise by initially investigating an asset’s response to incremental environmental change and then identifying the timing of critical effects for budgetary planning. This improves practitioners’ understanding of the asset’s climate resiliency and informs adaptation-plan development to minimize both cost and risk. In this study, a hybrid approach to pavement adaptation with climate-change-induced temperature and groundwater rise is demonstrated at a case-study site in coastal New Hampshire. The hot-mix-asphalt (HMA) thickness that achieves a minimum of 85% reliability is calculated for 70 combinations of incremental temperature and groundwater rise. Increasing the base-layer thickness improves resiliency against rising temperatures, but rising groundwater diminishes this improvement demonstrating that both HMA and base-layer thickness increases are needed. Thirteen adaptation pathways are evaluated for pavement performance, life-cycle costs, and road-surface inundation over a 60-year pavement management period. A stepwise and flexible adaptation plan is developed that includes HMA overlays with prescribed thickness and application timing, base-layer rehabilitation options, and re-evaluation opportunities. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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14 pages, 2675 KiB  
Article
Binder and Mixture Fatigue Performance of Plant-Produced Road Surface Course Asphalt Mixtures with High Contents of Reclaimed Asphalt
by Ayad Subhy, Gustavo Menegusso Pires, Ana Jiménez del Barco Carrión, Davide Lo Presti and Gordon Airey
Sustainability 2019, 11(13), 3752; https://doi.org/10.3390/su11133752 - 09 Jul 2019
Cited by 8 | Viewed by 3410
Abstract
The aged properties of Reclaimed Asphalt (RA) binders are one of the main factors working against their utilisation in high-RA content (>30%) mixes for surface courses. Fatigue cracking is the main distress of surface courses that are manufactured with a high percentage of [...] Read more.
The aged properties of Reclaimed Asphalt (RA) binders are one of the main factors working against their utilisation in high-RA content (>30%) mixes for surface courses. Fatigue cracking is the main distress of surface courses that are manufactured with a high percentage of RA. This investigation presents results of the rheological and fatigue results of different asphalt mixtures and their recovered binders. The binders were recovered from asphalt mixtures that had been manufactured in asphalt plants using different amounts of RA with contents up to 60% with and without rejuvenators. Two different sources of RA were used, representing a moderately aged RA and an extremely aged RA. The Dynamic Shear Rheometer (DSR) was used to assess the fatigue-characteristics of the binders using time sweep tests while the fatigue characteristics of their mixtures were assessed using the Indirect Tensile Fatigue Test (ITFT). The fatigue data was analysed based on the cumulative dissipated energy approach in addition to traditional fatigue analysis. Results have shown that the ageing condition of RA significantly affects the fatigue properties of recovered binders. Binder and asphalt mixture fatigue results showed that RA contents up to 60% can produce comparable fatigue performance compared to lower percentages of RA in road surface course if the aged RA binder is sufficiently rejuvenated. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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39 pages, 19875 KiB  
Article
Realistic Traffic Condition Informed Life Cycle Assessment: Interstate 495 Maintenance and Rehabilitation Case Study
by Katie E. Haslett, Eshan V. Dave and Weiwei Mo
Sustainability 2019, 11(12), 3245; https://doi.org/10.3390/su11123245 - 12 Jun 2019
Cited by 9 | Viewed by 3653
Abstract
As construction costs continue to rise and adequate amounts of funding continues to be a challenge, the allocation of resources is of critical importance when it comes to the maintenance and rehabilitation (M&R) of highway infrastructure. A Life Cycle Assessment (LCA) methodology is [...] Read more.
As construction costs continue to rise and adequate amounts of funding continues to be a challenge, the allocation of resources is of critical importance when it comes to the maintenance and rehabilitation (M&R) of highway infrastructure. A Life Cycle Assessment (LCA) methodology is presented here that integrates realistic traffic conditions in the operational phase to compare M&R scenarios over the analysis period of a 26-km stretch of Interstate-495. Pavement International Roughness Index (IRI) were determined using American Association of State Highway and Transportation Officials (AASHTO) PavementME System. Meanwhile, vehicle fuel consumption and emission factors were calculated using a combination of Google Maps®, the United States Environmental Protection Agency (EPA) Motor Vehicle Emission Simulator, the second Strategic Highway Research Program (SHRP2) Naturalistic Driving Study, and MassDOT’s Transportation Data Management System. The evaluation of pavement performance with realistic traffic conditions, varying M&R strategies, and material characteristics was quantified in terms of Life Cycle Cost (LCC), Global Warming Potential (GWP), and Cumulative Energy Demand (CED) for both agencies and users. The inclusion of realistic traffic conditions into the use phase of the LCA resulted in a 6.4% increase in CED and GWP when compared to baseline conditions simulated for a week long operation duration. Results from this study show that optimization of M&R type, material selection, and timing may lead to a 2.72% decrease in operations cost and 47.6% decrease in construction and maintenance costs. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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15 pages, 7676 KiB  
Article
Mechanical and Microstructure Properties of Biochar-Based Mortar: An Internal Curing Agent for PCC
by Rayane Mrad and Ghassan Chehab
Sustainability 2019, 11(9), 2491; https://doi.org/10.3390/su11092491 - 28 Apr 2019
Cited by 46 | Viewed by 5204
Abstract
In pursuing sustainability targets, the construction industry has witnessed significant efforts exerted on exploring new alternatives for raw materials. Such initiatives aim to alleviate concerns of overexploitation of natural resources leading to their depletion. On a different note, the disposal of municipal solid [...] Read more.
