Research

Chemistry of RCA Leachate in Base Course Applications

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Uncertainty regarding the high pH, high alkalinity leachate from recycled concrete aggregate (RCA) leachate limits the use of RCA as a substitute for virgin aggregate in pavement base course. The purpose of this work is to understand the time-dependent behavior of leachate chemistry from RCA in pavement base course applications and the persistence of high pH leachate in the environment. A state-of-the-art review of the existing laboratory and field investigations of RCA leachate chemistry identifies discrepancies in field and laboratory measurements of RCA leachate pH. Critical evaluation of the existing investigations indicates that conventional laboratory methodology, which employs abrasive, closed system batch reactors, is not representative of field conditions. In order to understand the physicochemical factors that control RCA leachate pH and alkalinity the physical properties, solid phase chemistry, and time-dependent leachate chemistry were integrated into a geochemical model. The model illustrates that RCA leachate chemistry can be described by two parameters: portlandite content of RCA available for dissolution, and the availability of carbon dioxide. The fundamental understanding of time-dependent behavior of RCA leachate chemistry was extended to applications in pavement base course using RCA-leachate contact times according to AASHTO base course drainage quality standards. Contact time experiments indicate that longer contact times do not increase peak pH associated with RCA leachate pH, such that using RCA in base course applications poses no additional concern regarding drainage quality, and that RCA leachate pH will equilibrate to a near-neutral value, pH 7.7 and pH 8.5 given sufficient exposure to atmospheric carbon dioxide or soil acidity.  The findings of this study can be used to provide guidelines for practice to ensure safe and wise use of RCA base course.

 

The full thesis may be found in the following file:

Sanger_M.S. Thesis

Recycled Materials Web Map

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Recycled Materials Web Map

The Recycled Materials Web Map (RMWM) is an on-line Geographic Information System (GIS) web application that connects producers and consumers of recyclable material was developed to assist engineers and contractors in the beneficial reuse of nonhazardous recycled materials in transportation projects. The RMWM is comprised of four core layers: providers, stockpiles, specifications, and case studies. Providers of recycled material can locate their facility and enter contact information. The stockpile layer, connected to the provider layer, allows facility managers to add or update information about their recycled material stockpiles including material type(s), application(s), availability, and cost information. Multiple stockpiles can be associated with each provider. The specification layer includes both Department of Transportation (DOT) specifications and environmental regulations pertaining to the beneficial reuse of recycled material based on specific location, material type, and application. The case study layer locates projects that successfully utilized recycled materials and includes information regarding the material type, application, volume data, and any additional documentation. The web map utilizes search capabilities to locate nearby stockpiles to minimize transportation costs that typically dictate the use of large volumes of materials. The RMWM provides key information which engineers and contractors need to successfully utilize recycled materials, thereby preserving limited natural resources and benefiting the project and society as a whole.

The RMWM is hosted at the Center for Advanced Public Safety (CAPS) at The University of Alabama and was funded through a pooled fund supporting the Recycled Materials Resource Center (RMRC) at the University of Wisconsin-Madison. During the first phase of this work, the RMWM was designed, developed, and tested with preliminary data. A beta version of the web application has been demonstrated to be a useful tool, but there are several areas of the application that need to be addressed for widespread use of this web tool. To address these areas, The University of Alabama has been contracted for a second phase of the project which will wrap up in 2019.

 

RWM

System Wide Life Cycle Benefits of Fly Ash

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The use of recycled materials in highway construction has the potential to achieve significant benefits affecting the triple-bottom line (environment, prosperity, society). Such benefits include reducing the need for mining virgin materials and transportation (in-situ applications), reducing environmental impacts of processing and transportation, and reducing life cycle costs. Although state departments of transportation (DOTs) have been in the forefront of introducing recycled materials, they have not been able to clearly convey the benefits in a quantitative and transparent manner using easily understood metrics. The main reason for this is the difficulty in tracking the quantities of recycled materials used in state DOT projects. To better define the benefits of using recycled materials, the RMRC undertook a project with two objectives. The first objective was to develop a means of tracking and reporting quantities used in state DOT projects annually. The second objective is to provide a tool to quantitatively analyze and report the environmental and life cycle assessment of using recycled materials in highway construction. A suitable method was recommended after studying how RMRC member states currently track their recycled materials quantities. Subsequently, an LCA analysis of three environmental parameters, energy use, water consumption and CO2 emissions, showed significant environmental benefits when states used recycled industrial byproducts such as fly ash.

2015 World of Fly Ash Conference

Assessing the Life Cycle Benefits of Recycled Material in Road Construction

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Life cycle assessments of recycled material use in roadways are currently not well understood or well documented. The Recycled Materials Resource Center’s (RMRC) research is aimed at quantitatively determining the environmental and economic benefits of using recycled material in road construction. Two case studies were performed to analyze the impacts of incorporating recycled material in the reconstruction of two major roadways using life cycle assessment (LCA) and life cycle cost analysis (LCCA) tools. Results from both roads show that the use of recycled materials reduces energy and water consumption, greenhouse gas emissions, and cost. Because typical roadway construction projects do not separately track the extensive use of recycled materials, the RMRC was unable to utilize the LCA and LCCA technology in the first roadway’s analysis without making significant assumptions for the inputs. To clarify and verify some of these assumptions, the second roadway project was undertaken. This second case study is being studied to determine a better methodology for data collection with fewer assumptions, in addition to assessing the benefits of recycled material use. The methodology for data collection and analysis developed through the second project can be used to conduct LCAs and LCCA for future highway construction projects with greater confidence.

Geo-Chicago 2016 

 

Recycled Materials Network: Connecting Producers to Consumers Website

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Over half a billion tons of recyclable material such as foundry sand, coal combustion products and construction and demolition debris, are produced each year in the United States. Many of these materials have beneficial use in transportation construction projects. Unfortunately, the widespread use of these materials is hindered by a lack of information; either an understanding of the beneficial use of the recycled material or simply finding an adequate source of the recycled material.

Providing potential consumers of recycled materials an on-line location-based information Network that includes recycled material sources, past projects that used recycled material, and regulations pertaining to the use of recycled material in construction projects is needed. Information about recycled material including: type(s) of material, availability, producer throughput, cost, and material characteristics should be included in the site. In addition to the map of recycled material sources, two additional map layers: case studies and regulations, need to be available on the site. The case study layer will focus on past projects that employed recycled material in the design and construction. The regulations layer will display state regulations pertaining to the beneficial use of recycled material. By providing locations and quantities of available recycled materials, examples of past case studies, and regulations governing recycled material, a single Recycled Materials Network to promote the use of recycled material will be created.