In pursuing sustainability targets, the construction industry has witnessed significant efforts exerted on exploring new alternatives for raw materials. Such initiatives aim to alleviate concerns of overexploitation of natural resources leading to their depletion. On a different note, the disposal of municipal solid waste (MSW) has also become a major concern in some countries, such as the case of Lebanon, where illegal dumping continues to take its toll on the environment. Pyrolysis has been introduced as a biomass decomposition process of MSW and is considered an environmentally friendly process that can mitigate open dumping. However, pyrolysis produces significant amounts of biochar as a byproduct that in turn needs to be disposed of or treated. This research aims to investigate the viability of using biochar as a sustainable alternative material to sand in cementitious mortar composites. A thorough microscale physicochemical characterization of the biochar is conducted prior to its inclusion in mortar. Then, its incorporation as a partial replacement of sand in mortar is assessed at the mesoscale level, based on performance indices that included compressive strength and microstructure properties. Analysis of the experimental results are used to provide guidelines and recommendations as to the effective incorporation of biochar fraction in cementitious mortar. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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13 pages, 931 KiB  
Article
Carbon Footprint Estimation in Road Construction: La Abundancia–Florencia Case Study
by Marianela Espinoza, Noelia Campos, Rebekah Yang, Hasan Ozer, José P. Aguiar-Moya, Alejandra Baldi, Luis G. Loría-Salazar and Imad L. Al-Qadi
Sustainability 2019, 11(8), 2276; https://doi.org/10.3390/su11082276 - 16 Apr 2019
Cited by 22 | Viewed by 5641
Abstract
The environmental impact of road construction and rehabilitation can be associated with the increase of greenhouse gas (GHG) emissions, which are highly related to climate change. Consequently, departments of transportation have recently focused on the development and implementation of tools to evaluate the [...] Read more.
The environmental impact of road construction and rehabilitation can be associated with the increase of greenhouse gas (GHG) emissions, which are highly related to climate change. Consequently, departments of transportation have recently focused on the development and implementation of tools to evaluate the performance of projects and minimize GHG emissions. An example is the use of life cycle assessment (LCA) to analyze and quantify the environmental impact of a product, system, or process, from cradle to grave. In this regard, the present case study quantifies the carbon footprint associated with the construction of the La Abundancia–Florencia highway, located in the province of San Carlos in Costa Rica. The analysis is also intended to generate consciousness both in the public and private sectors on the environmental impacts of road construction. After an LCA study, it was determined that the construction of the hot mix asphalt (HMA) layer generates a carbon footprint of 65.8 kg of CO2e per km of road. In addition, it was evident that HMA production generates the greatest environmental impact, among all the considered LCA production and construction stages, with a GHG contribution of 38% to 39% from bitumen only. Consequently, special attention to HMA production is required in order to minimize GHG emissions. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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20 pages, 5427 KiB  
Article
Performance Analysis of Asphalt Mixtures Modified with Ground Tire Rubber Modifiers and Recycled Materials
by Punyaslok Rath, Joshua E. Love, William G. Buttlar and Henrique Reis
Sustainability 2019, 11(6), 1792; https://doi.org/10.3390/su11061792 - 25 Mar 2019
Cited by 32 | Viewed by 4303
Abstract
The usage of Ground Tire Rubber (GTR) in asphalt pavements has gained renewed interest due to its potential sustainability, economic, and performance benefits. This study focuses on asphalt mixtures designed with three different rubber modifier products including (1) a terminal-blend GTR, (2) a [...] Read more.