To access the Network, please visit:

http://rmwm.caps.ua.edu/     RMRC-SOW-Web-Map-to-Link-Materials

I-94 Recycled Materials Case Study

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The Recycled Materials Resource Center (RMRC) analyzed the environmental benefits of incorporating recycled material in the reconstruction of Interstate 94 (I-94) in Kenosha County, WI, using BE2ST-in-Highways. BE2ST-in-Highways integrates various supporting databases and uses life cycle assessment (LCA) and life cycle cost analysis (LCCA) techniques to evaluate the overall impact of highway construction projects. An alternative construction project that contains recycled materials is typically analyzed in comparison to a reference project that contains virgin materials. With the goal of quantitatively determining the environmental benefits of using recycled materials, the RMRC targeted a one-mile stretch of the Kenosha County portion of the I-94 North-South Freeway Project because it incorporates recycled materials in its reconstruction. Recycled materials used in the project include fly ash, bottom ash, foundry sand, recycled concrete aggregate (RCA), and recycled asphalt pavement (RAP). Preliminary results of the BE2ST-in-Highways analysis of the I-94 mainline reconstruction show that the use of recycled materials reduces the environmental impact of the highway construction in all criteria over its lifetime.

For more information:

US Hwy 12/18/151 at Verona Road-Beltline: Recycled Materials Case Study

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The eastbound Beltline Highway (US 12/18) from Whitney Way to Seminole Highway, a 1.5 mile stretch, is undergoing a reconstruction and expansion three lanes from fall 2014 to spring 2016. The RMRC research team proposes to use this project to better determine a methodology for gathering the data needed for the inputs of the life cycle assessment (LCA) and life cycle cost analysis (LCCA) tool, PaLATE, as well as assess the benefits of using recycled materials in the project. The project will be used in preparation for more analyses of member-state roads. Examples of user inputs include material volumes, road dimensions, equipment used, etc. During past research, the research team has been unable to utilize LCA and LCCA technology without making significant assumptions for the inputs. The Beltline project offers an opportunity to develop a method for data collection that could eliminate assumptions from the analyses.

For more information:

Use of Recycled Materials Behind MSE Walls

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To ensure long-term integrity of MSE walls, reinforced backfills consisting predominantly of coarse-grained materials have been recommended and used. This limitation on material type can significantly increase the cost of construction on some projects because of the cost of transporting select material to the construction site when local select fill is not available. At the same time, industrial operations and construction activities create coarse-grained materials that must be disposed. Again, producers of such materials must pay transportation costs, as well as disposal fees, to discard these materials. One solution is to recycle these materials and use them as alternative reinforced backfill.

Throughout the U.S., substantial amounts of recycled asphalt pavement (RAP) and recycled concrete aggregate (RCA) are being produced through reconstruction activities as well as granular industrial byproducts such as foundry sand/slag, bottom ash, and iron/steel slag. If these materials were used as reinforced backfill for MSE walls, transportation and disposal costs for these materials could be greatly reduced, translating into significant savings for state departments of transportation. Furthermore, such activities would promote sustainable construction, preserve natural resources, and reduce carbon footprint and landfill disposal in highway construction. There are reports of the use of these materials as reinforced backfill as well as research on their properties relevant to reinforced backfill requirements. Further focused research of recycled materials needs to be done to determine if their use as MSE wall reinforced backfill is considered suitable for a more sustainable and potentially economical design and develop design and construction recommendations.

The full report can be found:

MSE Wall Final Report

Summary

Incorporating a Fly Ash Stabilized Layer Into Pavement Design

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Pavements were designed and constructed at two sites in southern Wisconsin employing a layer stabilized in situ with fly ash.  One pavement is for a residential subdivision.  The other is a test section located in a secondary highway that was recently reconstructed.  A control test section employing a conventional cut-and-fill approach was also constructed in the secondary highway.  Fly ash was used to increase the strength and stiffness of the fine-grained subgrade at both sites, which was soft prior to stabilization.  Pavements at both sites were designed using the 1993 AASHTO method for flexible pavements so that their structural number would be equivalent to that of the conventional pavement originally called for in the design. Measurements of California bearing ratio (CBR) and resilient modulus (Mr) were used with the correlation charts for granular subbase materials in the AASHTO manual to define layer coefficients for the stabilized layers.  Tests were also conducted on specimens collected during construction to verify that the in situ mixture had similar properties as anticipated during design.  The pavement at one of the sites is being monitored seasonally using a falling weight deflectometer and pavement distress surveys.  The monitoring program has indicated that the pavements constructed with fly ash stabilized layers provide comparable stiffness to the conventional pavements employing a cut-and-fill approach.  No signs of distress have been observed in the pavements constructed with a stabilized layer.

More information can be found in the following file:

Bin-Shafique Report

Summary

Fly Ash Stabilization Of Gravel Roads

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Investigation into a field site where cementitious fly ashes (Class C and off-specification) were used to stabilize road-surface gravel (RSG) to form a base during construction of a flexible pavement in Chisago County, MN.  The project involved conversion of a gravel road to a paved road.  It consisted of mixing fly ash (10% by dry weight) and water into the gravel surface to a depth of 254 mm and compacting the mixture to form a firm base, and placement of an HMA surface.  California bearing ratio (CBR), resilient modulus (Mr), and unconfined compression (qu) tests were conducted on a composite sample of the RSG alone and the fly-ash stabilized RSG (S-RSG) samples prepared in the field and laboratory to evaluate how addition of fly ash improved the strength and stiffness.  In situ testing was also conducted on the subgrade and S-RSG with a soil stiffness gauge (SSG), dynamic cone penetrometer (DCP), and falling weight deflectometer (FWD). A pan lysimeter was installed beneath the roadway to monitor the quantity of water percolating from the pavement and the concentration of trace elements in the leachate.  Column leach tests were conducted in the laboratory for comparison.

More information can be found in the following file:

CR53 Final Report     CR53_Appendix   Summary

Recycled Unbound Materials

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The objective of this project was to characterize the properties of crushed recycled concrete (RCA) and asphalt pavement (RAP) as unbound base without being stabilized, to assess how RCA and RAP behave in the field and to determine how pavements can be designed using RCA and RAP. Issues to be considered include variability in material properties, purity of material, climatic effects, how to identify and control material quality, and leaching characteristics.  This project included laboratory specimen and large-scale model tests and evaluation of field data from MnROAD test sections constructed using recycled materials.  To identify the characteristics of RAP and RCA typically available in different parts of the country, samples were obtained from eight states: California, Colorado,Michigan, Minnesota, New Jersey, Ohio, Texas, and Wisconsin covering a geographically diverse area.  A conventional base course was used as a control material. The extensive investigation undertaken on RCA and RAP indicate that these materials are generally suitable for unbound base course applications and they show equal or superior performance characteristics compared to natural aggregates in terms of stiffness, freeze-thaw and wet-dry durability, and toughness.  Their typical compositional and mechanical properties and their variability are defined in this study providing a basis for design considerations.  Their relative differences from natural aggregate such as temperature sensitivity, plastic deformations, and water absorption and retention characteristics are also well established.

More information can be found in the following file:

Recycled Unbound Materials MnDOT Report

Summary

Cost Effective Means of Managing Poor Condition Pavements

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Tight budgets and dwindling state and federal revenue hinder efforts of transportation agencies to resurrect pavements in poor condition. As a “stop-gap” measure, some agencies simply allow roads to deteriorate to gravel. However, this approach can be costly over the long-term and often results in dissatisfied users. This research project identifies construction treatments and/or materials that can be used to extend the service life of pavements in poor condition. These treatments are intended to be economical and practical “stop-gap” measures until permanent and affordable solutions are available.  They are not an “alternative” to reconstruction.

More information can be found in the following file:

CFIRE Final Report

 

Engineering Criteria for Shredded Waste Tires

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Waste tires are essentially a solid waste and recycling of tires will likely need an analysis and exemption from the Wisconsin Department of Natural Resources. An analysis is needed to support the department’s ultimate decision. Furthermore, the information generated through waster characterization testing should be of use in evaluating disposal and recycling proposals of abandoned tire piles.

More information can be found in the following file:

Edil Bosscher Final

 

Summary

Environmental Suitability Of Scrap Tires

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Since rain water will percolate through earth structures constructed with shredded tires, concern exists regarding the potential for leaching of organic and inorganic constituents.  Tires contain numerous ingredients such as carbon black,vulcanizing agents, metallic reinforcements, antioxidants, pigments, accelerators and may also contain petroleum residues obtained through use. Thus, leaching studies have focused on both organic and inorganic compounds.

More information can be found in the following file:

Tire Leaching Report

Groundwater Impacts from Coal Combustion Products

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his report describes a computer application that was developed to assess impacts to groundwater caused by leaching of trace elements from CCPs used in highway construction.  Laboratory and field experiments conducted to verify the application are also described.  The application, referred to as WiscLEACH, is based on three analytical solutions to the advection-dispersion-reaction equation that describe transport in the vadose zone and groundwater.  The application was designed to be computationally efficient and can be used without experience in numerical modeling.  Predictions made with WiscLEACH indicate that maximum groundwater concentrations of trace elements leached from CCPs typically occur close to the groundwater table and near the center line of the pavement structure.  Peak groundwater concentrations decrease as the depth to groundwater increases, the thickness of the byproducts layer decreases, the seepage velocity in the vadose zone decreases, or the seepage velocity in groundwater increases.  Parametric studies have shown that the variables having the greatest influence on maximum concentrations in groundwater are depth to the groundwater table, thickness of the CCP layer, hydraulic conductivity of the least conductive layer in the vadose zone, hydraulic conductivity of the aquifer material,and the initial concentration in the CCP layer.

More information can be found in the following file:

WDNR-Alliant Final Draft Report

Summary

Reuse of Asphalt Shingles in Roadway Construction

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Approximately 11 million tons of reclaimed asphalt shingles (RAS) are disposed in landfills every year. Research has demonstrated that these materials can be recycled into a variety of products. A widespread, large-scale recycling and reuse application would utilize an otherwise wasted resource while clearing landfill space and creating new business opportunities. One potential reuse application is the utilization of RAS in the aggregate base (AB) and subbase (ASB) layers of roadway pavements and as working platforms for pavement construction over soft subgrades, and as embankment fills. RAS has the potential to act as an additive or substitute for the earth materials typically utilized in these applications. Like any recycling activity, the proper regulatory and permitting requirements for the reuse of RAS must be addressed. The purpose of this study was to determine the technical specifications of RAS, the effect of fly ash stabilization on RAS strength, and the practicality of the widespread implementation of RAS in roadway applications. RAS, fly ash stabilized RAS (S-RAS), RAS-aggregate mixtures, and RASsilt mixtures were evaluated for particle size characteristics, compaction characteristics, California Bearing Ratio (CBR), unconfined compressive strength, and resilient modulus. In summary, RAS is a granular material with particle size characteristics similar to that of well-graded sand, however, with very different particle shape and strength. RAS stiffness, in general, increases with increasing dry unit weight, and RAS dry unit weight increases with decreasing maximum particle size and increasing fines percentage; although the nature of RAS particles also play a role.

More information may be found in the following file:

RAS Final Report

summary

Ash Utilization In Low Volume Roads

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Utilization of byproducts is becoming a common method to improve the ride quality and structural capacity of roads.  Use of self-cementitious fly ash in stabilizing the existing roads (gravel roads or recycled paved roads) to form a stable base for hot mixed asphalt layer is of great interest as this reconstruction approach costs significantly less compared to traditional reconstruction where road surface materials are replaced with new aggregate base (estimated to be 1/3 of the traditional total reconstruction), more rapid and convenient. This report reviews the data collected at these two sites as well as other fly ash stabilization projects that the investigators monitored in Wisconsin to arrive at some general observations and conclusions.

More information can be found in the following file:

Revised Final Fly Ash Report Waseca+Chisago

Summary

Stabilization Of FGD Byproduct Using Fly Ash

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Fixated or stabilized flue gas desulfurization (FGD) scrubber material can be used as a stabilized base or subbase material in the same manner as lime-fly ash or cement-stabilized base materials.  Fixated FGD scrubber material may be used in an “as produced” condition, provided the material meets specifications, or the FGD scrubbermaterial can be modified with additional reagents such as Portland cement, lime, fly ash,etc. to improve characteristics. In addition to adding fixation reagents, an aggregate material (sometimes coal bottom ash) can be blended with the fixated FGD scrubbermaterial to improve material performance.  Properly designed fixated FGD scrubbermaterial has comparable strength development and durability characteristics to that of conventional stabilized base materials.

More information may be found in the following file:

FGD-study-report

Summary

Fly Ash Use In Reconstruction Of Bituminous Roads

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The purpose of this study was to develop a practical method to design local roadways using Stabilized Recycled Pavement Material (SRPM) or Stabilized Road Surface Gravel (SRSG) as the base layer and Class C fly ash as the stabilizing agent in the context of the “gravel equivalency” (GE) design methodology employed for local roads in Minnesota.  The project consisted of four major elements:  (i) laboratory testing ,  (ii) prototype pavement evaluation, (iii) field assessment of two existing roadways constructed with SRPM and SRSG, and (iv) assessment of potential impacts to ground water.