The usage of Ground Tire Rubber (GTR) in asphalt pavements has gained renewed interest due to its potential sustainability, economic, and performance benefits. This study focuses on asphalt mixtures designed with three different rubber modifier products including (1) a terminal-blend GTR, (2) a dry-process, chemically processed rubber product, and (3) a terminal-blend rubber-polymer hybrid product. The modifications were incorporated into Illinois Tollway’s approved Stone Matrix Asphalt (SMA) designs using (1) a base binder (PG 58-28), (2) a softer binder (PG 46-34), and (3) a softer binder with higher recycled content. Disk-shaped Compact Tension (DC(T)) test, Hamburg Wheel Tracking Test (HWTT) and Acoustic Emission (AE) tests were performed to characterize the mixtures. The fracture energy for most mixtures met the stringent criteria of 690 J/m2 and the rut depths measured were less than 6 mm at 20,000 wheel passes. A Hamburg-DC(T) plot suggests that higher amounts of RAP/RAS (RAP: Reclaimed Asphalt Pavement; RAS: Reusable Asphalt Shingles) can be successfully used if a suitably soft base binder is employed. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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13 pages, 2378 KiB  
Article
Characterization of Bitumen Modified with Pyrolytic Carbon Black from Scrap Tires
by Haopeng Wang, Guoyang Lu, Shuyin Feng, Xiaobo Wen and Jun Yang
Sustainability 2019, 11(6), 1631; https://doi.org/10.3390/su11061631 - 18 Mar 2019
Cited by 31 | Viewed by 4517
Abstract
Pyrolytic carbon black (CBp) from scrap tire pyrolysis is a potential modifier for the bitumen industry. Binders containing different contents of CBp were prepared and experimentally investigated to examine the effects of CBp on the electrical and thermal conductivity, [...] Read more.
Pyrolytic carbon black (CBp) from scrap tire pyrolysis is a potential modifier for the bitumen industry. Binders containing different contents of CBp were prepared and experimentally investigated to examine the effects of CBp on the electrical and thermal conductivity, conventional physical properties, rheological properties, high-temperature antirutting performance, aging resistance, and storage stability. Laboratory test results indicated that the incorporation of CBp effectively improves the electrothermal properties, rheological properties, high-temperature rutting resistance, and aging resistance. It also increases the viscosity and decreases the storage stability of bitumen. The study confirms that CBp-modified bitumen with proper selection of content can be a multifunctional paving material. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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14 pages, 3853 KiB  
Article
Evaluation of the Improvement Effect of Limestone Powder Waste in the Stabilization of Swelling Clayey Soil
by José Luis Pastor, Roberto Tomás, Miguel Cano, Adrián Riquelme and Erick Gutiérrez
Sustainability 2019, 11(3), 679; https://doi.org/10.3390/su11030679 - 28 Jan 2019
Cited by 44 | Viewed by 5489
Abstract
The natural stone industry generates large amounts of industrial waste every year. Limestone powder produced by the activity of this industry is dumped into landfills, generating an environmental impact that could be reduced by using this waste as a binder in building materials. [...] Read more.
The natural stone industry generates large amounts of industrial waste every year. Limestone powder produced by the activity of this industry is dumped into landfills, generating an environmental impact that could be reduced by using this waste as a binder in building materials. In the present work, the use of this by-product as an addition for soil improvement of clayey soils has been studied. The tested natural soil is a soft clay from southeastern Spain, which has been mixed by adding 5, 10, 15, 20, and 25% of dry limestone dust by total dry weight of the soil. The natural soil and the additive have been characterized, in addition to the common geotechnical tests, by means of X-Ray diffraction and X-Ray Fluorescence. The improvement of the geotechnical properties of the mixed soil has been evaluated by means of the change in the Atterberg limits, free swell index, unconfined compressive strength, and one-dimensional consolidation test. The change in the microstructure of the mixed soil has been studied by scanning electron microscopy. In general, the results obtained show an increase in the strength of the soil and a reduction of its deformability when limestone powder is added. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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20 pages, 1663 KiB  
Article
Reclaimed Polymers as Asphalt Binder Modifiers for More Sustainable Roads: A Review
by Luzana Brasileiro, Fernando Moreno-Navarro, Raúl Tauste-Martínez, Jose Matos and Maria del Carmen Rubio-Gámez
Sustainability 2019, 11(3), 646; https://doi.org/10.3390/su11030646 - 26 Jan 2019
Cited by 141 | Viewed by 8379
Abstract
The use of polymer-modified binders in asphalt mixtures has become more widespread due to their reduced thermal susceptibility and improved rutting and fatigue resistance. Nevertheless, their high cost limits their application, thus making the use of reclaimed polymers (RP) an interesting alternative for [...] Read more.