More information may be found in the following file:

TBE-Final-Summary-Report

Summary

Subbase Construction With Industrial Byproducts And Geosynthetic Reinforcement

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Investigation into alternative methods for providing a stable platform over soft sub-grades were evaluated using a 1.4-km section along a Wisconsin state highway that incorporated twelve test sections to evaluate nine different stabilization alternatives.  A variety of industrial by-products and geosynthetics were evaluated for stabilization.  The industrial by-products included foundry slag, foundry sand, bottom ash, and fly ash as subbase layer materials.  The geosynthetics included geocells, a non-woven geotextile, a woven geotextile, a drainage geocomposite, and a geogrid.  The same pavement structure was used for all test sections except for the subbase layer, which varied depending on the properties of the alternative material being used.  All test sections were designed to have approximately the same structural number as the conventional pavement structure used for the highway, which included a subbase of granular excavated rock.

More information may be found in the following file:

Byproducts Final Report

Summary

Strength Contribution and Equivalency of Subgrade Reinforcement Methods/Materials

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Two separate studies were conducted involving Sub-grade reinforcement methods/materials. Their primary focus was upon the strength of the sub-grade reinforcement materials and their respective equivalency criterion. Brief summaries are below:

Equivalency of Sub-grade Materials/Methods: The objective of this equivalency study was to develop a method for selecting the thickness of four alternative materials used in lieu of “breaker run” crushed rock as a working platform for highway construction on very soft sub-grade.  Breaker run is commonly used for working platforms, and thus was selected as the reference material.  Three industrial byproducts (bottom ash, foundry slag, and foundry sand)and a granular backfill were used as alternative materials.  A working platform of alternative material was considered equivalent to that with breaker run if the total deflection of the alternative material was equal to the total deflection of breaker run under the same construction loading.

Strength of Sub-grade Materials/Methods: The objective of this study was to develop a methodology for incorporating the structural contribution of a working platform into the AASHTO design method for pavements.  Two approaches have been proposed for flexible pavements.  In one approach, the structural contribution of the working platform is included by defining a structural number for the working platform as if it was a sub-base. In the other approach, the contribution of the working platform is included using a composite effective roadbed modulus.  The structural number approach is more direct and is preferred.  However, in some cases the structural number approach indicates that the working platform provides no structural contribution, whereas some improvement to the pavement system is expected when a strong working platform is placed on top of a soft sub-grade.

More information may be found in the following files:

Equivalency Final Report       Strength Contribution Final Report

Summary

In Situ Stabilization Of Gravel Roads With Fly Ash

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The focus of this project is to develop a new large-volume application for self-cementing coal combustion products, namely in situ stabilization of gravel roads using self-cementing CCPs.  Within the reduced scope of the project, the emphasis was placed on assessing the engineering properties of two recycled materials and a natural aggregate.  Laboratory experiments were conducted in which a road surface gravel(RSG), a recycled pavement material (RPM), a natural crushed aggregate (Class 5 base) were tested to determine the California bearing ratio (CBR), resilient modulus (Mr),and unconfined compressive strength (UCS).  The recycled materials were blended with two fly ash contents (10 and 15%) and three curing times (7, 28, and 56 d).  A Class Cfly ash with 0.7% loss on ignition was used.  Resilient modulus and unconfined compression strength tests were also conducted after 5 cycles of freezing and thawing to asses the impact of freeze-thaw cycling.

More information may be found in the following files:

05-CBRC-M16 Final Report

patent clearance

Summary

Environmental Benefits of Cold-in-Place Recycling

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The United States uses approximately 1.3 billion tons of aggregate every year, 58% of which is for road construction. Furthermore, 90% of aggregate used in road construction is virgin aggregate. With the increasing cost of virgin material sand the growing pressure to build more sustainably, the use of recycled materials in roads is becoming increasingly widespread. The triple bottom line of sustainability requires that a project is economically, socially, and environmentally beneficial relative to conventional methods. Cold-in-In-Place Recycling (CIR) is a method for highway resurfacing that has become more widely used in the past decade for its demonstrated benefits to the triple bottom line.

The project objective was to quantify the environmental life cycle benefits associated with using Cold-in-Place Recycling (CIR) for highway resurfacing instead of the conventional Mill and Overlay process. Equipment used and the quantity of materials used for both the CIR process and what would have been used in the Mill and Overlay process for the same project were collected for nine highway projects in Wisconsin. With this information, a life cycle assessment (LCA) tool, Pavement Life-cycle Assessment tool for Environment and Economic Effects (PaLATE) was used to analyze and compare each project’s data.

More information may be found in the following file:

Environmental Benefits of CIR TRB Report

 

Suitability Of Cement Kiln Dust For Reconstruction Of Bituminous Roads

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Most of the highways in the United States were built in 1950s and 1960s and have deteriorated significantly to date. More than 96% of the current highways and most surface streets are paved with asphalt. Asphaltic pavement that is removed during road reconstruction or rehabilitation is often landfilled with significant costs and environmental issues. Quarrying virgin aggregate for road reconstruction also results in environmental problems and energy consumption. There is an increased trend to recycle existing asphalt pavement in situ as base course for the new pavement surface. However, the load carrying capacity of such a base course is of concern due to the inclusion of asphalt and possibly fine-grained materials. Reuse of existing material in place would reduce material, transportation, and disposal costs and save energy. Much CKD is reintroduced to the Portland cement manufacturing process as kiln feed, but amounts are limited by alkalinity requirements for Portland cement and kiln operation issues. Too much CKD can clog parts of the system. Other options for reuse include soil stabilization, soil amendment for agriculture, and wastewater treatment. Cement kiln dust stabilization for rehabilitation of roads would provide another option to DOTs and municipalities depending on location and availability of suitable material.

The full thesis may be found in the following file:

Jeremy Baugh Master Thesis 2007

Leaching from Roadways Stabilized with Additive Coal Combustion Products (CCPs): Data Assessment and Synthesis

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Approximately 37% of the electrical power used in the United States is generated by coal-fired power plants. Air pollution control systems installed on coal-fired power plants collect solid byproducts of coal combustion, which are commonly referred to as coal combustion products (CCPs). Common CCPs include fly ash, bottom ash, boiler slag, and flue gas desulfurization (FGD) residuals. Disposing CCPs in landfills or similar waste containment facilities is costly and land intensive, and many CCPs have useful engineering properties. Consequently, CCPs are often used beneficially in other products or applications, most notably as construction materials. Beneficial use of CCPs has many positive benefits in the context of sustainability including an annual reduction in greenhouse gas emissions by 11 million tons, fossil fuel consumption by 17 TJ, and water consumption by 121 GL, amounting to more than $11 billion (US) in total economic benefits.
Field water quality data collected from roadways where fly ash or bottom ash was used as embankment fill or as a stabilizing agent in the base or subgrade was assessed for any potential risk of ground water and surface water trace element contamination. Trace element concentrations (e.g. As, Cd, etc.) were obtained for seven roadways in Minnesota, Wisconsin, Indiana, and Georgia, spanning the applications of fly ash base and subgrade stabilization, fly ash fill, and bottom ash fill.

The full thesis may be found in the following file:

Brigitte Brown Master Thesis 2015

Life Cycle Benefits of Recycled Materials in Highway Construction

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The use of recycled materials in highway construction has the potential to achieve significant benefits affecting the triple-bottom line (environment, prosperity, and society). Although state departments of transportation (DOTs) have been in the forefront of introducing recycled materials infrastructure projects, it has been challenging to clearly convey the benefits in a quantitative and transparent manner using easily understood metrics. What is lacking is direct information on sustainability assessment characteristics, i.e. greenhouse gas emissions, energy, water consumption, and waste generation.
To determine the benefits of using recycled materials for DOTs, the Recycled Materials Resource Center (RMRC) conducted life cycle assessments (LCA) and cost analyses using recycled material quantities provided by six-member state DOTs; Georgia (GDOT), Illinois(IDOT), Minnesota (MnDOT), Pennsylvania (PennDOT), Virginia (VDOT) and Wisconsin(WisDOT). PaLATE was used as the LCA analysis tool, after researching other publicly available tools to find an optimal analysis. Four environmental parameters (energy use, water consumption, carbon dioxide emissions, and hazardous waste generation) showed significant reductions when states used recycled industrial byproducts such as fly ash, and recycled roadway materials such as recycled concrete aggregate (RCA) and recycled asphalt pavement (RAP). The cost analysis indicated potential savings of up to 60 million dollars.

Life Cycle Benefits of Recycled Materials in Highway Construction TRB

 

 

Beneficial Reuse Of Foundry Sands In Controlled Low Strength Material

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The objective of this study was to characterize how properties of foundry sands affect the characteristics of flowable fill.  To meet this objective, tests were performed to evaluate flow, setting time, strength, and environmental degradation of flowable fills containing various foundry sands.  The results were used to develop general guidelines for successfully incorporating foundry sands into flowable fill.

The full thesis may be found in the following files:

Jefferey Dingrando Master Thesis 1999

Assessing the Life Cycle Benefits of Recycled Material In Road Construction

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There is interest in determining and validating the environmental and economic benefits of incorporating recycled materials into road construction using life cycle assessments (LCA) and life cycle cost analysis (LCCA) tools. However, the process of collecting the necessary data for LCAs and LCCAs from departments of transportations (DOTs) and road construction contractors is not well defined. This thesis provides a study of real-time data collection to compare with the results of pre-construction estimated LCA data. The goal of this comparison is to determine a data collection precedent for environmental analyses of future transportation projects. Additionally, two prominent LCA tools were used in conducting the assessment and the results were compared to validate the predicted impacts

The full thesis may be found in the following file:

Eleanor Bloom Master Thesis 2016

Strength And Stiffness Of Recycled Base Materials Blended With Fly Ash

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The objectives of this study were to assess the engineering properties of two recycled materials. Laboratory experiments were conducted in which a recycled pavement material (RPM) and a road surface gravel (RSG) were tested to determine the California bearing ratio (CBR), resilient modulus (Mr), and unconfined compressive strength (UCS). Results of these tests were compared to the properties of a conventional base material (Class 5 base). The recycled materials were blended with two fly ash contents (10 and 15%) and three curing times (7, 28, and 56 d). Resilient modulus and unconfined compression strength tests were also conducted after 5 cycles of freezing and thawing to asses the impact of freeze-thaw cycling.

The full thesis may be found in the following file:

Felipe Filizzola Camargo Master Thesis 2008

 

Beneficial Use of Dredged Materials in Great Lakes Commercial Ports for Transportation Projects

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This project focuses on beneficial use of DM as an alternative material for earthwork construction applications in the transportation sector (e.g., embankments, pavement base, etc.). The long term objective of the effort is to contribute to sustainable construction by facilitating use of DM instead of natural mined materials. The immediate objective, as described here and summarized in Figure 1.1, is to produce a set of guidelines that explicitly links together: 1) applications for the use of DM as construction materials in transportation-related earthwork projects, 2) required geotechnical properties of materials for specific construction applications, 3) geotechnical laboratory and field test methods available to determine these properties, 4) specifications (values) of these properties required for specific transportation-related projects, and 5) locations within the Great Lakes from which dredged materials having properties meeting these specifications may be sourced. The project is intended to build upon existing and more general frameworks for beneficial use of DM from the Great Lakes region (Great Lakes Commission, 2004) but within the specific context of using DM in the transportation construction sector. Emphasis is placed entirely on suitability in terms of physical characteristics. Suitability in terms of toxicity or environmental characteristics of the material is assumed.

The full thesis may be found in the following file:

Hua Yu Master Thesis 2014

Evaluating The Sustainability Of Construction With Recycled Materials

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A lack of data on quantified benefits that can be achieved through the
application of sustainability strategies acts as a barrier to the promotion of sustainable
movement. For this reason, two frameworks were developed to provide a quantitative
methodology for evaluating the benefits of sustainable construction and to rate the
relative benefits of construction projects compared to projects using conventional
construction concepts: a pairing method of comparative environmental and economic
life-cycle analyses for assessing construction; a rating system, the Building
Environmentally and Economically Sustainable Transportation Infrastructure-
HighwaysTM.
A pairing method was used to quantify the benefits of using recycled materials
in highway pavements by conducting life-cycle assessment and life-cycle cost analysis
on pavements consisting of conventional and recycled materials for a highway
construction project in Wisconsin. Results of the analysis indicate that using recycled
materials in the base and subbase layers of a pavement can result in reductions in
global warming potential, energy and water consumption, and hazardous waste
generation while also extending the service life of the pavement. In addition, using
recycled materials in the base and subbase layers can result in a life-cycle cost savings.