The use of polymer-modified binders in asphalt mixtures has become more widespread due to their reduced thermal susceptibility and improved rutting and fatigue resistance. Nevertheless, their high cost limits their application, thus making the use of reclaimed polymers (RP) an interesting alternative for both reducing price and extending the service life of pavements. This paper; therefore, presents a comparative review of the recycled polymers most commonly studied as bitumen modifiers: polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), ethyl vinyl acetate (EVA), and ground tire rubber (GTR), in order to facilitate their selection and extend the use of the bitumen. The differences in terms of melting point, mixing conditions, and maximum quantity of added polymer are analyzed. Moreover, their effect on the mechanical behavior of the asphalt binders and their stability with and without the use of additives is presented. According to the literature revision, the performance of the new binder is more influenced by the kind of polymer that was incorporated and the mixing conditions than by the base bitumen that was chosen, although rheological evaluation is needed to fully understand the modification mechanisms of the modified binder. In general terms, plastomers have a stronger effect in terms of increasing the stiffness of the bitumen in comparison with crumb rubber (elastomers), thus providing an improved rutting resistance. The joint use of polyethylene (plastomer) and crumb rubber (elastomer) can be an interesting option for its recycling potential and mechanical performance, although further study is needed to achieve stable bitumen across the entire range of temperatures; additives, such as maleic anhydride (MA), are commonly employed to improve the stability of the binder and enhance its characteristics, but their use could limit the economic benefits of using recycled materials. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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17 pages, 3076 KiB  
Article
A Sustainability Perspective for Unbound Reclaimed Asphalt Pavement (RAP) as a Pavement Base Material
by Christina Plati and Brad Cliatt
Sustainability 2019, 11(1), 78; https://doi.org/10.3390/su11010078 - 24 Dec 2018
Cited by 32 | Viewed by 5454
Abstract
The present study aims to investigate reclaimed asphalt pavement (RAP) materials for utilization for a pavement base layer material with the goal towards increasing the reutilization of materials and the movement towards increased pavement sustainability. Reduced cost for materials and transportation of materials, [...] Read more.
The present study aims to investigate reclaimed asphalt pavement (RAP) materials for utilization for a pavement base layer material with the goal towards increasing the reutilization of materials and the movement towards increased pavement sustainability. Reduced cost for materials and transportation of materials, overall environmental benefits and many other advantages have led to increased interests in utilizing RAP in pavements including as base materials for highway/roadway construction projects. The potential advantages of utilizing RAP as an unbound base material are known; however, its overall application is still limited partially due to the lack of systematic evaluation studies for the parameterization of RAPs mechanical behavior in pavement design. With this in mind, the current investigation focuses on the resilient modulus (Mr) properties of RAP aggregates in terms of a material’s elastic response. Experimental data from tri-axial stress tests on specimens consisting of RAP, aggregates and a mixture of both materials are investigated. A number of constitutive models for the description of mechanical behavior of RAP materials are investigated. The required procedures for determining the constitutive constants of the constitutive models is outlined for the aforementioned materials. A comparative analysis is applied, and the related results are evaluated. The main conclusion is that RAP materials can be utilized as a base material in the framework of pavement sustainability, as its behavior under loading conditions are similar to virgin aggregate (VA) materials and can be simulated by using appropriate constitutive models for pavement design processes. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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17 pages, 5274 KiB  
Article
Influences of Clay Brick Particles on the Performance of Cement Stabilized Recycled Aggregate as Pavement Base
by Yinghao Miao, Weixiao Yu, Yue Hou, Cong Liu and Linbing Wang
Sustainability 2018, 10(10), 3505; https://doi.org/10.3390/su10103505 - 30 Sep 2018
Cited by 11 | Viewed by 2819
Abstract
This paper presents an investigation on the influences of clay brick particles on the performance of cement stabilized recycled aggregate as pavement base. The comparative tests of unconfined compressive strength, compressive modulus of resilience, frost resistance, scouring resistance, drying shrinkage and temperature shrinkage [...] Read more.
This paper presents an investigation on the influences of clay brick particles on the performance of cement stabilized recycled aggregate as pavement base. The comparative tests of unconfined compressive strength, compressive modulus of resilience, frost resistance, scouring resistance, drying shrinkage and temperature shrinkage of 6 kinds of mixtures with different coarse and fine clay brick particle contents were carried out. Test results showed that the unconfined compressive strength of cement stabilized recycled aggregate was compromised by the clay brick particles, especially the lateral strength. The coarse clay brick particles had little influence on the compressive resilience modulus of the mixture, while the fine clay brick particles could significantly increase it. The frost resistance of the mixture increased first and then slightly decreased with the increase of the content of coarse clay brick particle, while it increased with the increase of fine particle content. The scoured mass loss increased with the increase of coarse clay brick particle content. However, it is discovered that the fine clay brick particles had almost no influences on the scoured mass loss. The addition of both coarse and fine clay brick particles could decrease the drying shrinkage of the mixture at early construction stage. The temperature shrinkage performance of the mixture was not so sensitive to the addition of clay brick particles. Generally, the cement stabilized recycled aggregate with clay brick particles could meet the requirements of the pavement base in many cases but it needs to be optimized in application with consideration of the load and climate conditions. Full article
(This article belongs to the Special Issue Sustainable Infrastructure Materials and Systems)
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