The full thesis may be found in the following file:

Jin Cheol Lee Dissertation 2010

The Beneficial Reuse Of Asphalt Shingles In Roadway Construction

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Approximately 11 million tons of reclaimed asphalt shingles (RAS) are disposed in landfills every year. Research has demonstrated that these materials can be recycled into a variety of products. A widespread, large-scale recycling and reuse application would utilize an otherwise wasted resource while clearing landfill space and creating new business opportunities. One potential reuse application is the utilization of RAS in the aggregate base (AB) and subbase (ASB) layers of roadway pavements and as working platforms for pavement construction over soft subgrades, and as embankment fills. RAS has the potential to act as an additive or substitute for the earth materials typically utilized in these applications. Like any recycling activity, the proper regulatory and permitting requirements for the reuse of RAS must be addressed. The purpose of this study was to determine the technical specifications of RAS, the effect of fly ash stabilization on RAS strength, and the practicality of the widespread implementation of RAS in roadway applications. RAS, fly ash stabilized RAS (S-RAS), RAS-aggregate mixtures, and RAS silt mixtures were evaluated for particle size characteristics, compaction characteristics, California Bearing Ratio (CBR), unconfined compressive strength, and resilient modulus. In summary, RAS is a granular material with particle size characteristics similar to that of well-graded sand, however, with very different particle shape and strength. RAS stiffness, in general, increases with increasing dry unit weight, and RAS dry unit weight increases with decreasing maximum particle size and increasing fines percentage; although the nature of RAS particles also play a role. The localized penetrative resistance, or CBR, of RAS is small.

The full thesis may be found in the following file:

Justin Warner Master Thesis 2007

Leaching From Soil Stabilized With Fly Ash: Behavior And Mechanisms

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In situ stabilizing soil with fly ash has become a practical and economical solution for construction on soft ground. However, leaching of trace elements from stabilized soil can be a concern. Understanding the pH-dependent leaching behavior and mechanisms controlling release of elements from soil-fly ash mixture is important for assessing the environmental impacts associated with using fly ash in soil stabilization. In this study, pH-dependent leaching tests were conducted to investigate the leaching behavior of soilfly ash mixtures used in roadway construction. The soils included organic clay, silt, clay, and sand. The fly ashes included Class C and off-specification high-carbon fly ashes. Four leaching patterns as a function of pH were observed: (i) leaching of Ca, Cd, Mg, and Sr follows a cationic pattern; (ii) leaching of Al, Fe, Cr, Cu, and Zn follows an amphoteric pattern; (iii) leaching of As and Se follows an oxyanionic pattern for some mixtures and anomalous leaching patterns for other mixtures; and (iv) leaching of Ba presents amphoteric-like pattern but less pH-dependent. Modeling results from MINTEQA2 indicated that release of the elements, except As and Se are solubility-controlled. For a given element, the solubility-controlling solids were found to be very consistent. Oxide and hydroxide minerals control leaching of Al, Fe, Cr, and Zn, whereas carbonate minerals control leaching of Mg and Cd. Leaching of Cu is controlled by oxide and/or carbonate minerals. Both carbonate and sulfate minerals are controlling solids for Ca, Ba, and Sr depending on pH of the leachate. The difference and inconsistency between the release behavior for As and Se and the other elements are probably due to different controlling mechanisms, such as sorption, or solid-solution formation.

The full thesis may be found in the following file:

Kanokwan Komonweeraket Dissertation 2010

Large Scale Model Experiments Of Recycled Base Course Materials Stabilized With Cement And Cement Kiln Dust

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The objectives of this study were to determine the resilient modulus of two recycled roadway materials: recycled pavement material (RPM) and road surface gravel (RSG) with and without cement and cement kiln dust (CKD) stabilization. The resilient modulus was determined by conducting Large Scale Model Experiments (LSME) designed to replicate field conditions, and compared with the resilient modulus determined from the laboratory test method described by NCHRP 1-28A. Results of wet-dry and freeze-thaw durability tests were used to select a portland cement content of 4% by weight and a CKD content of 10% by weight to chemically stabilize RPM and RSG. The stiffness at curing times of 7 and 28 days was evaluated, and the summary resilient modulus (SMR) corresponding to a bulk stress of 208 kPa was used to calculate AASHTO base layer coefficients for use in pavement layer thickness design. A conventional base course material specified as a Class 5 material gradation employed in Minnesota, and similar to AASHTO grading C, was used as a reference material. This study has shown that the addition of cement or CKD can significantly improve the stiffness of RPM and RSG, having the potential to allow greater use of recycled roadway materials in the reconstruction of roads, minimizing construction costs and environmental impacts. However, the low durability of materials mixed with CKD should be investigated further, because the expansion may be damaging to pavement structures.

The full thesis may be found in the following file:

Brian Kootstra Master Thesis 2011

 

Effect of Freeze and Thaw Cycling on Soils Stabilized using Fly Ash

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The objective of this research was to study how the resilient modulus and unconfined compressive strength of soils stabilized with fly ash change after freeze-thaw cycling.  To reach this objective, resilient modulus and unconfined compression tests were conducted on a range of fly ash stabilized materials after freeze-thaw cycling (0, 1, 3, 5, 10, and 12 cycles).  The stabilized materials tested included fine-grained soil, coarse-grained soil, and recycled pavement material.  Five different flyashes were used [Columbia and Riverside 7 (classified as Class C); Dewey, King and Riverside 8 (classified as off-specification)] at different percentages (10%, 12%,14% and 20%) and at three different water contents (7% wet of optimum, optimum,and at field water content).  Tests were also conducted on soil alone (0% fly ash)without freeze-thaw cycling to define the reference condition.

The full thesis may be found in the following files:

Maria Rosa Master Abstract 2007, Maria Rosa Master Thesis 2007

Leaching Of Trace Elements From Roadway Materials Stabilized With Fly Ash

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This study evaluated the leaching of trace elements from roadway materials physically stabilized with fly ash from coal combustion. Five field sites with stabilized materials and three sites with control materials used as base course or subgrade were constructed with pan lysimeters to collect leachate discharging from the bottom of the roadway layers. Pore volumes of flow from the layers was calculated from the volume of leachate collected, pH and Eh of the leachate was measured, and samples were collected for chemical analysis. Laboratory column leach tests (CLTs) and water leach tests (WLTs) were also conducted on specimens of some fly ash and base course/subgrade materials collected in the field. The type, concentration, and pattern of elemental leaching from field and laboratory specimens were determined, and concentrations were compared to those from control materials and relevant groundwater maximum contaminant levels (MCLs). The laboratory tests were compared for their utility in predicting field leaching behavior. The elements As, Cd, Cr, Mo, Ni, Pb, Se, and V exceeded MCLs and were elevated relative to control concentrations, with B, Mo, and V concentrations the most elevated from the controls, and exceeding the MCL for the longest time. Both CLTs and WLTs were similar in their utility for estimating peak field concentrations, especially when peak field concentrations were >500 μg/L.

The full thesis may be found in the following file:

Jonathan O’Donnell Master Thesis 2009

Evaluation of Recycled Materials as Backfill for Geosynthetically Reinforced Mechanically Stabilized Earth (MSE) Walls

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Recycled asphalt pavement (RAP) also satisfies general criteria for use in MSE backfill applications (e.g., grain size distribution, shear strength), but displays significant potential for deviatoric creep and thermal sensitivity due to its asphalt content. These issues require more attention for use of RAP in long-term applications. Similarly, foundry sand/slag, bottom ash, andiron/steel slag have suitable frictional and drainage properties. All of these materials, when compacted, display adequate friction angle required for MSE reinforced backfill. However,secondary issues such as compatibility with geosynthetic reinforcement, drainage, creep potential,and interface frictional behavior require more consideration.
The overall goal of this research is to facilitate use of RAP and RCA in reinforced backfills for MSE retaining wall construction. This thesis consists of five Chapters. In Chapter 1, the engineering properties of different types of recycled materials for potential use as backfill material are summarized from the literature. The design procedures for MSE walls, selection of backfill and geosynthetics, and current specifications are also summarized in Chapter 1. Chapter 2 summarizes issues related to responses of different types of recycled materials, as well as failure modes of MSE walls. The materials selected to conduct this research (including different types of geosynthetics and RAP and RCA samples) and testing procedures are described in Chapter 3. The experimental testing program includes index property tests, interface direct shear tests, pull-out tests and triaxial compression tests. Chapter 4 describes the test results and interpretation of the results. Chapter 5 summarizes the conclusions and recommendations from this research

The full thesis may be found in the following file:

Paulo Florio Master Thesis 2016

The Effects Of Climatic Conditions And Brick Content On Recycled Asphalt Pavement And Recycled Concrete Aggregate As Unbound Road Base

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This study evaluates the use of recycled concrete aggregate (RCA) and recycled asphalt pavement (RAP) as an unbound road base. This investigation looked at the climatic behavior (i.e., temperature effects, wet/dry cycling) of RAP and RCA and the effects of brick content on the resilient modulus and plastic strain (as an index) of RCA. The two chapters of this thesis individually discuss each one of these studies. The recycled materials used in this study came from a large geographical area covering eight U.S. states including California, Colorado, Michigan, Minnesota, New Jersey, Ohio, Texas and Wisconsin. Basalt and a quartz/granite/limestone blend meeting Minnesota Department of Transportation’s Class 5 gradation standard were used as control materials.

The full thesis may be found in the following file:

Ryan Shedivy Master Thesis 2012

Evaluation Of Metals Leaching From Gray Iron Foundry And Coal Combustion Byproducts

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This report is summarizes the results of two separate studies on the leaching ofmetals from industrial byproducts.  The first section of the report describes acomparative study on the leaching of metals from field and laboratory tests on industrialbyproducts used as highway construction materials.  The second section describes astudy on the leaching of metals from high-carbon fly ashes used to stabilize organicsoils.

The full thesis may be found in the following file:

Jacob Sauer Master Thesis 2006

Geotechnical Evaluation of Recycled Asphalt Shingles as Structural Fill

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To evaluate the effect of seasonal temperature on engineering properties of RAS mixtures, a thermo-mechanical system and the related testing procedures were developed. Systematic tests to evaluate engineering properties including hydraulic conductivity, one-dimensional compression, triaxial compression and deviatoric creep tests were conducted at constant and varying temperatures (between 5 oC and 35 oC). Results show that at room temperature, RAS mixtures are favorable lightweight materials with sufficient shear strength and drainage capacity for use in structural fills. Up to 50% RAS in granular materials and between 10 to 20% fly ash content in the stabilized RAS reduced the compressibility to meet the settlement criteria for roadway design. The secondary compression index increased as a power function with stress level. As the temperature increases the shear strength decreased due to reduction in viscosity of the asphalt binder in RAS particles. However the shear strength of the mixture with RAS content up to 50% remained higher than 30o . The hydraulic conductivity increased with ii increasing temperature due to reduction of viscosity of permeating water. The compressibility of the compacted RAS mixtures exponentially increased with temperature. Since the viscosity of RAS particles is reduced with temperature, if the embankment containing RAS mixture is constructed during warm season of the year the majority of the compression occurs during construction and the RAS embankment settlement during the rest of the year will be negligible. RAS mixtures were also susceptible to creep rupture under the applied deviatoric stress. When designing side slopes of the embankments containing RAS, the applied stress should be reduced to 80% of the maximum deviatoric stress to ensure no creep rupture will occur. Design graphs and analytical models were developed to predict shear strength and compressibility of RAS mixtures at constant and varying temperatures under the stress levels typical to highway embankments. The results of this research contribute to testing and design procedures associated with the use of recycled materials in geotechnical applications and help provide more sustainable roadway infrastructure.

The full thesis may be found in the following file:

Ali Soleimanbeigi Dissertation 2012

Stabilization Of Organic Soils Using Fly Ash

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Chemical stabilization of soft soils involves blending a binder (e.g., cement, lime,or fly ash or combinations thereof) with the soil in sufficient quantities to increase thestrength and stiffness to acceptable levels.  Fly ash, a by product of coal combustionthat is produced in vast quantities, is a binder of significant interest because many flyashes are available at low cost.  Past research has shown that many fly ashes areeffective for stabilizing soft inorganic soils, but little is known about their effectivenessfor stabilizing soft organic soils.  The objectives of this study were (i) to determine iffly ashes can stabilize organic soils and, if so, (ii) to quantify the improvement in theunconfined compressive strength and resilient modulus of the organic soil asadmixed with fly ash and (iii) to investigate potentially important factors affecting thestabilization process such as fly ash and soil characteristics, fly ash percentage in themixture, and water content.

The full thesis may be found in the following file:

Erdem Onur Tastan Master Thesis 2005

Hydraulic Properties of Recycled Pavement Aggregates and Effect of Soil Suction on Resilient Modulus for Pavement Design

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The successful incorporation of recycled aggregates in pavement design is important for achieving a higher level of sustainability in our transportation network. However, recycled aggregates are non-soil materials and have different unsaturated hydraulic and resilient modulus characteristics. This study investigated the unsaturated hydraulic properties and impact of soil suction on resilient modulus for compacted recycled aggregates used as unbound base course, including recycled asphalt pavement (RAP), recycled concrete aggregate (RCA), and recycled pavement material (RPM). Hydraulic properties and relationships including the soil-water characteristic curve (SWCC) and saturated and unsaturated hydraulic conductivity (Ks and K), were characterized using a hanging column test coupled with a large-scale testing cell. Regression of the hydraulic parameters from SWCC and K data for each type of recycled materials was completed. The effect of water repellency on hydraulic properties was evaluated. Development of testing equipment and procedures that incorporate the effect of soil suction during resilient modulus measurement is presented. A mathematical model to predict resilient modulus based on bulk stress, octahedrons shear stress, and soil suction is proposed. In addition, empirical relationships for predicting summary resilient modulus (SRM) via soil suction and SRM at optimum compaction for recycled aggregates are presented. Measured SRM and SWCCs for different types of recycled aggregate were used to evaluate flexible pavement performance according to the approach outlined in the Mechanistic-Empirical Pavement Design Guide (M-EPDG). The impact of environmental effects (including freeze-thaw cycles and changes in temperature) on the resilient modulus of recycled aggregates and subsequent pavement performance are evaluated and presented in this dissertation.

The full thesis may be found in the following file:

Kongrat Nokkaew Final Dissertation

Scaling and Equivalency of Bench-Scale Tests to Field Scale Conditions

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The objectives of this study were to determine the resilient modulus for recycled materials using Large-Scale Model Experiments (LSME) to replicate field conditions.  Tests were conducted on two recycled materials; recycled asphaltpavement (RAP) and recycled concrete aggregate (RCA), as well as on one blended material consisting of 50% RCA and 50% conventional base material (Class 5).  The results of LSME testing were compared to the resilient modulus determined using laboratory methods in accordance with NCHRP 1-28a and field scale methods using falling weight deflectometer (FWD).  The scalability of the laboratory results to field conditions was addressed by adjusting the resilient modulus to reflect a comparable stress-state and strain level.  The plastic deformation of materials tested in theLSME was also assessed.  A conventional base course meeting the gradation standard of a Minnesota Department of Transportation Class 5 aggregate was used as a reference material in this study.

The full thesis may be found in the following file:

G. Scheartl Master Thesis 2010

Recycled Materials as Backfill for Mechanically Stabilized Earth (MSE) Walls

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Granular materials are often the product of construction operations, industrial operations, or dredging operations in rivers, ports, and harbors. Traditional sources of reinforced granular backfill in Mechanically Stabilized Earth (MSE) wall construction (e.g., from crushed rock quarries and gravel pits) can be costly and environmentally not desirable. The use of recycled materials sourced from construction, industrial, or dredging operations could be a potentially more economical and environmentally beneficial source of backfill material than traditional sources. The overall goal of this project was to facilitate use of RAP and RCA in reinforced backfills for MSE retaining wall construction.

In this study mechanical and hydraulic properties of RCA and RAP for use in Mechanically Stabilized Earth (MSE) walls were evaluated. Results show that compacted RAP and RCA provide competitive pull-out resistance for woven geotextiles and uniaxial geogrids compared to compacted natural granular materials. Construction of a structural fill containing RAP is recommended to be undertaken during summer to reduce the creep strain and creep rupture potential and improve performance of the fill.

Chemical Characterization of Leachate Produced from RCA

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The proposed NPDES regulations in the State of Washington, requiring a pH below 8.5 at the point of discharge from recycled concrete aggregate (RCA), may have the unintended consequence of prohibiting the use of recycled concrete materials in commonly accepted concrete recycling applications; e.g., as unbound base course or fill material or aggregate in ready-mix concrete. A more appropriate method to determine compliance with pH regulations would be to determine a “point of compliance” and enforce pH regulations at that point. However, selection of an appropriate point of compliance is hindered by disagreement in previous studies on the pH of leachate as well as its acid neutralizing capacity (alkalinity). Most laboratory studies and many field studies suggest that the leachate pH should be very high (e.g., >9) for extended periods of time; however, the NAICS data presented in Figure 1 and results of our own field studies (Chen et al., 2012; Chen et al., 2013) suggest that leachate pH values above 8.5 are actually infrequent.   Here we propose to couple laboratory leaching studies, utilizing representative saturation and geochemical conditions, with results from a forensic examination of an RCA base course located at the MnROAD test facility to determine mechanisms that may limit the production of high pH of leachate.

For more information:

RMRC Proposal – RCA Leachate pH

State DOT Life Cycle Benefits of Recycled Material in Road Construction

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RMRC and various governmental agencies have developed fact sheets on various recycled materials and industrial byproducts for their use in highway construction applications. However, these fact sheets often lack direct information on sustainability assessment characteristics, i.e., greenhouse emissions, energy and water consumption, and life-cycle cost benefits. Although state transportation departments have been at the forefront of introducing recycled materials, they have not been able to clearly convey the benefits in a quantitative and transparent manner using easily understood metrics.

The first objective of this study is to develop/update fact sheets on various recycled materials and industrial byproducts that are being used in highway construction. New information generated in recent years relative to their engineering properties and environmental impact questions will be added as well as relevant life cycle assessment data. The second objective of this study is to develop a tool by which the state system-wide material use quantities can be used to calculate the life cycle benefits associated with the incorporation of recycled materials and industrial byproducts to highway pavement construction.

For more information:

Preliminary report for GeoChicago 2016 Conference: GeoChi Statewide

TRB Report: Life Cycle Benefits of Recycled Materials in Highway Construction TRB

Project Summary: Summary

 

Update of WiscLEACH Roadway Environmental Assessment Software

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Update of WiscLEACH Roadway Environmental Assessment Software

This project, in partnership with Jackson State University, updates on the development of a software program.  WiscLEACH, a web-based computing tool, is used to evaluate groundwater impacts from beneficial use of industrial byproducts in roadway stabilization and embankment.structural fill applications.

Recycled Base Course Materials Stabilized with Cement and Cement Kiln Dust

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Recycled Base Course Materials Stabilized with Cement and Cement Kiln Dust

The objectives of this study was to determine the resilient modulus of two recycled roadway materials: recycled pavement material and road surface gravel with and without cement and cement kiln dust stabilization. In order to replicate field conditions,  Large Scale Model Experiments were conducted.

Evaluation of Recycled Asphalt Shingles as Structural Fill

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Evaluation of Recycled Asphalt Shingles as Structural Fill

In this research, possible reuse of discarded asphalt shingles as structural fill was investigated. The engineering properties that were evaluated include: compaction characteristics, hydraulic conductivity, compressability shear strength, and coefficient of lateral earth pressure at rest.

Synthesis of Use of Crumb Rubber in Hot Mix Asphalt

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Synthesis of Use of Crumb Rubber in Hot Mix Asphalt

Ground tire rubber (GTR) is a unique recycled material and it is not clear what the optimum method for incorporating GTR in the asphalt is. This project focused on developing optimum methods of processing and blending GTR, reacting time between GTR and asphalt binders while blending, and the designing of GTR modified binders to yield superior performance.